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Tyler Claerbout
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Positive Productive Client Communication
By:Bryan OrrTyler Claerbout  In this insightful podcast episode, the host delves into the crucial aspects of positive and productive client communication, drawing from his extensive experience in the residential air conditioning industry. He emphasizes the importance of setting the right tone, bringing energy, building trust, and adapting to different customer personalities when interacting with […]
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Static Pressure, Manometers, and Magnehelics
By:Bryan Orr When you start talking airflow, it can get pretty in-depth pretty quickly. There is a big gap between what is useful for the average tech to apply every day and the whole story, so let's start with the simplest part to understand: static pressure. Static pressure is simply the force exerted in all […]
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Capacitor Testing and Replacement Procedure
By:Bryan Orr ❶ Understand What a Run Capacitor Does The run capacitor provides continuous phase-shifted current to the motor start winding, allowing the motor to run: With the design efficiency In the right direction With the appropriate torque With near “unity” power factor (power factor near 1.0) If the run capacitor is failed, the motor […]
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Why Compression Ratio Matters
By:Bryan Orr In HVAC/R, we are in the business of moving BTUs of heat, and we move BTUs via pounds of refrigerant. The more pounds we move, the more BTUs we move. In a single-stage HVAC/R compressor, the compression chamber maintains the same volume no matter the compression ratio. The thing that changes is the […]
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Weighing Refrigerant In and Out
By:Bryan Orr If you don't use a scale every time you add or remove refrigerant, I suggest you begin doing so immediately, if not sooner. Weighing in while charging is fairly obvious, and it's useful so you can keep track of what you are using and how much to charge a customer. When you have […]
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Scroll Compressor Pump Down, Megohm Test & Fusite Terminals
By:Bryan Orr This tip will be like an episode of Columbo; we will start with the what and who and then get to the why. Don't pump down a scroll into a vacuum. Don't run a scroll in a vacuum. Don't run a high voltage megohmmeter or Hi-pot test on a scroll (As a general […]
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Avoiding and Eliminating Callbacks
By:Bryan Orr Callbacks are horrible. They kill the trade from every possible angle. They destroy customer satisfaction and reduce technician morale by causing long hours, resulting in unprofitability for companies and less earning opportunity for everyone. Possibly worse of all, callbacks tell customers that you are no better than their cousin the maintenance man, or […]
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Laws of Energy and Matter
By:Bryan Orr It's always good to reaffirm some of the basics of energy, work, and matter, as these five rules are some of the most basic and important. The First Law of Thermodynamics States that energy cannot be created or destroyed. It can only change forms or be transferred from one object to another. If […]
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Sales: Techniques or Values?
By:Matthew Bruner“The very substance of our existing which has made us leaders in technique, stands as a barrier to any thinking which might be able to comprehend technique from beyond its own dynamism.” -George Grant The odd quote above takes some time to understand but has been rattling around in my brain for weeks now. […]
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When Subcooling is Meaningless – Short #161
 In this short podcast, Bryan talks about the times when subcooling is meaningless. It is important to understand subcooling fully before using it as a charging or diagnostic method, particularly in refrigeration systems. When we need to charge TXV systems in residential HVAC, many technicians rely on subcooling to set the charge. However, refrigeration […]
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Improving Humidity Control on the Cheap
By:Steve RogersThis tech tip was submitted by Steve Rogers, the current president of The Energy Conservatory (TEC). Steve has been on the podcast several times in the past and is a valued contributor to HVAC School. Thanks, Steve! As summer approaches, HVAC technicians all over the US are preparing for those difficult conversations with occupants […]
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Where Do I Measure Delta T?
By:Matthew BrunerOver time, I’ve seen people use just about every type of temperature-measuring device in just about every location imaginable. From drilling tiny holes into rooftop unit panels to sticking a K-type wire into a piece of flex duct (I don’t remember why), I’ve done it all.  Coming up through the trade, I’ve been TOLD […]
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What Changes Will You Soon See With the Shift to A2L Refrigerants?
By:Don GillisThis article was written by Don Gillis, the current Technical Training Manager at Chemours. Don was also involved in a popular symposium session about A2L refrigerants with Jason Obrzut and Dr. Chuck Allgood, which you can now watch for free on our YouTube channel HERE. Thanks, Don! We all know that the change to […]
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Plenum Takeoffs Best Practices
By:Matthew BrunerIn my second year in HVAC, I went out with a senior technician to install a supply duct for a bathroom in a house. While he ran the duct, I cut a hole in the plenum and attached the collar. He crawled back across the attic and very nicely told me that people don’t […]
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Residential AC Maintenance Process
By:Matthew BrunerI like processes. I especially like them in the HVAC profession because they give me confidence that I did the job correctly and save me time. When I’m following a process, I spend less time thinking about what I’m doing because my body and mind are trained by repetition. I particularly like processes that […]
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Replacing Residential HVAC Equipment With “Predictable Results”
By:Adam MufichWhen replacing a furnace or air handler for a customer, there is nothing worse than starting up the equipment and having it sound like the latest SpaceX rocket taking off. You insert your static pressure probes into the duct, and your stomach drops as you read the numbers.  You realize the new high-end system […]
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Manual D Speedsheet Walkthrough
By:Matthew BrunerBryan recently released a podcast on rules of thumb and how they can really get us in a pickle with sizing ductwork. With that in mind, I thought this might be a good time to do a walkthrough of Manual D from start to finish on a project I just finished up. My good […]
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Does Mass or Volume Move Heat?
By:Bryan Orr I once heard someone say, and have since repeated many times that BTU's ride on the back of Cubic Feet of Air or CFM. As I've learned more I've come to the conclusion that the weight or mass of the air passing over the evaporator coil is far more important to understand both […]
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The Strange Behavior of Moisture in Stuff
By:Bryan Orr Water is weird and water vapor is even weirder – before we dive down this rabbit hole lets define some terms To better understand the behavior of moisture in materials, we need to first define some essential terms and concepts: Relative Humidity (RH): The ratio of the amount of water vapor in the […]
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Impacts of Decreasing Evaporator Airflow
By:Bryan Orr Airflow, airflow, airflow… When we set up and commission comfort cooling and heating systems, we need to pay more attention to airflow before worrying about the fancy controls or the refrigerant circuit. One way to do that is by checking out Bill Spohn's Airflow 101 webinar on ESCO Group's learning network, which you […]
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Principles Of Troubleshooting: Seeing the Big Picture
By:Adam MufichIf you’ve been in this trade for any length of time, I’m sure you’ve run into situations that have left you scratching your head. If you’re lucky enough, you have the ability to call a senior tech, service manager, or company owner to bail you out of this situation. But have you ever run […]
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Smart Maintenance with SmartAC
By:Bert TestermanJosh Teekell
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Troubleshooting The Modern ECM
 Chris Mohalley returns to the podcast to talk about troubleshooting the modern ECM (or EC motor) and give diagnostic tips. ECMs are electronically commutated motors; they are mechanical motors with an electronic control module that dictates everything the motor does. As with all motors, ECMs have inputs and outputs. If the motor is not […]
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Condensate Drain Codes & Best Practices
By:Bryan Orr It should be stated and restated that codes and code enforcement vary from location to location within the US. The IMC (International Mechanical Code) is one of the most widely utilized and referenced. The 2015 version of the IMC section 307 is what I will be referring to in this article. Condensate Disposal  […]
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Homeowner’s Guide to Sizing an AC System (and who is responsible when you’re uncomfortable)
By:Bryan OrrThis tech tip was a collaborative effort between Matt Bruner, Adam Mufich, Ed Janowiak, and Genry Garcia. Thank you to everybody who gave their input! The next time you come across a homeowner who wants a bigger HVAC system, or you simply want to set expectations for a customer, share this tech tip with […]
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Diagnosing a Reversing Valve
By:Matthew BrunerIntroduction Replacing a reversing valve is either every technician’s dream or nightmare. The sheer amount of brazing involved in confined spaces will inspire either delight or nightmares about the upcoming valve replacement. Fortunately, these emotional highs and lows are uncommon because we don’t diagnose and replace bad reversing valves very often.  That itself poses […]
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Understanding “P” Traps in Refrigerant Lines
By:Don GillisThis article was written by Don Gillis with Chemours. Thanks, Don! There are 3 main reasons we use “P” or “U” traps: Assisting in oil return to the compressor Preventing oil accumulation in the evaporator  Preventing liquid refrigerant or oil from entering the compressor while operating or during the off cycle Assisting in oil […]
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Troubleshooting Inverter Boards
By:Roman BaughLet's talk about the magic that is inverters and how to test the boards that drive this technology. Inverters play an extremely important role in household appliances, industrial machinery, and the rising popularity of household HVAC systems. Inverters consist of a wide variety of electronic circuitry, and there are many situations in which they […]
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Air Barrier vs. Vapor Barrier vs. Insulation
By:Bryan Orr Think of it like this: It's a cold, wet, windy day. You can take an umbrella to protect you from the water alone, but that won't deal with the cold (temperature) or the wind (air convection). You can add in a light windbreaker, which will help keep the wind (convection) off. But if […]
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Gas Furnaces – What a Tech Needs to Know
By:Bryan OrrIt’s that time of year again—the furnace service calls are peaking. It’s a good idea to crack open Jason Obrzut’s book, Gas Heating: Furnaces, Boilers, Controls, Components, and listen to the many public podcasts and presentations by experts like Jim Bergmann. At HVAC School, we’re fortunate to have had some of the industry’s greatest […]
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Dunning-Kruger in HVAC
By:Adam MufichA few years ago, a friend of mine, Clive Mitchell, aka Big Clive, explained the Dunning-Kruger concept while he was a guest on my YouTube-based podcast, “HVAC Overtime.” Clive is another content creator on YouTube specializing in technical videos where he reverse-engineers electronic devices. Clive has a very analytical mind; he sees patterns in […]
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A Great HVAC Training Solution
By:Bryan Orr DISCLAIMER: I have no financial interest in HVAC Simulator or Dirk’s company, Nauman Innovation Group LLC. He is not a sponsor; I just think he’s a great guy who cares a lot about the industry, and I’m excited to share his work with other people who want to improve training and education in […]
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Why Many Techs Confuse Overload, Short, & Ground Fault
By:Bryan Orr The point of this article is to give you a full understanding of the role fuses, overloads, and circuit breakers play in the protection of HVAC/R equipment. If you skim-read or jump to conclusions, you will be tempted to argue. Be patient; if you want to understand, you will need to read all […]
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Do Houses Need to Breathe? w/ Allison Bailes
 Dr. Allison Bailes from Energy Vanguard joins the podcast to answer the age-old question: do houses need to breathe? He also talks about his new book, A House Needs to Breathe… Or Does It? You can purchase that book directly through the Energy Vanguard site at https://energyvanguardstore.com/ or on Amazon. HVAC professionals can benefit from learning about building […]
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We need to Pay Better! – An Audio Manifesto
 Eric Kaiser and Ty Branaman return to the podcast to talk about why we need to pay technicians and field workers better in the HVAC industry and how small and medium businesses can help current employees. When the pay for entry-level HVAC positions can't compete with fast-food, retail, or warehousing jobs, we can't expect […]
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Don’t Forget the Suction Filter Drier
By:Bryan Orr Courtesy of Emerson It is important to have refrigerant free from debris and contaminants, and we control these issues on many different fronts. 1. Proper tubing handling prevents copper shavings, dirt, and water from entering while installing. 2. Flowing nitrogen while brazing prevents carbon build-up. 3. Deep vacuum of 500 microns or less […]
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Electrification Panel
By:Jim BergmannBill SpohnKimberly Llewellyn
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Furnace Air Temperature Rise
By:Bryan Orr Every gas furnace data plate/tag has a specification for the temperature rise through that furnace. It is shown in a range like 50-80° or 45-75°. Those first two numbers are the lowest recommended temperature rise; the highest allowed temperature rise through the furnace is usually a 30° difference. When possible, we want to get […]
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A Story We Know
By:Bryan Orr Marley was dead, to begin with. There is no doubt whatever about that. That's the way Charles Dickens begins his “A Christmas Carol,” one of the most well-known pieces of literature in the modern world. A short story that can be read aloud in a few hours has to start memorably, and this […]
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Gas Furnace Maintenance Procedure
By:Bryan OrrThis gas furnace maintenance procedure in this article was developed by Michael Housh. Michael is the owner of Housh Home Energy in Ohio. He regularly works on natural gas equipment and is an active contributor to the HVAC School Facebook group. Thanks, Michael! Gas-fired equipment has a different set of components than your typical […]
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The Diagnosis Game (and Why Van Sleeping Bothers Me)
By:Bryan Orr The Sleeper  The year was 2002, and I was 20 years old. I had a helper named Clay, and he was a really nice guy, probably 15 years my senior, already with streaks of grey in his hair with a way of making you feel at ease—so very at ease. OK, he was […]
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Electrical Myths – Single phase is Really 2-Phase – Short #157
 In this short podcast, Bryan busts the common electrical myth that single-phase 240v power is really two-phase power. When power goes into a structure that runs 240v appliances, we may understand that two 120v sine waves are 180 degrees out of phase with each other, but that isn’t 100% accurate. If we were to […]
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The “Approach” Method of Charging and Condenser Efficiency
By:Bryan Orr We have discussed many methods for checking a refrigerant charge without connecting gauges over the last few years. Recently, I've been thinking about the “approach” method of charging that many Lennox systems require. What is the Approach Method? The “approach” simply refers to the temperature difference between the liquid line leaving the condenser […]
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Retrofitting Existing R-404A/R-507A Systems
By:Don GillisThis article was written by Don Gillis with Chemours. Thanks, Don! With the American Innovation Act (The AIM Act) in place and the reduction of the supply of hydrofluorocarbons (HFCs) in effect, the need to retrofit systems with lower global warming potential (GWP) refrigerants will become commonplace in the very near future. So, what […]
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Is it too cold to set the charge?
By:Bryan Orr I've heard the phrase, “It's too cold to set the charge!” for as long as I've been in the trade. I've also heard some variations of, “We need to come back and set the charge,” or, “We need to come back to do XYZ [some other thing].” Granted, there are cases where you […]
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A REALLY Loud Compressor
By:Bryan Orr A while ago, I walked up on one of our managers who was talking to a junior tech diagnosing an intermittent controls issue on a pool heat pump. In the background, you could hear an EXTREMELY loud compressor. The junior tech had just been moving some wires around, and the next thing he […]
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Pool Heater Water Flow Issues
By:Bert Testerman As you may already know, we work on pool heaters at Kalos as a way of opening ourselves up to some extra business during the winter. We find that it's a worthwhile line of work, and it may be something that other residential HVAC companies may want to consider doing. This tech tip […]
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Giving Thanks for the Hard Stuff
By:Bryan Orr Trigger Warning: This article isn't specifically about air conditioning, and it includes a markedly Christian worldview. If you would prefer that I “stick with the A/C stuff, preacher boy,” then this is one you should skip—or not. 🙂  Also, it's my birthday this week, so give me a pass.  Today, families all across […]
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Infrared vs. Heated Diode Leak Detectors
By:Bryan Orr Every HVAC/R tech needs an electronic leak detector nowadays, and with low-GWP HFC and HFO refrigerants getting more and more commonplace, every HVAC/R tech needs a VERY sensitive electronic leak detector. (Yes, electronic leak detection does work.) We often see three types, but let's toss out the corona discharge leak detector right off […]
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Infrared Thermometers Can Cause Confusion
By:Bryan Orr There are three reasons why I don't like infrared thermometers for many HVAC tasks. #1 – The laser can be misleading The laser dot is just a point of reference, not an exact point where it is reading. Often the thermometer will read lower, higher, or over a MUCH wider area. Unless you […]
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Why Measuring Static First Isn’t Always Productive
By:Bryan Orr There is a big move in residential and light commercial HVAC toward measuring static pressure regularly during commissioning, service, and maintenance. Don't get me wrong… Measuring static pressure is VERY important. The challenge comes in when techs begin taking measurements without understanding where to take them, what they mean, or worse: they use […]
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Heat Pump Defrost Boards and W2
By:Bryan Orr If you are used to simple, straight-cool split systems, you know that the low voltage to the outdoor unit is usually VERY simple. In many cases, there's just a Y (contactor power) and a C (common) connected to the outdoor unit. When the condensing unit controls are strictly two-wire low voltage, there is […]
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Electrical Myth – Wire Length Code – Short #155
 In this short podcast, Bryan covers a common electrical myth about wire length and its relationship with the National Electrical Code. The NEC is concerned with safety—protecting buildings and people—but less so with making sure things work. Wire sizing is a common topic, and length is important because it can contribute to the voltage […]
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Combustion and Confined Spaces
By:Bryan Orr All fuel-burning appliances require oxygen to burn. They require sufficient oxygen to burn clean and safely, without soot and CO (carbon monoxide). I live and work in Florida, where most of our fuel-burning appliances are 80% efficient with open combustion. (You can learn more about the basics of combustion on a podcast with […]
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The MOST IMPORTANT Skill a Tech Can Have
By:Bryan Orr I knew a tech when I was just starting who was hands down, no questions asked, the best technician at the company I worked. EVERYONE, we are talking over 60 techs… we all knew it. His name was Mike Gilford. Being the little brown-nosing ladder climber I was, I made a complete study […]
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Heat Exchanger Crack Diagnosis
By:Bryan Orr There are two camps I've run into regarding cracked heat exchanger diagnosis. There are those who look for it everywhere and those who dismiss it and never look. I will start by saying that everything I write here is my own opinion and experience. Because this is such a hot-button topic, don't take […]
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Why CO2 Matters w/ Trevor Matthews
Trevor Matthews, the founder of Refrigeration Mentor, returns to the podcast to talk about why CO2 matters in commercial refrigeration and even HVAC applications. CO2 (R-744) has entered the residential HVAC sphere in some places around the world, though it hasn’t come to the North American markets yet. CO2 is one of the most eco-friendly […]
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Crankcase Heaters
By:Bryan Orr Belly band crankcase heater When I first started in the trade as an apprentice, we worked on many Trane heat pumps that used crankcase heaters. These crankcase heaters slid into the compressor sump on the big orange Tyler reciprocating compressors. They looked like the one in the picture below. It was very common […]
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What You Need to Know About Microchannel
By:Bryan Orr Microchannel is a coil type used in many evaporator and condenser coils. You can easily identify it by its flat tubes, and its fins look like waves between the tubes. The technology was developed for use in the automotive industry and is used for radiators and automotive A/C condenser coils. These coils are […]
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Heat Doesn’t Rise
By:Bryan Orr We've all heard some version of the phrase “heat rises,” but is that really true? First, we need to remember that heat is energy, not matter. Heat is a force, not a thing. So, while heat may result in changes to matter (stuff), it isn't matter itself. When we add heat to stuff, […]
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Pre-Cleaning Copper
By:Bryan Orr Sometimes, we can focus on the more complicated aspects of a system and parts installation—like evacuation and flowing nitrogen—and forget the simple and critical common-sense steps to keep contaminants out of the system. One of these is pre-cleaning the tubing and connection before cutting or unsweating. For example: If you are replacing a […]
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Condenser Coil Cleaning Step by Step
By:Bryan Orr The photo above is of a real condenser coil we cleaned. The outer fins looked OK, but dirt and lint were packed deep inside. We also had sky-high head pressure and condensing temperature; those are telltale signs of an impacted condenser. That situation illustrates that a coil can sometimes look OK at first […]
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4 Silly Mistakes of The New HVAC Tech
By:Bryan Orr We've all been new at one time or another. So, there is no need to get all judgy about some of the mistakes new techs make just because they are inexperienced. However… These are some very preventable mistakes that occur due to simple oversights and carelessness that need to happen 0% of the […]
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What is a Micron?
By:Bryan Orr To answer the question in the title, we use it as a measurement of pressure. REALLY, it is a measurement of distance. First, any scale CAN be used to measure vacuum (negative pressure) and positive pressure. The trick is knowing which is best suited for which and the size of the scale. Larger […]
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Piston vs. TXV Metering Devices
By:Bryan Orr The piston (fixed orifice) and TXV (thermostatic expansion valve) are the two most common metering devices in use today, though some modern systems utilize an electronically-controlled metering device called an EEV (electronic expansion valve). It should be noted that there are other types of fixed-orifice metering devices, like capillary tubes; however, their use […]
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Why is the Breaker Tripping?
By:Bryan Orr Breakers are designed to trip anytime the circuit draws a current above the rating for a period of time. The time the breaker takes to trip is a function of how high the circuit amperage is compared to the breaker rating. The higher the amperage above the rating, the faster the breaker will […]
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The Unexpected Result of Series Circuits
By:Bryan Orr When I teach electrical basics, we do this exercise where we sit down and connect a 10-watt bulb to a power supply and through a switch. It's a SUPER SIMPLE circuit—the kind you might have learned about in a high school science class. But then I grab another 10-watt bulb and tell them […]
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The Friction Rate Chart (and What it Means)
By:Bryan Orr A lot of proper duct design comes down to an understanding of available static pressure and friction rate. We've covered this topic several times on this site and the podcast, but I wanted to focus on this ACCA chart specifically (shown above). If you want a deep dive, I highly recommend listening to […]
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The Basic Residential Maintenance for a Heat Pump / Electric System
By:Bryan Orr I need to warn you… The following list is the actual process we use at the company I own for our typical “standard” residential maintenance. I'm sure you will find some things you do differently. Take it for what it is, and I'm happy to get any feedback you may have. Read the […]
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Moving Forward with A2L refrigerants
By:Don GillisThis article about A2L refrigerants was written by Don Gillis with Chemours. Thanks, Don! HVACR service technicians find themselves at the forefront of the refrigerant transition in AC and commercial refrigeration. As hydrofluorocarbon (HFC) refrigerants with high-global warming potential (GWP) are being phased down, mildly flammable A2L refrigerants have been identified as potential lower-GWP […]
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Better Temperature Measurements
By:Bryan Orr I am in the midst of testing the accuracy and repeatability of different types of airflow measurements for techs in search of the most practical methods for different applications. A commonly taught method for measuring airflow is the temperature rise method, where you use a heat source that produces a set number of […]
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Technician Head Trash
By:Bryan Orr It's Friday at 6 PM. The schedule is clear, as far as you can tell. Other guys have been getting cleared right and left, so you call in standby. Five minutes pass. Ten minutes pass. You check in again, and sure as &%$#, there it is! You get sent across town to another […]
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Switch Voltage
By:Bryan Orr On an energized, intact circuit, you will read voltage across an OPEN switch when testing with a voltmeter. However, you probably won't read significant voltage across a CLOSED switch. Both sides of a closed switch are electrically identical (or at least very close). Therefore, there should be no movement of electrons between the […]
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Receiver Basics
By:Bryan Orr Receivers, which we sometimes call “liquid receivers,” are components that store refrigerant. You'll see it on everything from small self-contained refrigeration units to very large commercial and industrial systems. Many new techs who are used to residential air conditioning confuse receivers with accumulators. It's an understandable error, as they both contain liquid refrigerant. […]
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Adiabatic Cooling, Blower Settings, and Why You Care
By:Bryan Orr Just so you don't get bored and quit reading, let's get straight to the point. When the blower runs for more than a few minutes after the system has cycled off in cool mode, the air may continue to be “cooler” (lower sensible temperature) coming out of the supply. However, the heat content […]
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Understanding Relays With the 90-340
By:Bryan OrrRelays can be used for many different control applications, including controlling fans, blowers, other relays, or contactors, valves, dampers, pumps, and much more. A 90-340 is a very common, versatile relay that many techs have on their truck. So, we will use it as an example. A relay is just a remotely controlled switch […]
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Finishing Trade School? Some Things you Need to Know
By:Bryan Orr So, I hear you're just finishing trade school. Well done. You chose to take an excellent path, and now your journey is just beginning. How this will go is really up to you, and that's a good thing! You aren't going to be forced in one direction or another; you get to choose. […]
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Start Flowing Nitrogen Sooner
By:Bryan Orr My technician (and brother-in-law), Bert, made a good point. (It's hard for me to admit it, but it's true.) When he needs to open the refrigerant circuit to make a repair, regardless of whether he is recovering or pumping down, he pulls out his nitrogen tank and his regulator. (We like the Western […]
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The Sneaky Effects of Radiant Heat Transfer
By:Bryan Orr If you've ever sat close to a bonfire on a really cold night, you may have noticed that your face starts to get really warm. The minute you put your hands up and shield your face from the light of the flame, your face cools off almost immediately. That happens because the flame […]
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Tips for Managing Millennials and Zoomers
By:Bryan Orr Many of the “old-timers” in our trade are baby boomers; they were likely born after World War II ended and before the mid-1960s. These people grew up in a different time than today’s millennials (Gen Y) and zoomers (Gen Z). As those old-timers continue to retire, our trade needs to start attracting, recruiting, […]
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How to Reduce Indoor Humidity
By:Bryan Orr Sometimes I beat around the bush too much in these tech tips, so let's get down to the nitty-gritty! (As Nacho Libre would say.) Humidity inside a home should be maintained between 30% and 60% relative humidity. I like to shoot for 50% in humid climates when possible (and by possible, I mean […]
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Unapologetically a Technician
By:Bryan Orr For years, I've worked with and around people who view work, problems, and goals differently than I do. I've often told my wife that I have an issue managing and leading administrators, salespeople, and other inside staff. Why? It's because I just don't communicate in a way they seem to like. It's been […]
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Sight Glass / Moisture Indicator
By:Bryan Orr Often in commercial HVAC and refrigeration, you'll come across a sight glass/moisture indicator on the liquid line. (Oil sight glasses also exist, but those are different from what I'm talking about today.) Sight Glass The sight glass portion is simple; it's just there to show if the liquid line has a full line […]
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Why and How to Adjust a TXV/TEV
By:Bryan Orr As we discussed in an earlier podcast, a TXV maintains a specified and constant superheat at the evaporator coil outlet. It does this through a balance of forces between the bulb pressure (opening force), equalizer pressure (closing force), and spring pressure (closing force). We can actually adjust the spring pressure on some valves. […]
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Properly Deburring (Reaming)
By:Bryan Orr Deburring copper tubing (often called reaming) is the practice of running a blade around the inside of tubing after you cut it to remove the burr edge from the inside. It's an important practice and should be performed whenever possible. Deburring reduces turbulence inside the lines, as burrs can cause turbulence. HOWEVER… YOU […]
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Something to Watch For When Replacing a Thermostat
By:Bryan Orr Sometimes, you may have to replace a fancy thermostat with a simple one. It may be because the customer got fed up with all the options, or maybe the basic stat is the only thing on your truck. No matter the reason, you need to make sure the new thermostat can do the […]
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Refrigerant Oil Basics
By:Bryan Orr First, here's a quick summary of the role of oil in the refrigerant circuit: The compressor requires oil for the lubrication of the moving parts in the compressor. We would keep 100% of the oil in the compressor if we could. However, that is generally unrealistic. So, we need to utilize oils and […]
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Diagnosing and Finding a Refrigerant Restriction
By:Bryan Orr Photo by Ulises Palacios Refrigerant circuit restrictions can be common things like a plugged filter drier or a restricted metering device. They can also be more difficult to diagnose and stem from exotic issues like a kinked liquid line, blocked evaporator feeder tube, or a compressor connected improperly with a discharge line full […]
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What is a GFI?
By:Bryan Orr First off, the correct acronym for a GFI (ground fault interrupter) is “GFCI” (ground fault circuit interrupter). The purpose is to act as a safety device to protect from electrical shock. GFCIs are important components of electrical safety. GFCIs can be built into outlets, circuit breakers, and even extension cords. We generally use […]
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Parallel Circuit Resistance 
By:Bryan OrrIn a series circuit (loads connected in a row end to end), it's easy to calculate total circuit resistance because you simply add up all the resistances to get the total. In a parallel circuit, the voltage is the same across all the loads; the amperage is simply added up, but the resistance is […]
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Control Voltage Overamp – The Less Usual Cause
By:Bryan Orr In many cases when a low-voltage or control circuit blows a fuse, it's because one of the circuits is shorted to ground or common. That may happen because of rubbed-out wires, shorted components or boards, etc. Routing wires sensibly and using proper grommets to avoid rubouts and shorts will help prevent those problems. […]
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Making a Flare – Quick Tips
By:Bryan Orr This article is not a full lesson on making a flare, but it will give you some best practices to make a flare that doesn't leak. First off, we need to clarify that very few unitary manufacturers use flares anymore. You will most often find flares on ductless and VRF/VRV systems and in […]
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Electronic Leak Detection
By:Bryan Orr Electronic leak detection is a critical part of any HVAC technician's common practice. Unfortunately, it is also one of the most common sources of misdiagnosis. Here are my tips to make your leak detection more successful: Use Your Senses First and Your Detector Second  Before starting to use your detector, STOP! Look for […]
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Pull The Condenser Top
By:Bryan Orr The photo above is from a video one of my techs took of proper condenser cleaning. I must say, he did a GREAT job of cleaning the coil, and he was very careful with the top. However, I STILL would have liked to see him pull the condenser top completely during a full […]
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How to Use an Adjustable (Crescent) Wrench, Pipe Wrench and Tongue & Groove (Channel Locks) Wrenches
By:Bryan Orr My grandfather is a really interesting guy. He grew up working in the Pennsylvania coal mines starting at the age of 7 or 8. Then, he worked as a well driller, was a plumber, went to HVAC school, did some gas work, worked a while as an electrician, became a welder, was a […]
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What’s So Wrong With “Beer Can Cold”?
By:Bryan Orr First off, if you've never heard the term “beer can cold,” you are either not in the trade, or you have been living a pretty sheltered existence. I started as a tech apprentice when I was 17 years old, and on my first day in the truck, my trainer grabbed the suction line […]
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Condensation – It Isn’t Where Hot Meets Cold
By:Bryan Orr Photo by Stephen Rardon I hear it all the time. Someone will talk about undesired condensation on an air handler cabinet, on a supply air duct, in a ventilation duct, or on a vent like the one above. In reply, someone will inevitably say, “Condensation occurs where hot meets cold.” Early on in […]
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Negative Superheat? Time to Check Your Tools
By:Bryan Orr I was fresh out of school, working as an apprentice at my first real HVAC job, and I was listening in on a shop conversation between a few techs. They were talking about finding so many overcharged systems. One of the techs turns to me and says, “I had a unit yesterday that […]
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Does Refrigerant Get Old or Wear Out?
By:Bryan Orr Over the years, I have heard technicians say that refrigerant can wear out or “lose its blend” by sitting in a tank. Refrigerant does not wear out or “lose its blend”… at least not like that. What can and does happen is called “fractionation.” Refrigerant blends are composed of a mix of refrigerants […]
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HVAC/R Brazing Indicators
By:Bryan Orr When brazing and soldering, we have a few things we need to accomplish to make a proper connection: We can't overheat the joint until it overheats the base metal or the flux where applicable. We must bring the entire joint above the melting temperature of the brazing alloy. Draw the alloy deep into […]
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8 Tips for New Techs (So You Don’t Get Fired)
By:Bryan Orr If you are new to the trade, I'd like to welcome you. Like many skilled trades, the HVAC/R trade has many opportunities and can help you make a good living. If you are young and new to the trade, we need you. We are grateful to have you. However, if you aren't thoughtful, […]
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Cooling Capacity Isn’t Always What it Seems
By:Bryan Orr We all learned how to read the tonnage off of a model number within a few weeks of beginning in the trade. What you may (or may not) have learned is that just because something has an 036 in the model number, that does NOT mean it actually produces 36,000 BTU/hr. It doesn't […]
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Common Concrete Anchor Fails
By:Bryan Orr No matter what trade you work in, you will need to use a concrete anchor at one time or another. Here are some mistakes I have seen (and made) that you will want to avoid: Not knowing your concrete Is it a concrete block hollow cell? Poured cell? Concrete slab? What is the […]
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Setting & Checking Charges in the Rain
By:Bryan Orr I live in Central Florida, and while it can get pretty hot in the summer, we also tend to get afternoon thunderstorms that come and go in a flash. I have been connecting gauges, checking charges, and even pulling vacuums in the rain (even under umbrellas or cardboard boxes) for most of my […]
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Some Belt Tensioning Thoughts
By:Bryan Orr We had a really great conversation on the HVAC School Facebook Group about some belt tension best practices. It turns out that even a lot of really smart and experienced techs are not aware of all the factors related to belt tensioning. Myth #1 is that amperage is used to set belt tension. […]
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Beer & Power Factor – Short #144
By:Bryan Orr  Bryan describes the tricky concept of power factor and why we should care about it. He also compares power factor to a beer mug to make the topic easier to understand. Power is often represented on a sine wave, which is a curvy line that marks the state of electrical energy at […]
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Replacing a Compressor – Step by Step
By:Bryan Orr  In this podcast, Bryan goes through the entire process of replacing a compressor step-by-step. This process is what the Kalos team uses to replace a failed compressor and make sure it doesn’t fail again. Before replacing a compressor, you must figure out how the compressor failed; grounded conditions often lead to acid, […]
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A Common Sense Look at Temperature Conversions
By:Bryan Orr Before we convert temperature scales, let's take a step back and think about what temperature is in the first place. Temperature is proportional to the average kinetic energy of the random microscopic motions of the constituent microscopic particles, such as electrons, atoms, and molecules. Translation: Temperature is the average “movement energy” of the […]
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4 Training Tips for your HVAC Company
By:Bryan OrrTraining is important for businesses of all industries, but it’s especially vital to the success of your HVAC business.  When new people join your team, you need to be able to teach them the basics of your team’s operations, such as how to report time and log their travel expenses. Then, they must get […]
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What You Know About Start Winding Inrush Current Might Be Wrong
By:Bryan Orr Take a look at the specs from this Copeland scroll compressor pulled from the Copeland Mobile App (which is an incredible app, by the way). These specs are for a single-phase compressor, so the amperages listed are based on an amperage reading from the wire connected to the common terminal. LRA is the […]
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TXV Bulb Placement
By:Bryan Orr When mounting a TXV bulb or checking bulb placement, there are a few important considerations (listed in order of importance): Mount the bulb on the suction line. Flapping in the breeze is no good. Mount it TIGHTLY with a proper metallic strap (usually copper, brass, or stainless steel)—not with zip ties or tape. Position […]
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What does “Saturated State” mean for Techs?
By:Bryan Orr As we often do in these tech tips, we will start with the common and more practical explanation of saturation and then move to the more technical and nerdy explanation later. When we say “at saturation” or “saturated” in the HVAC/R trade, we are generally referring to the refrigerant that is in the […]
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Motor Speed – The Basics
By:Bryan Orr How does a typical single phase motor know how fast to run? Typical induction motors are dependent of the electrical cycle rate of the entering power (measured in hertz) for their speed. Our power in the US makes one complete rotation from positive electrical peak to positive peak 60 times per second or […]
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What the Heck is a Friction Rate?
By:Eric Kaiser Friction rate is a value located on a ductulator. We use it during the design phase of a duct system to predict the operating static pressure of a duct system. The challenge with friction rate is that it is often misapplied by folks using a rule of thumb (ROT). In order to apply […]
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Bypass Dehumidification/Airflow HVAC Design
By:Kaleb SaleebyThere have been several past posts on our Facebook group page about a concept called bypass dehumidification. I think technicians could benefit from learning more about this topic.  Bypass dehumidification or airflow is an interesting method for utilizing mixed air temperatures to maximize a system’s dehumidification capabilities. It's also a means of supplying adequate […]
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Static Pressure – Why Measure It?
This article was written by Neil Comparetto. Neil is one of the smartest and most thoughtful techs I know online. Thanks, Neil. Why measure static pressure? Because it's fun. I enjoy drilling holes in things. I rarely leave a house without drilling a hole in something. I also believe it’s an essential step to commissioning […]
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Does An Oversized Furnace Consume More Fuel?
This article was written by Michael Housh and was inspired by a discussion that took place on the HVAC School Facebook group. If you are already a member of the group, you can look at the oversized furnace discussion yourself HERE. I'd like to give a special thanks to Michael and everyone who contributed to the conversation. […]
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Commercial Rack Refrigeration Component Identification
By:Bryan OrrBrett WetzelKevin Compass Brett Wetzel and Kevin Compass from the Advanced Refrigeration Podcast join us to discuss commercial rack refrigeration and identify components. In supermarket racks, we typically have anywhere from 2-5 compressors on a single rack (with multiple evaporators, metering devices, and sometimes even condensers). These compressors may come in several varieties (including screw and […]
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Which Valve Do I Open First?
Testo 557 vacuum gauge and Appion core removal tools shown I've had a change of heart. Back in the early 2000s, during the big construction boom, I did many system startups on residential units for a large company I worked for. When installers ran the line sets prior to startup, they weren't always very careful […]
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Top Residential A/C Maintenance Tips
Bert recently made a video about his top residential A/C maintenance service tips. He showed some pretty good practices in there, so we’re going to revisit them in this article. Maintenance procedures are vital to any HVAC business, especially those specializing in residential A/C. When we do maintenances, the customers see our faces, and when […]
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Commercial HVAC Estimating
By:Bryan Orr Matthew and Nick Wavra join the podcast to discuss everything that goes into job estimation in commercial HVAC. Nick has a lot of fieldwork and project management experience, and Matthew has marketing, software, and sales experience, which helps bring in and retain clients. Commercial estimation begins when a mechanical contractor asks for a […]
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Liquid Quality vs. Subcooling
By:Bryan Orr In this podcast episode, Bryan and Eric Mele talk about sight glasses, the significance of subcooling in refrigeration, and liquid quality. While we measure subcooling quite often in HVAC work, we rely on sight glasses and liquid line receivers far more often in refrigeration. You need a sight glass to determine the liquid […]
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Understand Dew Point and Absolute Moisture, The Right Side of the Psych Chart
Let's first state the obvious. Most techs are intimidated by psychrometric charts and Mollier diagrams. We JUST ARE. While there are some pretty complicated formulas that back up these diagrams, using them isn't that big of a deal once you understand the different elements and then focus on one at a time. BUT WHY DO YOU […]
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What Causes Dirty Sock Syndrome?
I'm not sure who first started calling evaporator coil odors “dirty sock syndrome,” but I really wish they hadn't. Nowadays, every tech out there can't help but categorize every odor from the system as “dirty sock syndrome,” and customers just LOVE to hear that they have a “syndrome” named after a dirty locker room smell. […]
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Conduction, Convection, and Radiation
We may not realize it, but heat transfer inside our homes keeps the HVAC industry afloat. Without air conditioning in the summer, our buildings would remain stuffy, miserable places. That’s because heat can come from the outdoors, indoor objects (such as cooking appliances), and our bodies. So, this article will cover the three main types […]
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Dealing with Imposter Syndrome – Short 134
By:Bryan Orr Bryan discusses impostor syndrome, what it is, and how it may actually be useful for us. When we feel that we’re frauds and that others wouldn’t like to be led by us if they knew how much we don’t know, we’re experiencing impostor syndrome. Contrary to what others might believe, impostor syndrome isn’t […]
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It’s a Wonderful Life (Compression Refrigeration Edition)
Every year. We watch it EVERY YEAR, and it still gets to me again and again. Call me a sucker, but especially living a blue-collar life working in the trades, It's a Wonderful Life describes the way many of us live. Even more so, it captures the way we can start to feel about our […]
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Floating Suction and Head Pressure
This article was inspired by a podcast episode featuring Jeremy Smith. Jeremy is a refrigeration mechanic and has contributed a lot of good material to HVAC School. You can listen to that podcast on floating suction and head HERE. Those of you who drive your own vans are probably all too familiar with the following […]
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Flame Sensing – The Basics
Proving flame is an important part of the gas firing sequence. Without proof of flame, you risk dumping unspent gas into the heat exchanger, resulting in an explosion. There are many ways to “prove flame,” but we are focusing on the flame sensing rod (flame rectification) method here. Here are the facts: Flame sensing rods, […]
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Superheat Talk – Short 133
By:Bryan Orr In this short podcast, Bryan goes over the basics of superheat and explains why it matters to us. Superheat is the temperature increase above a substance’s saturation temperature or boiling point. When a substance is superheated, that means it is 100% vapor; there is no liquid at all. We can look at our […]
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Our Best 3D Animated Videos
By:Bryan Orr Over the past year, we have been adding 3D animations to our YouTube channel. It can be difficult to film everything we do in the field, so we've found 3D animations to be a helpful tool to show how parts work and how to do certain tasks. So far, we've uploaded nine 3D […]
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Transform Impostor Syndrome Into Wisdom
By:Bryan Orr This article was inspired by a recent short podcast episode covering a common issue among leaders, creatives, and technicians who try new things. You can listen to that podcast HERE. Maybe you’ve had a time in your life where you felt like a pretender. You’re really not as knowledgeable as people think, and […]
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Residential A/C Install Mindset and Practices
By:Bryan OrrWhether you’re putting an A/C unit in a new home or doing a retrofit, installation jobs make up a pretty big chunk of residential HVAC work.  Installation can be hard work, and there’s a lot more to it than throwing a unit together and making sure it starts up. When you consider building design, […]
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Conquering the Fear of Failure in a New HVAC Job
By:Bryan Orr When you first start your HVAC career, it’s pretty common to be afraid of failing or doing substandard work. The job market is competitive, and many new techs may worry that they’ll be inadequate and easy to replace. So, the fear of failure is common and understandable. Embarking on an HVAC career journey […]
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Old Books
By:Bryan Orr I've always liked old books. Think about an old printing press somewhere in Chicago or Boston or Scranton, Pennsylvania. Imagine workers with their hands covered in ink up to their elbows, setting type while giant machines of iron, steel, and brass stamp out a book page by page. Then those pages go on […]
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Why is 240V called “Single-Phase”?
By:Bryan Orr Why is it called single-phase 240 when there are two opposing phases (or legs)? I wondered why we called two 120v opposing legs “single-phase 240” for years. Then someone pointed out to me that a typical “single-phase” pole transformer only has one power leg entering and two coming out. That freaked me out. […]
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What is the “Mid Point” of a Refrigerant Blend?
By:Bryan Orr As we have mentioned in several previous articles (such as this one HERE), many blended refrigerants have glide, which simply means they boil and condense over a range of temperatures instead of just one temperature. As an example, consider refrigerant R407c. It is a zeotropic blend, which means it has enough glide to […]
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Maintenance During Major Repairs
By:Bryan Orr  Every contractor is different. I get that. We don't all need to do everything the same way or include the same services with repairs, but there are some “best practices” that can save you a lot of heartache before, during, and after you make a big repair. Catch it During Diagnosis Let's say […]
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W1, W2, & E
By:Bryan OrrI got this question via email (edited slightly for length): Some things I've done because I've been taught to do them yet I don't know why I do them. One of those things is putting a jumper between w1/e and w2. Sometimes, in the case of a Goodman for example, I've been taught to […]
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That Rusty Coil/Galvanic Corrosion
By:Bryan Orr How many times have you looked at the bottom right-hand side of an evaporator coil and seen all sorts of rust, even on a fairly new coil? You may have noticed that many evaporator coils and even some condenser coils will start to corrode where the galvanized steel endplates touch the copper u-bends […]
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What Techs Need to Know About A2L Refrigerants
By:Bryan Orr This article is based on the recent HVAC School podcast episode on A2L refrigerants with Jason Obrzut. You can listen to that podcast HERE. Jason is a member of the AHRI Safe Refrigerant Transition Task Force and has co-authored Refrigeration and Air Conditioning Technology (the RACT manual). You can access AHRI’s A2L refrigerant […]
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A2L Refrigerant Facts w/ Jason Obrzut
By:Jason ObrzutBryan Orr Jason Obrzut comes on the podcast to discuss A2L refrigerant facts. Jason is a member of AHRI’s Safe Refrigerant Transition Task Force and author of the RACT manual. ASHRAE designates refrigerants into categories based on toxicity (A or B) and flammability (traditionally 1, 2, and 3). So, the new A2L designation indicates […]
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Flaring Copper: Best Practices
By:Kaleb SaleebyTechnicians have to make flare fittings in the field every day. Most of the time, the application is for mini-split/ductless installs. However, you may encounter certain situations where flared fittings are more practical than a braze joint. Regardless of the reason, flared connections are notorious in our trade for being popular leak areas. Either the […]
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An Effective IAQ Process w/ John Ellis
By:Bryan OrrJohn Ellis In today’s podcast, John Ellis joins Bryan to talk about indoor air quality (IAQ). He also explains the ideal process for providing IAQ solutions. John has a lot of experience working as a consultant for people who have respiratory issues, so he has valuable perspectives. The HVAC and IAQ fields intersect in […]
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What Makes an Autotransformer Different?
By:Bryan Orr The definition of a transformer is a device that changes the voltages in an alternating current circuit. You may have heard of an autotransformer or a buck-boost transformer, and these terms are usually used for the same type of device; they just highlight different aspects. A transformer does not need to be a […]
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Caring for Technician Mental Health
By:Bryan OrrKaleb SaleebyScott Krasman In today’s podcast, Scott Krasman from TZOA, Andrew Greaves, and Kaleb Saleeby join Bryan for a conversation about mental health in the trades. We have a greater awareness of mental health than we ever did before, and although some of us may make fun of the topic, it is something we […]
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Compressor Mass Flow – Some Thought Experiments
By:Bryan Orr In order to wrap my head around diagnostic issues, it helps me engage in thought experiments where I think of more extreme examples of an issue or situation or consider the ideal to find the “edges” of a concept. Once I find the extreme edges, I can begin to sort down to a […]
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Does a Motor Draw More or Less at lower Voltage?
By:Bryan OrrHave you ever noticed that a blower motor rated for 120V draws about twice the amperage of the same horsepower motor rated at 240V? That is because motors are rated in watts or horsepower, and according to Watt's law, Watts = Volts x Amps. To keep the wattage output the same at 120V, it […]
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How to Measure Total System Airflow w/ Steven
By:Bryan OrrSteve Rogers In today’s podcast, Steven Rogers joins Bryan to talk about measuring total system airflow. Fluid measurement is NOT restricted to liquids; a fluid is anything that flows, including liquids and gases. In HVAC, we deal with both of them, but airflow is strictly limited to the flow of gas. The airflow we […]
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Is It OK To Top Off With R410a?
By:Bryan Orr I am consistently surprised by how much false information still circulates out in the field, and one of the ones I hear often is the idea that you cannot or should not “top-off” or recharge R410a systems on top of an existing charge of R410a when the system is low. So, to be […]
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Dealing With Tough Bosses & Co-Workers in HVAC/R
If you work with negative people, let them be miserable by themselves. The best way to deal with them is to ignore them while you're working. Instead of focusing on shared complaining, try to focus on the common goal of getting work done. Moreover, you can avoid contributing to a negative environment by leaving work […]
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Total External Static Pressure (TESP): A Basic Review
By:Kaleb Saleeby Probably the most popular measurement method for indirect airflow readings is total external static pressure (TESP). A dual-port manometer or two Bluetooth single-port manometers are essential to the HVAC technician toolbag. Here’s a quick review of TESP, why it’s important, and how to make the measurements. TESP is a pressure reading of the […]
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The Pressures Look Good
By:Kaleb Saleeby Yeah? Well, how do you know? What should they be? What are the outdoor and return air temperatures? What SEER rating is the equipment?  These are the questions I ask every single time a technician says the phrase,  “But the pressures look good for [insert refrigerant of choice here].”  When they can’t answer […]
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Planning and Layout of HVAC Projects
By:Bryan OrrEric Mele In today’s podcast, Eric Mele and Bryan explain the planning, layout, and execution of HVAC projects. They mostly cover commercial ductwork but also touch on piping and some residential projects. Planning The first step is to review the construction plan WITH a site visit. It is best to see how a plan […]
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Wiring Diagram Tracing – Older RHEEM Condenser
Bryan explains how to read schematics/diagrams on HVAC equipment and walks through an example. He takes a Rheem air conditioner and compares the physical unit to its point-by-point diagram and ladder schematic. Point-to-point diagrams illustrate how each component is wired in a piece of equipment; these tend to keep the same orientation as the physical […]
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Proper Liquid Line Drier Location
By:Bryan Orr Diagram above by Carrier  It's really easy to put a liquid line drier in the proper location, but it's still more commonly installed in the WRONG location. Namely, people install it right at the condensing unit. (OK, it isn't that big of a deal, but I needed some dramatic emphasis.) Installing it at […]
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System Performance Checks
Some technicians cannot perform effective system performance checks because they don't know the ins and outs of their tools. These technicians fail to maximize their tools' potential by not knowing where to measure, how to measure, or what their tools can do. Static pressure measurements are vital for system performance checks because of static pressure's […]
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Motor Overheating
By:Bryan Orr An important rating on motors is the AMBIENT  temperature rating that the motor can operate at. This rating refers to the temperature of the air around the motor, not the temperature of the motor itself or even the temperature of the outdoor air—since the motor is often in a condenser air stream that […]
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Careful With Cleaners
By:Bryan Orr When I was a green tech, I was really big into showing up all the other techs by doing THE BEST cleaning I possibly could. One of my favorite things to do was to clean the condenser until it was SPOTLESS inside and out. The only issue was that I really liked using […]
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Don’t Squeeze a Radiant Barrier
You are probably all familiar with radiant barriers. Sometimes, it is thin foil draped under the roof deck. Other times, it's used on the inside of stud walls or over furring strips before the drywall goes up, and there is even plywood with a radiant barrier attached to one side that is used for roof […]
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Are YOU an Autodidact?
By:Bryan Orr You probably didn’t expect to find the word “autodidact” on an HVAC education site. You’d probably expect to see it in an SAT prep book or a list of words to say five times fast. What does that word have to do with HVAC? Well, autodidacts are some of the best techs in […]
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Push-Pull Recovery – Short 119
By:Bryan Orr  In this short podcast episode, Bryan discusses push-pull recovery, how it works, and what we need to know about it. Push-pull recovery is a somewhat counterintuitive method of recovering liquid rapidly. We simply do that by pulling refrigerant out of the system and pushing it into the tank. However, when we pack refrigerant […]
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Why Selecting Equipment is Important (and Hard)
By:Bryan Orr I get questions all the time about performing “load calculations” and “rules of thumb” or how to do it properly. This article isn't about load calculation, but the only good answer is to find a quality ACCA-approved Manual J software and get used to using it. You may have heard from others in […]
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Indoor Air Quality Map & Compass w/ TZOA
By:Bryan OrrBen Reed In this podcast episode, Ben Reed from TZOA, a disruptive air technology brand, joins us to discuss the indoor air quality map and compass. We spend a majority of our lives indoors, so TZOA tries to improve IAQ in homes to keep us healthier. HVAC manages airborne chemicals, so indoor air quality […]
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Compressor Overheating Diagnosis & Prevention
By:Bryan OrrEric Mele In this podcast episode, Bryan and Eric Mele discuss the diagnosis and prevention of compressor overheating in HVAC and refrigeration. The main causes of compressor overheating are inadequate cooling back to the compressor, low charge, restrictions, and sometimes even poor suction line insulation. We want to keep the suction temperature low while […]
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ECM Types and Applications
By:Bryan OrrChris Mohalley In this podcast episode, Bryan and Chris Mohalley of Regal Beloit discuss the different types of ECM. They also cover applications where you can expect to find ECMs. In the HVAC industry, we typically use three types of motors: constant-torque, constant-airflow, and constant-speed. Every ECM works on electronic commutation, so constant-torque motors […]
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Zonal Pressure Diagnostics—The Backtalk Series (Part 3)
By:Genry GarciaThis article was submitted by Genry Garcia of Comfort Dynamics, Inc. It is the final part of his series on zonal pressure diagnostics. Thanks, Genry! Updated 3/4/2022 Picking up where we left off in part 2 of the series, we discussed how a pressure reading from an attached zone indicates only the ratio of […]
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Mean Radiant Temperature: What It Is and Why We Should Care
By:Kaleb SaleebyOur industry puts a lot of emphasis on the “AC” (air conditioning) part of HVAC. We specialize in maintaining and servicing a wide variety of simple to complex air distribution systems. But we’re really in the business of comfort—human comfort and health, to be precise. So, just how much does the human body rely […]
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What I’ve Learned From Teaching in a Trade School
By:Kaleb SaleebyI have been teaching at my local trade school as an HVAC instructor for the past year. It’s been a much different experience than training a technician on the job. Some of the students are already working in the field, and others have never been in an attic or crawl space. But regardless of […]
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An Evaporator Coil With No Fins?
By:Bryan Orr Let's use a bit of imagination for a minute. Imagine you have two totally identical 3-ton systems. One of them is completely normal, and the other has no fins at all on the evaporator coil. They both have the same charge, airflow, and compressor capacity. What will be different in terms of readings […]
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Ductless Line Sets and Corrosion
By:Bryan OrrThis article includes significant contributions from Neil Comparetto and Brian Chadwick, both of whom are HVAC technicians in Virginia. Brian is also the owner of Chadwick Air, and Neil is a co-owner of Comparetto Comfort Solutions and a longtime contributor to HVAC School. Thanks, guys! DISCLAIMER: A lot of the information in this article […]
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Averaging Thermistors and How They Work
By:Bryan Orr There was a question in the Facebook group a few days ago about averaging sensors. There are two common configurations/methods used for averaging. The first is simply a setting in a thermostat or control where it reads separate sensors, and then the thermostat itself averages out the readings using its software. For example, […]
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RH, DB, and WB
By:Bryan Orr I recently received a message asking for a discussion of relative humidity (RH), wet-bulb (WB), and dry-bulb (DB). Time and time again, I hear techs say that condensation occurs when “hot meets cold,” which may be true in some cases. However, that is only a shorthand way to describe it and doesn't really […]
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Historic Homes: Handle with Care
By:Bryan OrrThis article was written by Sam Myers with Retrotec. Thanks, Sam! If you’ve ever lived in a historic home, you’ve likely noticed that the level of comfort can change throughout different parts of the house. It can also typically change throughout different times of the year, depending on your climate. That is primarily due […]
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How EC Motors Work
By:Bryan OrrChris Mohalley In this podcast episode, Bryan and Chris Mohalley from Regal Beloit discuss EC motors. They also describe ECM applications and how those motors work. EC motors (ECMs or “ECM motors”) are electronically commutated motors. These motors are generally three-phase AC motors operated by a drive; that drive is a combination of an […]
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Atmospheric Pressure – Short 114
By:Bryan Orr In this short podcast episode, Bryan explains what atmospheric pressure really is, pressure units and conversions, and why those are matter. Atmospheric pressure is the weight of the air around us pushing down on us. We normally see that value expressed as 14.7 PSI (or 0 PSIG). Before we dive too deep into […]
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Swaging and Flaring Tips w/ AC Service Tech
By:Bryan OrrCraig Migliaccio In this episode, Bryan and Craig Migliaccio (AC Service Tech) talk about some best practices you can use while swaging and flaring copper. There are a few different ways you can flare copper. Craig likes using a round deburring tool before flaring the copper. After the burr has been cleanly removed, Craig […]
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Other Uses For Nitrogen – Short 113
By:Craig MigliaccioBryan Orr In this episode, Bryan and Craig Migliaccio (AC Service Tech) discuss all the ways that nitrogen can make your job easier. Nitrogen is an inert gas that we can use for purging refrigerant lines and completing scale-free brazing jobs. As techs, we should have at least one inert gas in our trucks […]
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Zonal Pressure Diagnostics—The Backtalk Series (Pt. 2)
This article was submitted by Genry Garcia of Comfort Dynamics, Inc. It is the second part of his series on zonal pressure diagnostics. Thanks, Genry! In Part 1 of this series, we outlined the basic understanding of ZPD—what it means and what it does. Most importantly, we showed how an effort to simplify a fairly […]
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Why (and When) Do We Need Defrost?
By:Jeremy SmithWhy Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or just parts of […]
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Zonal Pressure Diagnostics—The Backtalk Series (Pt. 1)
By:Genry GarciaThis article was submitted by Genry Garcia of Comfort Dynamics, Inc. It is the first part of his series on zonal pressure diagnostics. Thanks, Genry! Zonal pressure diagnostics have been around for a while. Here is a brief description of ZPD from the website redcalc.com:  Formerly known as the “Blasnik methods” in a nod […]
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Sweeping with Nitrogen
By:Bryan Orr Two days prior to this article being published, I sent one out about the popular fallacy that nitrogen “absorbs” moisture. That tech tip went out at 7 PM eastern time like usual, and I was sitting on the couch watching something on the Food Network (as usual). At 7:10 PM, I get a […]
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Learning from the Past vs. Allowing it to Control You
By:Bryan Orr In our line of work, it's all too easy to let your bad experiences inform your present and future experiences. That is especially true if you have a high emotional range. Having “emotional range” is a polite way of saying that you're a bit up and down (maybe even neurotic). We don’t believe […]
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Fan On or Fan Auto
By:Neil Comparetto Full disclosure: as a technician, I was guilty of setting the fan to “on” at the thermostat for many years. I never really thought of any of the negative impacts that could happen. I wanted to circulate the air and keep air moving through the high-efficiency air filter that most of our houses had. […]
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Tips for Cleaning an Air Conditioning Common Drain
Ethan from Kalos shows some of his best tips for cleaning a common drain and preventing drain related callbacks.  
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Gas Furnace Overview w/ AC Service Tech
Craig with AC service tech reviews a high efficiency gas furnace with sequence of operation and some important facts to know.  
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Motor Overload and Safeties – Kalos Meeting
We review hvac motor overload, reasons it happens, how to prevent it and what to do about it as well as low pressure and high pressure switches and furnace safties.
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A Common Electrical Mistake
It is common for techs to mix up compressor common with capacitor common or transformer common. Be uncommon and don't make these common errors.
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5 Traits of Bad HVAC Leaders
In this confessional we look at ways I've failed as a leaders and what good leaders should avoiding in an HVAC business.
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How to Braze Air Conditioning Copper
Attention Service Technicians and Installers! In this video Bryan explains How to Braze Air Conditioning Copper.
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How to Leak Test an AC With Nitrogen Pressure
In another one of our animated how to videos Bryan explains How to Leak Test an AC With Nitrogen Pressure.  
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How a Heat Pump Reversing Valve Works
By:Bryan OrrIf you don’t have a gas furnace or fireplace in your home, your unit’s reversing valve is probably your best friend during the winter months.  As their name suggests, reversing valves reverse the refrigerant flow to send the hot, compressed vapor to the indoor coil instead of the outdoor coil. The system releases heat […]
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Calculate Recovery Tank Fill the Easy Way
By:Bryan OrrRecovering refrigerant sounds like an easy task at first, especially with digital recovery machines and large hoses at our disposal. Unfortunately, we all know that filling the tanks is more complicated than it seems.  If you want to recover refrigerant and store it in a tank safely, you’re going to have to do some […]
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What is Isentropic Compression?
By:Bryan OrrThis article deals heavily with entropy. Entropy is not a simple topic, so we highly recommend checking out HVAC School’s Entropy in Refrigeration and Air Conditioning for some background information. Describing isentropic compression is a daunting endeavor. We all recognize the term compression, and I’m sure most of us can deduce that isentropic has […]
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Mini-Splits for New HVAC Techs
By:Ryan FindleyBryan OrrThis article was written by Ryan Findley. Thanks, Ryan! This article will be geared toward HVAC techs who are new to mini-splits. As the mini-split market continues to grow, technicians face more and more challenges with these systems. The most critical challenges would be insufficient training and the lack of proper tools to […]
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Refrigeration Without Refrigerant
By:Bryan OrrWe just wrote about rejecting heat to the atmosphere via radiant cooling. That’s one example of cooling without refrigerants, but there are quite a few others out there. In this article, we’ll look at some other cooling methods that don’t use refrigerants. Vortex tubes Vortex tubes swirl gas in a chamber, separating it into […]
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4 Silly Mistakes of The Green HVAC Tech
  We cover some common and very silly mistakes we can all make as well as ways to prevent them and what to do to succeed in hvac as a new tech.
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Adjusting Gas Pressure on a Standard and Gemini Furnace Valve
A quick video on two different gas valves: a Standard and Gemini Furnace Valve.  
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Service Valve Tips – Short 105
By:Bryan Orr In this short podcast episode, Bryan talks about some tips you can use when working with a multi-position service valve. A service valve will have a line connection, which connects the valve to your line set. You also have a gauge port that you can connect to, a valve stem, and a packing […]
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Refrigeration Scroll Compressors
By:Trevor MatthewsBryan Orr In this podcast episode, Bryan and Trevor Matthews from Emerson talk through scroll compressors in commercial refrigeration equipment. Scroll compressors are not a monolith; although they all function similarly, they have different fine details and manufacturing protocols by application. Low-temp, medium-temp, high-temp, and A/C scroll compressors each have unique designs, operating conditions, […]
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What is Net Refrigeration Effect (NRE)?
By:Bryan Orr Net refrigeration effect (NRE) is the quantity of heat that each pound of the refrigerant absorbs in the refrigerated space to produce useful cooling. That’s a pretty vague definition. We know that it’s an amount of heat in processes that take place within the evaporator. Still, the phrase “useful cooling” seems rather broad. […]
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How a Heat Pump Reversing Valve Works
A Quick overview of Reversing Valve on Heat Pump System.
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Don’t Confuse TD & Delta T
We cover what TD and delta T are in HVAC/R language as well as why they get confused and how to use the terms productively.
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How to Send Heat to Outer Space—What Ancients Knew That You Don’t
By:Bryan Orr You likely already know a bit about radiant heating from your education and work in the HVAC industry. Science textbooks like to use the sun and campfires as classic examples of radiant heat transfer. We also have plenty of heating devices with radiation right in the name, such as water radiator heaters and […]
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What is Compressor Volumetric Efficiency?
By:Bryan Orr Simply stated, a compressor’s volumetric efficiency (VE) is its ability to pump the most pounds of refrigerant over time. The compressor’s function is right in the name: it compresses vapor refrigerant. After compression, the gas moves to the condenser via the discharge line. From there, the refrigeration cycle continues. However, some of the […]
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False Alarms: The Legacy of Phosgene Gas
By:Bryan OrrWe’ve all been in the unenviable position of unsweating a compressor and getting blasted in the eyes with a waft of gas that smells like burning sulfur from the pits of Hades. As we stagger back, covering our noses and holding our breaths, memories of the phrase “phosphene gas” from trade school or World […]
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Entropy in Refrigeration and Air Conditioning
By:Bryan Orr In the trade, we talk a lot about changes in enthalpy, especially when we are looking at total heat exchange over an evaporator. Sometimes, you will bump into the word entropy, and I wanted to take a stab at making it more understandable. Many people understand entropy as the condition in which molecules […]
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Do You Replace the Contactor and Capacitor With a New Compressor
Replacing a compressor is expensive, time-consuming, and physically taxing. If we are replacing a compressor, I want us to be doggone sure we aren't going to be dealing with the same thing again, and this often includes a shiny new contactor and capacitor (on single-phase units). We received a comment recently that called out the […]
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Stuck Contactor Issue
Bryan shows a corroded Contactor that is stuck.
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Tips for Hiring & Getting Hired
How to find a good job? How to get into the trade? Struggling to find skilled people? Bryan answers all these questions and more in this video.
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How to Build a Sheet Metal Coil Case From Scratch
Eduard is back to show you How to Build a Sheet Metal Coil Case From Scratch.
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How to Recover Refrigerant Quickly and Properly
By:Bryan Orr The way we use and think of refrigerants is evolving quite rapidly. As we shift towards phasing out ozone-depleting refrigerants and considering alternatives, the future of refrigerants may seem a little uncertain to us. However, one thing is certain. Many HVAC units will continue to rely on the common HCFC, HFC, and HFO […]
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The What and Why of SEER2
By:Bryan Orr Many techs may not all know what SEER exactly means or how it’s calculated, but we know that it exists, is regulated by the government, and has something to do with efficiency. SEER is the standard efficiency rating of central air conditioning systems, and its values are determined from a controlled set of […]
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Heat Pumps in Cold Climates
By:Bryan Orr   In this episode, we are joined by three people who know a lot about heat pumps and cold weather. We also cover everything from the way technologies have changed, some of the pitfalls to keep away from, and why heat pumps work even in really cold climates nowadays. Chad Gillespie: Chad is […]
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Drain Cleaning – More To It Than We Think
By:Bryan OrrMike KlokusCorey Cruz Mike Klokus and Corey Cruz from Kalos come on the podcast to talk about drain cleaning. They discuss their tips and some best practices. Approximately 50% of the calls in the light commercial division have to do with drains, and drain cleaning is a common PM procedure. The procedure starts off […]
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Top 10 HVAC Tech Tips
By:Bryan OrrThis article is based on HVAC School’s special video for 100k subscribers. The episode features Eric Mele, Andrew Greaves, and Sam Behncke as special guests. To celebrate HVAC School’s 100,000 YouTube subscribers milestone, we've released a video on a topic that applies to all sorts of HVAC techs. Customers don’t like making callbacks, and […]
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What Air Filter is The Best?
In this meeting we look at how to choose the right air filter by considering size, depth, MERV, measured and system static pressure.
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Some Furnace Questions
I received an email from a podcast listener with some furnace-related questions. Based on the nature of the questions, I figured it would be better to ask an experienced furnace tech. Benoît Mongeau agreed to help by answering the questions.  My name is Matt and I am a newer tech (fully licensed this September, have […]
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Understand Heat Pumps
By:Bryan Orr My goal in this tech tip is to help those who struggle to understand heat pumps get their heads around them as quickly as possible and understand some of the things a tech needs to know about them. The basic idea of a heat pump is to use the compression refrigeration cycle to […]
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Testing Home Pressure Imbalance w/ Genry Garcia (Spanish)
In this video Home Performance Unicorn tech and owner Genry Garcia shows us how to check home pressures to find issues using a precise manometer and more.
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Removing a Blower Motor
By:Kaleb Saleeby I’ve seen a lot of guys recently who reach for the motor puller tool first thing when attempting to remove a blower motor from a wheel/fan blade. Motor puller tools are an awesome backup tool when needed, but using a motor puller tool shouldn’t be the go-to method of removing a motor. The […]
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The Case For Pulling The Blower Housing
By:Bryan Orr When I started in the trade in 1999, there were still many oilable blower motors in service. As part of the maintenance, we would remove the housing and oil the motor. We would also vacuum the motor and wipe it down. As oilable motors have become extinct, I see fewer and fewer techs […]
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Single-Pole Contactors & Crankcase Heaters
By:Bryan OrrKaleb Saleeby Kaleb, Joe, and Eric join us again to discuss some myths about single-pole contactors. We also cover some weird crankcase heater wiring configurations. When you have a single-pole contactor on a unit with no other resistance crankcase heater attached, the contactor energizes the compressor but is NOT a source of crankcase heat. […]
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Soft Skills Can Be Hard (Disciplines of Growth)
Being a successful HVAC tech takes many of the same disciplines it takes to grow in any career and in personal life. This meeting covers some big areas where discipline is critical. –Brayn
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Introduction to CoreSense
By:Trevor MatthewsBryan Orr Trevor Matthews from Emerson Canada joins us on the HVAC School podcast again to talk about CoreSense by Emerson. Each CoreSense module has the potential to protect compressors. The technology can detect issues like overheating, short cycling, locked rotor, missing phase, low oil, and more. In short, the goal is to notify […]
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Delivered Capacity Basics – Kalos Meeting
Jesse Claerbout, Kalos' Residential GM, reviews the importance of delivered capacity measurement. –Bryan
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Piston Design and Bypass
By:Bryan Orr I remember it like it was yesterday. It was my first day of work as a trainee at my first technician job, just a wet-behind-the-ears kid fresh out of trade school. It was a Monday morning, and the technicians and I were standing in the dusty warehouse surrounded by stacks and stacks of […]
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Does the Voltage or the Amperage Kill You?
By:Bryan Orr I hear the following phrase a lot: It's the amperage that kills you, not the voltage. While there is truth to the statement, it is sort of like saying, “It's the size of the vehicle, not the speed that kills you when it hits you.” OK, so that's a pretty bad example, but […]
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Duct Installation Best Practices
By:Bryan OrrKaleb SaleebyNeil Comparetto In this podcast episode, Neil Comparetto from Comparetto Comfort Solutions joins Bryan and Kaleb to discuss some duct installation best practices he has learned. You might be able to take away some of his duct installation tips and apply them in the field. Neil used to focus a lot on making […]
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Troubleshooting and Commissioning Q&A
By:Bryan OrrEric KaiserKaleb Saleeby In this podcast episode, Kaleb, Joe, Eric, and Bryan answer some troubleshooting and commissioning questions from Facebook. Whether we're talking about troubleshooting, commissioning, or any other HVAC/R task, the best training is on-the-job training. Meetings, educational videos, and quizzes also help to a lesser extent, but bypassing training altogether is a […]
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Dielectric Grease: What It Is and How To Use It
By:Kaleb Saleeby Dielectric grease is an often misused and misunderstood product that could easily benefit HVAC/R technicians in various ways. From food service to electrical connections, dielectric grease can help lubricate mechanical components and prevent corrosion on electrical connections. But we need to understand what it is in the first place before we can properly […]
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Connecting Transformers in Parallel
By:Bryan Orr I had an old-timer tell me that you can never connect two transformers together because they will “fight one another.” If you are anything like me (and heaven help you if you are), a cartoon in your head starts playing whenever someone says something like that. In this case, I imagine two transformers […]
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EPA 608 Core Prep – Part 1
Bryan Orr embarks on the EPA 608 Prep series, this is Part 1 that covers the core material of the testing –Bryan
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Checking Evaporators on Furnaces
By:Bryan Orr In Florida, there are not many gas furnaces—at least not as many as up north. Sometimes, we can look like real dummies compared to techs who work on them every day. One thing to know about 80% gas furnaces with cased evaporator coils is that you can often check the evaporator coil by […]
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What Should My Superheat Be?
By:Bryan Orr  The most common—and often most frustrating—questions that trainers and senior techs get asked sound something like this: “What should my ______ be?” or “My _____ is at ______. Does that sound right?” Usually, when the conversation is over, both the senior and junior techs walk away feeling frustrated because the junior tech just […]
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Diagnosing and Replacing a Run Capacitor
Bryan does an onsite demonstration of Diagnosing and Replacing a Run Capacitor. –Bryan
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Crankcase Heaters and Single-Pole Contactors
By:Bryan Orr We keep two-pole, 40-amp 24v coil contactors on all of our vans. They are versatile and reliable, and you can replace most residential A/C contactors with them. There are a few things to watch for, though, especially when you have a crankcase heater. Many brands power the crankcase heater constantly and shut it […]
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TD of Refrigeration Evaporators
By:Bryan Orr We have discussed DTD (design temperature difference) quite a bit for air conditioning applications, but what about refrigeration? Let's start by defining our terms again. Suction Saturation Temperature The saturation temperature is the temperature at which the refrigerant will be at a given pressure if it is currently changing state. This change of […]
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Shielded Control Cable & Communicating Controls
By:Bryan Orr When I first started in the trade, we used to run into shielded control wires on the Carrier Comfort Zone 1 zoning systems and also on a Carrier VVT system I used to maintain at a bank. I knew it has something to do with electrical “noise” and that communicating systems often called […]
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Cycle Rate Settings – A Quick Review
By:Bryan Orr Most controls and thermostats will have some sort of cycle rate per hour setting that kicks in to prevent over-cycling once the setpoint is reached. These cycle settings don't kick in until the system starts achieving setpoint, so don't worry if it will shut off if it's set to 70° in heat mode […]
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Fan Blade Shroud Depth
When a system has abnormally high head pressure (high condensing temperature over ambient) and compression ratio, one of the easiest things to look for is a dirty condenser coil. More often than not, that will be the cause. However… There is another category of issues that can cause high condensing temperature (high head pressure), but these […]
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What to Check Before Condemning the TXV
I just noticed this portion of the Carrier air handler sticker for the first time the other day. I'm like most techs; it's easy for us to ignore the great info posted right in front of us on the data tag. That's because so many of the notices contain info we are used to seeing. […]
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DUCTLESS Control and Humidity Hack with Cielo Breez
Check out DUCTLESS Control and Humidity Hack with Cielo Breeze. –Bryan
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Size and Orientation of Return Grilles and Supply Registers
Proper sizing and orientation of grilles, registers, and diffusers may seem like such a simple thing, but it's an area where confusion and mistakes are commonly made. First, let's define some terms. Return  A return draws air into a return duct system with negative pressure compared to the space, usually via a fixed “grille” (also […]
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Does Setpoint Lead to Freezing?
Does setting a thermostat too low cause an air conditioning system set in cool mode to freeze? The answer is no, at least not directly. However, low evaporator load (low return temperature or low airflow) and low outdoor ambient temperature can lead to evaporator coil freezing. Low indoor setpoint can lead to low return air […]
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Low Voltage Electrical Basics
By:Bryan OrrKaleb Saleeby Bryan and Kaleb cover the basics of low-voltage electrical applications. They focus on the practical stuff, not just the theory that confuses techs. Many techs have a hard time with low-voltage electrical concepts and components because it's not easy to visualize what happens; we only see wiring diagrams, not metaphors that help […]
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Human Comfort Basics – RSES NATE Prep
Some NATE prep basics on keeping people comfortable from the RSES NATE prep presentations available at RSES.org –Bryan
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Flex Ducts – Best Practices
Some techs and contractors swear that flex ducts are an evil invention and should never be used in ANY circumstance. I agree with what duct design expert Jack Rise said on the podcast when I asked him about flex ducts: “There's a lot of problems with flex duct, there really is, and it's a good product, […]
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5 Install Mistakes that Kill Systems
  Bryan streams an in-depth presentation on 5 Install Mistakes that Kill Systems. A must watch for everyone who wants to keep their HVAC systems Safe & Sound.     –Bryan
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Hot Pull Down and What it Means
If you work in refrigeration, you may have heard the term “hot pull down.” This phrase describes a condition where the load on the evaporator is above design due to the box temperature or the temperature of the product in the box being higher than it would normally be. My grandpa called me a few […]
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Refrigerant Charging Basics For Air Conditioning & Heat Pump Systems
Before I start on this one… At HVAC School, we focus on a wide range of topics. Many of them are very basic. My experience as a trainer for over 16 years has taught me that no matter what I assume others SHOULD know, it doesn't change the fact that they often do not. This […]
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Coil SHR, Ventilation, and Bypass Factor – Advanced Psychrometrics Part 2
This is the second article in a three-part series where we explore advanced psychrometrics. The source material for each of the articles in this series is ACCA Manual P Sections 3, 4, and 5. This article is based on information found in Section 4. If you followed the previous advanced psychrometrics article, you now know […]
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Refrigerants, Flammable & Toxic
There has never been a more complicated and confusing time surrounding refrigerants than what we are in right now. We are seeing flammable HC (hydrocarbon) refrigerants with increasing regularity, and EPA rules that just changed appear to be changing again. With all this tumultuous change, it's important to know what to look for in refrigerants […]
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C stands for “Common Mistake”
You have seen the C terminal on a dual run capacitor before. You have also seen the C terminal on a compressor. It stands to reason that they would both connect together, right? They don't connect, and they aren't even related, at least not in the way you think. In both cases, the C denotes […]
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Locating a Low Voltage Short in Residential A/C Systems
Newer technicians often get hung up and frustrated when searching for low voltage shorts. This is understandable due to the broad spectrum of possibilities for the location of the short. However, this doesn’t mean that the process needs to be complex. The time it takes to find a low voltage short may vary greatly depending […]
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5 Things to Consider When Maintaining a Commercial Package Unit
If you are primarily a residential technician working on equipment under 5 tons, there are many similarities between the systems you are used to and 5-20 ton rooftop units common to the light commercial market. There are MANY additional things to consider on larger equipment, and here are just a few. Wash Fresh Air Filters […]
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Refrigeration Pump-down Cycle
This article was written by Jeremy Smith CM, an experienced refrigeration tech and all-around great dude. Thanks, Jeremy. A very common means of control seen on refrigeration equipment is the pump down control. Why do we use this rather than just cycling the compressor off and on like a residential HVAC unit? Since most refrigeration equipment […]
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What Should My Subcooling Be?
  This is the article you read BEFORE you call and ask a senior tech what your subcool should be. It's also the one you send to a junior tech when they call and ask you: So, what is subcooling? (Or subcool, as many call it.) Subcooling is a measurement of temperature DECREASE of a […]
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Wiring and Setting of Humidistat/Dehumidistat in Humid Climates
If you live in a dry climate, a humidistat is pretty straightforward; it just turns a humidifier on and off. That's about as simple as it gets. If you are in a humid climate, some people have taken to wiring in humidistats as dehumidistats to help control humidity when they are away. The first thing […]
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Trap and Vent – A Drain Debacle
This picture is from a recent call I ran that clearly had an interesting past. It had a condensate pump to pump the water just a few feet up to a drain that went to a common drain. The “cleanout” after the trap is supposed to be a vent, not a cleanout, which means it […]
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Why A/C Systems Freeze
Let's start with the basics. Water freezes at 32° Fahrenheit (0° Celsius) at sea level and at atmospheric pressure. When any surface is below that temperature, and the air around it contains moisture, ice/frost will form. In some situations, ice is to be expected, such as in refrigeration evaporators and exposed portions of the refrigeration […]
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The Surefire Way to Get a Blower Wheel Off
I've always opposed the practice of grabbing a hub puller as the first method of removing a blower. This video by Brad Hicks with HVAC in SC on YouTube demonstrates the exact method I use to safely remove a blower wheel without damaging anything. Thanks, Brad! Transcript What's going on, guys? Here's another 60-second tech […]
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Advanced Combustion Analysis (HVAC) w/ Jim Bergmann
Jim Bergmann shows us HVAC Advanced Combustion for Furnaces and more using BluFlame from AccuTools. Learn how to avoid CO exposure from a real expert! –Bryan
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How to Flow Nitrogen While Brazing
Bert is back! He uses a setup he made for Jim Bergmann to show ya'll How to Flow Nitrogen While Brazing. –Bryan
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Wet Bulb and Enthalpy – The Left Side of the Chart
Both wet-bulb temperature and air enthalpy are extremely useful to understand when calculating actual system capacity and human comfort. Dry-bulb temperature is a reading of the average molecular velocity of dry air. However, it does not account for the actual heat content of the air or the evaporative cooling effect of the air. When air […]
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Oxidizers and What It Has to Do With COVID-19
Oxidation is the loss of electrons, reduction is the gain of electrons, and the reaction is what occurs between the two. When we talk about chemistry or chemical reactions, we are really talking about an electrical interaction between molecules seeking equilibrium. In other the words, the old “high voltage goes to low voltage” rule applies […]
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Refrigeration Gas Defrost
Let's take a deeper dive into the magic that is gas defrost. Most techs who are familiar with heat pumps understand the basics of a gas defrost. When we apply this strategy to a larger system where we're only reversing a small part of the system, we need to add some controls and valves to […]
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Liquid Line Solenoid Valves: Long Line Applications
Pump down solenoid valves are commonplace for any refrigeration technician. They are energized with the compressor still running, shutting off flow in the liquid line so that the refrigerant is pumped into the condenser and receiver. The compressor will then shut off once a low-pressure switch opens the circuit when the pressure falls below a […]
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Wide, Narrow, Wide Diagnosis
When you walk up to a piece of equipment, you want to follow a process to ensure that you accomplish five things: #1 – You diagnose the fault correctly. #2 – If possible, you find the “why” of the failure. #3 – Find any other problems or potential problems with the system that can cause […]
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The Ductless Dehumidification Conundrum
This tech tip was a COMMENT on a Facebook question about how ductless systems achieve some of their high-efficiency numbers at the expense of dehumidification. This was the question: Bryan Orr mentioned that multi-stage mini splits often do very little latent cooling (dehumidification) because on low speed the manufacturers all “let the evaporator float, which […]
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Trades and the Skills Gap – A Manifesto
This article is a year old, and I'm recycling it because it's on my mind today. I had a fun conversation with Richard Trethewey on the podcast that has me thinking along these lines today. The link is HERE if the player isn't showing up. I have a confession to make. I'm a bit of […]
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Checking the Charge on a Heat Pump in the Winter
When you ask many people nowadays how to check the charge on a heat pump during low outdoor temps, they will say that you need to “weigh in and weigh out” the charge. While this may be an effective method, it isn't always practical. Now, if you are making a refrigerant circuit repair, weighing out […]
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The Learning Mindset – Trial & Error
I'm far from a country boy, but I did grow up in a rural area with animals, playing in the woods, and cleaning out chicken coops. Like many of you, we would play most of the day outside without our parents knowing or worrying about where we were. Was that an “unsafe” way to grow […]
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Codes and Failed Inspections #LIVE
By:Bryan Orr In this live podcast from the Castbox app, we talk about codes and common causes for failed inspections. We talk about these topics both broadly and with some specifics. Many of the places where we fail to meet codes are on the electrical side. Electrical components have fire and electrical shock hazards, and […]
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Balanced Port TXV
  I walked into a supply house the other day and looked at a “universal” expansion valve on the shelf. The friendly guy behind the counter saw me and walked over. After saying hello, he said: “That's a great valve; it's even balanced port.” Now, I am a bit of a troublemaker. I should have […]
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Recovery Machine Speed Race 🏁NAVAC NRDD Digital vs. Appion G5 Twin
Bert and Jesus test NAVAC NRDD Digital vs. Appion G5 Twin in Recovery Machine Speed Race. Sponsored by NAVAC: https://navacglobal.com/ –Bryan
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A thermostat miswire and distracted diagnosis #BERTLIFE
BERT IS BACK #BERTLIFE – Bert finds a shut off breaker, some thermostat issues and gives a sermon on distracted diagnosis –Bryan
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Mixed Air Temperature w/ David Richardson
By:David RichardsonBryan Orr David Richardson with NCI, author of Duct Dynasty, joins us on the podcast to talk about mixed air temperature and more topics of interest. When you bring outside air into the home, you introduce positive pressure into the home. That way, you can offset air lost via mechanical ventilation or through cracks, improving […]
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It Has a Flat For a Reason
When tightening down a blower wheel or a fan blade on a motor shaft, ONLY tighten it on the flat of the shaft. If you have more than one screw but only one flat surface on the shaft, only tighten the one set screw. Also… Refrain from over-tightening set screws; they need to bite into […]
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Inductive Reactance in Real Life
Bryan explains how Inductive Reactance functions in Real Life. –Bryan
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The HVAC/R Diagnosis Pyramid of Skill
WARNING: THIS ARTICLE CONTAINS GENERALIZATIONS. IT DOES NOT APPLY TO EVERYONE, AND WE HAVE ALL PROBABLY BEEN ALL OF THESE AT ONE POINT OR ANOTHER. IF YOU FEEL PERSONALLY ATTACKED, I SUGGEST FINDING A SAFE SPACE AT A WEST COAST UNIVERSITY AND BORROWING A BINKY FROM A NEARBY TODDLER. ALSO, MY CAPS LOCK BUTTON IS […]
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Milivolt Systems w/ Modern Thermostats
Jesse Grandbois is a tech who reads the tech tips, and he wrote a few tips that he wanted to share on some gas furnace control basics. This tip is about how to use a fancy digital stat on a millivolt system. For those of you who don't know, a millivolt system uses a thermocouple/thermopile […]
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An Electric Heat Mistake
I started working as a tech when I was 17 years old, fresh out of trade school. My first winter out on my own, I went to a service call in an older part of Orlando, a part of town I had never worked in before. It was an especially cold winter that year, and […]
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How (and Why) to Flow Nitrogen While Brazing
When I started in the trade, the idea of flowing nitrogen while brazing was nothing more than the punchline of a joke. Like pulling a vacuum with a micron gauge or proper recovery, it was a wink and nod proposition rather than a real practice. I've had to unlearn many bad habits since those early […]
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Clocking a Gas Meter (It’s not that hard)
I've heard a lot made of clocking gas meters over the years, and honestly, in Florida, there isn't too much call for heat. There are even fewer furnaces. I was pleasantly surprised when I found out how easy it actually is. Here is how you do it, step by step: #1 – Make sure all […]
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Recovery Tank Capacity
  To start, I'm going to cut straight to the part that most of you want to know. This information is based on calculations I have done personally based on typical Mastercool DOT tanks, but feel free to come to your own conclusions based on your own calculations. I prefer to stay on the safe […]
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Don’t Forget the Panel
See the photo above? This is a unit we (my company) serviced for a commercial customer. It doesn't matter if we aligned the belt, dialed in the charge, cleaned the condenser (using THIS thorough process), and got the drain pan clean. We look like dummies because the panel fell off. Also, as you may notice, […]
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The Slow Death of the Honest Technician
I was sitting in a session at the HVAC Excellence educators conference (which was excellent, by the way), and my phone buzzed. So, like a typical punk kid, I looked down at it to see that my friend Josh had sent me a Facebook message asking if we served the east side of Orlando because […]
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Know the Limits of Subcooling
This article was written by RSES CM and excellent market refrigeration tech Jeremy Smith. Thanks, Jeremy! I frequently see techs online struggling with charging or troubleshooting refrigeration equipment and using subcooling as a diagnostic or charging method. Please don't do this unless you understand it fully. Many times, trying to charge a refrigeration system to […]
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Modulation Motors
Modulation motors are not often seen in residential equipment, but we see them a lot in commercial and industrial applications on many different types of equipment. I see them primarily on larger burners to control the fuel firing rate, but they also control water flow through heating coils, the water level on cooling towers, and […]
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Tech Question – Why Do ECM Motors Trip a GFCI?
This question was submitted on the site in response to the recent GFCI tip. It's a good question with several possible answers. What do you think? Hey Bryan, I have had a few instances where we are firing off a furnace in a new build with a temporary power pole outside with gfci outlets installed […]
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Don’t Install Your Micron Gauge at the Pump
Have you ever wondered why your old refrigerator never needs service or gauges installed and can run for 30 years that way, maybe only needing an occasional cleaning of the condenser? For crying out loud, utilities are buying these old energy hogs through some programs because they never seem to die. Why do they last […]
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Testing a Thermocouple
First, a thermocouple is not a flame rectifier like a modern flame sensor. A thermocouple actually generates a millivolt potential difference when it is heated by a flame—just to get that out of the way for any of you newer techs who are used to modern flame sensors. With higher efficiency gas-fired equipment being the […]
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Like a Bull in a China Shop – An Oversizing Story
This article was written by Genry Garcia of Comfort Dynamics, Inc. Thanks, Genry! This is a piece about oversized air conditioners. Though the symptoms and consequences of oversized heating equipment are similar to those of air conditioners, you’ll notice that the focus throughout the article will be on the cooling side—specifically from the perspective of […]
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Three-Phase Voltage Imbalance
When reading ANY article about electrical theory or application, keep in mind that it will only scratch the topic's surface. You can dedicate years of your life to understanding electrical theory and design the way many engineers do and still know just enough to be dangerous. In HVAC, we rarely need to have a DEEP […]
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What is a HSO (non-bleed) TXV/TEV?
There is a lot of misunderstanding about the HSO (hard shut-off) or “non-bleed” TXV (thermostat expansion valve) and what makes it shut off, why it exists, and how it “magically” opens. Once you understand the forces inside the valve, it is quite simple, obvious, and sadly devoid of any magic. The Three Forces  The TXV […]
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The 10 Commandments of the HVAC/R Technician
One trait I've seen with good technicians is that they take their jobs VERY seriously, but they learn not to take themselves too seriously. A few months ago, I had someone tell me online that I must think I'm the A/C “god” because I'm always telling everyone the “right” way to do things. This got […]
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The Dangers of Like-for-Like Tonnage
By:Alex MeaneyBryan Orr Alex Meaney from Wrightsoft joins us to talk about Manual J and S. He also discusses how load calculations and equipment selection apply to real-world situations where contractors are tempted to replace “like-for-like.” Load calculations have been a staple of new installations, but they are becoming important in retrofits as well. We […]
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Accumulator & Burnout Considerations
The suction line accumulator is designed to keep liquid refrigerant from entering the compressor while still allowing for oil return. The trouble is that if the oil return port/screen clogs, the accumulator can fill with oil and actually cause the compressor to fail. In addition to that, it can hold contaminated oil in a burnout. […]
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ECM, VFD, and Inverter – What’s the Difference?
Ever since Nikola Tesla invented the modern induction motor, we have been struggling with varying the speed of motors efficiently and reliably. The trouble in the HVAC industry is that there are several different types of technologies in play, and they can easily get confused. ECM (electronically commutated motor) In residential and light commercial HVAC, […]
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How to Make Ductless Flares That Won’t Leak
In this video we go step by step into how we make flares with a flaring tool for a mini-split ductless air conditioner including NAVAC flaring tools, deburring, torque wrenches and more.. –Bryan
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Refrigeration Case Controllers w/ Sporlan
By:Bryan Orr In this podcast episode, Henry Papa from Sporlan joins us in person to talk about refrigeration case controllers on systems with common compressors. We focus on the Sporlan S3C case controller, but some of the information applies to other case controllers. Case controllers control the conditions at each separate evaporator and are responsible […]
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The Good Old Heat Anticipator
As a technician, you most likely know some customers who still have an oldie thermostat (you know, those old mercury bulb things, like the round Honeywell CT87 and such). Keep in mind that those usually have an adjustable heat anticipator. If you’re newer in the field, you may not have seen or worked with those […]
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ECM Motors A-Z w/ Eric Kaiser
By:Bryan OrrEric Kaiser Eric Kaiser joins the podcast again, and this time, we are talking ECM motors. We discuss types, history, diagnosis, and failure prevention. An ECM motor has a permanent magnet rotor, which means that the magnetism never deactivates. The variable frequency-driven motor is typically an induction motor, and the rotor only becomes magnetized […]
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A Liquid Line Solenoid and What it Does
Depending on what segment of the business you are in and your location, you either work on pump down solenoid systems all the time, or YOU HAVE NO CLUE what they are. A liquid line solenoid is just a valve that opens and closes; it has a magnetic coil. Depending on whether the valve is […]
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Open and Closed Case
I know I'm gonna get some eye-rolling here, but it needs to be said. When we teach electricity to new techs, we use a lot of “water” metaphors. We talk about volts like PSI, amps like flow, and watts like GPM (speaking of GPM in HVAC, check out our article on hydronics HERE). Even the […]
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Refrigeration Compressor Teardown Class
Mike Nipper from Copeland teaches a Compressor Teardown Class at HVAC school / Kalos offices. presented by: https://www.emerson.com/en-us –Bryan
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How to Charge an AC
By:Bryan Orr Craig of AC Service Tech on YouTube joins Bryan on the podcast to explain how to charge an A/C unit. He also discusses his excellent new book. Before you start charging a unit, you must know about superheat, subcooling, and other means of determining how much charge is already in the system. You […]
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Honeywell FocusPro – Straight Cool Setup & Wiring
Kalos GM Jesse goes over the setup and wiring of a Honeywell Focus Pro thermostat for a basic system. –Bryan
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Can Pulling a Vacuum too Fast Freeze Water/Moisture?
First, I want to give credit where credit is due. This post is made possible by the fantastic demonstration video by Neil Comparetto that I embedded below. Before you get bored and stop reading, I want to get the conclusion out in the air. Ice can form in a vacuum, but I still advise pulling a […]
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Isolation Diagnosis
There are many great diagnostic tools available to the service technician today, but I haven't found a tool as versatile as the simple isolation diagnosis. There are many ways this concept can be applied, but let's start with some examples so that you get what I mean. Low Voltage Short Circuit Isolation Diagnosis You arrive […]
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5 Simple Service Valve Tips
Service valves are so basic, and we see them with such regularity that we can miss them altogether. Before I give the tips, I want to address the tech who tells the customer it was “probably the service valve” or “the caps were loose” as a plausible reason for a leak without actually making a […]
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Non-Bleed TXV & Trapped Nitrogen
The following is based on a true story. No product was harmed in the making of this tech tip, and some facts may have changed to protect the guilty and because I forgot some of them. We got a job installing a new 1-to-1 split refrigeration case with R448a, and it had a typical thermostatic […]
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Residential System Commissioning (Kalos Meeting)
Residential System Commissioning (Kalos Meeting). Hosted by Bryan Orr. We talk the ABCs – Airflow, balancing and charge. –Bryan Orr
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3-Wire and 4-Wire Condensing Fan Motor Connection
By:Jesse Grandbois Diagram courtesy of Emerson New techs have a common question of how to wire a condensing fan motor for 3 vs. 4 wires. Jesse Grandbois submitted this tech tip to help make it simple. Thanks, Jesse! This tech tip is a quick one on the difference between wiring universal condenser fan motors and […]
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What is “Cascade” Refrigeration?
By:Bryan Orr Photo Courtesy of Emerson What is Cascade refrigeration? “Cascade refrigeration” is a term you will hear more and more over the coming years, and while some of the systems may be very complex, the concept is actually pretty simple. Some refrigerants are well-suited for high and medium-temperature applications, and some are better suited […]
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Double Lugging, A Common Mistake
By:Bryan Orr Connecting more than one wire on or under a single lug or connection point is called “double lugging,” and it is ONLY allowed in line voltage wiring under one condition, according to NEC 110.14: If the terminal, lug, or connector is specifically rated for more than one wire In the case of a […]
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The Two OTHER EPA violations
By:Bryan Orr We all know (or should know) that venting refrigerant is a big no-no and can result in trouble from the EPA. There are many other potential violations, but two of them can easily occur if you aren't thinking ahead at the disposal of mercury and oil. Mercury is found in fairly large quantities […]
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Cleaning Condenser Coils Still Matters
By:Bryan Orr There was a story that came out recently based on an ASHRAE study performed by David Yuill from the University of Nebraska. The study appeared to indicate that condenser coil cleanliness makes no difference on system performance and efficiency. Those of us who have worked in the field know that coil cleaning matters […]
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Humidity Basics
What is relative humidity and dew point and how does it impact human comfort. –Bryan
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5 Capacitor Facts You Should Know
By:Bryan Orr One of the most common parts to fail on a single-phase HVAC system is the run capacitor, so much so that we sometimes refer to junior techs as “capacitor changers.” While capacitors may be easy to diagnose and replace, here are some things many techs may not know: Capacitors Don't “Boost” the Voltage  […]
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Motor Service Factor
By:Bryan Orr “Service factor” is an interesting motor rating that you will see on many motor data tags. It simply means how much additional “work” a motor can do or how much “load” it may be placed under for short periods of time without failure or overload. For example, the FLA or full load amps […]
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Subcooling vs. Liquid Line Temperature
By:Bryan Orr There is a common belief in the trade that the higher the subcooling, the better the system efficiency because lower liquid line temperature means less flash gas. This statement is only partially true and can lead to some confusion among techs. Subcooling is a temperature decrease below the condensing temperature of the refrigerant […]
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The “5 Pillars” of Residential A/C Refrigerant Circuit Diagnosis
By:Bryan Orr Suction pressure, head pressure, subcooling, superheat, delta T. Taking all five of these calculations into account on every service call is critical. Even if you must do further diagnostic tests to pinpoint the problem, these five factors are the groundwork before more effective diagnostics can be done. I would also add static pressure […]
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This is Not a Soft Start
I used to call PTCR devices a "Soft Start". I was wrong.
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Testing Electric Heat – A Cautionary Tale
By:Bryan Orr Travel back in time with me to 2001. I was a young tech, proving my salt out there in the big world of commercial RTU maintenance. One of the steps in the Fall PM list was “test aux heat,” and by golly, that's what I was going to do! I was on the […]
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Work Vehicle Entropy
Have you ever noticed that the more you're required to speed up to get all your work done in a day, the more the cleanliness of your work vehicle suffers? Some techs won't clean their vans, no matter how slow or busy the schedule gets, but most of us prefer a clean and organized vehicle. […]
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4 Basic Energy Rules for HVAC
My favorite “first 4” to teach someone completely new to the air conditioning, heating and refrigeration trade. –Bryan
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What is an ERV?
This quick tip was written by Daniel Andersen in the HVAC School Group. Daniel was one of my early encouragements to make the podcast, even though he refuses to come on himself. Thanks, Daniel! ERV – What is it?  An energy recovery ventilator allows fresh air from outside to be introduced into the conditioned space […]
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Famous Last Words (Before a Callback)
By:Bryan Orr  You've probably heard the famous last words, “Dude, watch this,” before a concussion, burn, shock, broken bones, or some other bodily harm. This phrase has become synonymous with young guys doing something dumb to impress their friends. Technicians have two common phrases that may not lead to bodily harm (although sometimes they might), […]
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How to Diagnose a TXV Failure
There has been much written and many jokes made about the misdiagnosis of TXV (thermostatic expansion valves), and rightly so. This article will cut straight to the point to help those of you who may still need a bit of clarification, and hopefully, we will save the lives of a few TXVs and the pocketbooks […]
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Uncommon Start and Run
I walked into my first real job interview in the HVAC trade. The manager was a guy named Ernie, and he walked me out to the warehouse. Quick warning: guys named Ernie are tough. Don't mess with a dude named Ernie. He walked up to a box, snatched a pen out of his shirt pocket, […]
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Why Discharge Line Temperature is a Useful Reading
Since I started in the trade, we would take discharge line temperature in the winter on a heat pump system. You can easily check the discharge line in the winter, while suction superheat and even subcool can be more difficult to access. The old-timers who trained me would say that the discharge temp will be […]
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What Is Temperature Glide?
  We've all heard about glide, but what is it really, and how does it affect our system? Glide, or temperature glide, is the difference between the bubble point and the dew point of the zeotropic refrigerant mixture. Well, that wasn't very helpful, was it? All we did was introduce new terms without defining them, […]
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Why the 20° Rule is Driving The Internet Crazy
By:Bryan Orr Every year when outdoor temperatures rise, there is a rash of news stories and articles about air conditioning. We had an early heatwave this year, and many people have come out and referred to the idea of a rule of thumb of what temperature you can achieve indoors based on the outdoor temperature; […]
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Multi Tap Primary Transformers
By:Bryan Orr Have you ever seen a low-voltage transformer like the one shown above? It has multiple input (primary) taps for a good reason. It is common to find three-phase and single-phase equipment rated to operate on both 240v and 208v power. That is because three-phase power can either be 208v leg to leg when […]
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Strip Control Wires Properly
Erich Vinson is a tech from Colorado and one of the most entertaining people I interact with online. He wrote this quick tech tip on stripping back the outer jacket properly on control wires, and it happens to also be something I preach. Thanks, Erich. In the first picture (above), you can see what happens […]
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Compressor Performance Analysis
By:Jeremy SmithThis article is written by a regular contributor, experienced rack refrigeration tech, and RSES CM Jeremy Smith. Thanks, Jeremy. Also, there is a podcast out about what kills compressors HERE. A technique that you can use to diagnose compressor problems and help differentiate them from other possible issues is compressor performance analysis. Manufacturers do […]
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Leak Detector Maintenance and Care
By:Bryan Orr A good leak detector is a big investment and one of the more important tools a tech has on the truck. I've had the same leak detector for years, and I've replaced everything on it, from sensors to pumps to the probe. And no, the one shown above isn't mine. One thing that […]
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Short-Cycling
By:Bryan Orr A friend of mine was telling me that a utility had the idea that they could reduce energy consumption by turning HVAC equipment on and off rapidly during times of high load. In their minds, wouldn't it be better to spread out the off time rather than keeping the system off for longer […]
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Sensible Heat Ratio (SHR)
By:Bryan Orr Every piece of air conditioning equipment can move a certain amount of heat BTUs (British Thermal Units) at set conditions. In most cases, during the cooling mode, a portion of those BTUs will go toward changing the temperature of the air, and a part will go toward changing vapor water in the air […]
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500 BTUs per Person Per Hour?
By:Bryan OrrI heard a great presentation by Ron Auvil on VAV systems, and it got me thinking… Can you size a commercial system/perform a block load by the number of occupants? Yes!  No, I'm just kidding. That's crazy talk. There is way more to it than that. However, in a commercial environment, while the building's […]
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Capacitors – Series and Parallel
By:Bryan Orr Knowing how to combine capacitors in series and parallel properly is a great practical field skill to employ when you need to get a customer up and running, but you don't have the exact size. Increasing in size is easy. Just connect in parallel and add the two sizes together. For example, if […]
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HVAC System Design & Load Calculation Course
Duct and system design are two of the BIGGEST needs among technicians, salespeople and contractors. Matt Milton has generously agreed to teach a small online mastermind class on design, load calculation, the math of the trade and much more. While this training may be at “no charge” it certainly isn't FREE. It will require a […]
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Storming the Gates to Trade Education
By:Bryan Orr Before we jump into the stuff that will make folks angry, let's start with some common ground. Most of us can probably agree that the desired result of education in the trades is: Knowing what you are doing and doing it as safely, efficiently, and correctly as possible. If we can agree that […]
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The Difference Between Variable Speed and X13 Motors
By:Bryan Orr First, let's cover the basics. X13 is a brand name for the Regal Beloit/Genteq brand of constant torque motors; there are other manufacturers that make them, but the term “X13” has become pretty much synonymous with the fractional horsepower HVAC constant torque motor. Also, this article is specifically discussing the common residential/light commercial motors. […]
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Condensate Drainage in a High Efficiency Gas Furnace
By:Ben ReedThis article was written by HVAC/furnace technician Benoît Mongeau. Thank you, Ben.     High efficiency (or 90%, or condensing) furnaces use a set of two heat exchangers to retrieve more heat from the combustion products than their mid-efficiency counterparts. Because of this, they generate flue gases much colder than those of a mid-efficiency […]
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Duct Smoke Detectors/Alarms and the Code
By:Bryan Orr Whenever there is a conversation where “code” is involved, it's important to mention that codes can vary depending on the AHJ or authority having jurisdiction. It's becoming more common for governments to lean heavily on the ICC (International Code Council). In the case of HVAC/R, that is the IMC (International Mechanical Code), and […]
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HVAC/R Refrigerant Cycle Basics
By:Bryan Orr This is a basic overview of the refrigeration circuit and how it works. It isn't a COMPLETE description by any means, but it is designed to assist a new technician or HVAC/R apprentice in understanding the fundamentals. First, let's address some areas of possible confusion:  The word “condenser” can mean two different things. […]
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But My Old Unit Worked Fine?!
By:Genry GarciaHow an A/C System got to be Oversized (Maybe) But My Old Unit Worked Fine?! Most of us have heard this at some point. This complaint typically comes from a particularly unhappy customer after the installation of a brand new A/C system. Throughout this article, we’re going to explore the possible root causes of […]
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Ever Hear of Copper Plating Inside the Compressor?
By:Bryan Orr First off, I want to thank Ulises Palacios for taking these photos. He is in the habit of cutting open the compressors he replaces to see why they failed (when possible). I think that's pretty boss. So, why would the compressor have copper plating on the inside? They certainly aren't manufactured that way. […]
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Introduction to SORIT Valves
By:Bryan Orr Photo Courtesy of Parker/Sporlan There are many brands and styles of evaporator pressure regulating valves (EPR), but none as common as the Parker/Sporlan SORIT and ORIT valves. The diagram above clearly shows some of the common applications. An EPR or “hold back” valve maintains a set suction line pressure and, therefore, coil temperature. […]
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What is a Suction Accumulator?
By:Louie Molenda Suction Accumulators A suction accumulator is used to prevent liquid refrigerant floodback to the compressor. A compressor is designed to move vapor refrigerant, NOT liquid, and the accumulator can really help us win that battle. Accumulators are commonly used on heat pumps, transportation refrigeration systems, low-temp supermarket systems, and any place where liquid […]
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Properly Diagnosing a Gas Furnace Pressure Switch
By:Justin Skinner This article was written by boiler technician Justin Skinner. Big thanks to Justin for being one of the rare techs who cares enough to take the time to write something like this. Thank you, Justin! Pressure switches are used in a variety of applications. Generally, they are a normally open switch that closes […]
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A Steam Heating Primer
By:Bryan Orr With cold temperatures right around the corner, it is a good time to brush up on our steam now, and there's no better way to do that than by reading an article by Dan Holohan. This article was written by Dan Holohan and published at HeatingHelp.com HERE. It has been reposted here with […]
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Trane Voyager Gas Screen Tip
Jeff Montalvo shows us a commonly missed issue on Trane Voyager gas package units, how to get to it and what to watch for. –Bryan
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The Why Behind the Lies
This article is written by longtime tech Shaun McCann sharing his experiences with a big problem in our trade. Thanks for this, Shaun.  I started in the HVAC business working for a small commercial union shop in the late '80s. I left that job within a year and worked in the bar and restaurant business […]
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Dirty Coil Clean in Place
HVAC school welcomes Bert to show how to clean an evap in place with Viper. Refrigeration Technologies: www.refrigtech.com   –Bryan
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How to Test Heat Pump Defrost and How Defrost Works
HVAC school reviews how defrost works and how to test it in Carrier and Trane systems. Featuring Jesse Claerbout and Bill Frisbie. Hosted by Bryan Orr.   –Bryan
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TH, TR, and TH/TR Gas Valve Terminals
By:Jesse Claerbout Jesse Grandbois is one of the techs who reads the tech tips, and he wrote a few tips that he wanted to share on some gas furnace control basics. This tip is about the basic terminal designations on a typical 24v gas valve. Thanks, Jesse! Have you ever noticed the TH/TR terminal on […]
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Relative Humidity of Air Below Freezing
By:Bryan Orr I was listening to someone talk about air relative humidity the other day while looking at a psychrometric chart, and he commented that the chart ends down at freezing (32°F) because “all the water freezes out of the air at that point.” I think I made this Jed Clampett face: The psychrometric chart […]
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Electronic Leak Detection DOES WORK
I hear many techs complain about the finicky and ineffective nature of electronic leak detection. So much so that some claim that is is a waste of time altogether. we recently located a leak inside the fins of a ductless evaporator coil, pinpointed to an exact spot using an electronic leak detector. For demonstration purposes, we took […]
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Friction Rate and Duct Design w/ Dr. Bailes (Podcast)
By:Allison A. Bailes III, PhDBryan Orr This episode is very exciting to me because we get to have Dr. Allison Bailes on the show. Today, he shares his knowledge about friction rate and duct design. Allison got his start teaching college-level physics before getting into the building design industry. If you have a forced-air system […]
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Changing a Drain Pan the Easier Way
  Eric Mele is back at HVAC school to surprise us with how he changes a Trane drain pan. Eric shows his method. Featuring Bryan Orr.   –Bryan
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Start Capacitor & Inrush, Facts & Myths – Part #4
By:Bryan Orr Now is the part where we get specific about start capacitors and inrush. If you haven't read the first three parts, please do so before reading this one, or it may not make sense. (You can find Part #1, Part #2, and Part #3 at these links.) I'm going to come out and […]
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Start Capacitor and Inrush Facts & Myths – Part #3
By:Bryan Orr Before we get into the parts that will ruffle some feathers, let's talk a bit about what a “Start” capacitor is and what it does. First, let's review that both start and run capacitors connect between the leg of power opposite of compressor common and the start winding. Even though it seems like a […]
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Start Capacitor and Inrush Facts & Myths – Part #2
By:Bryan Orr Thought Experiment #3 – The Start Winding Has No “Inrush” with a run capacitor only  The name “start winding” is an antiquated term for the single-phase residential industry. It came from the days when CSIR (capacitor start, induction run) motors were still used commonly. In a CSIR motor, the start relay removes the […]
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Start Capacitor & Inrush Facts and Myths – Part #1
This series of articles is one of those that will bug a lot of people because it will go against a lot of what you've been told about compressors, start capacitors, and inrush current. For that reason, I want you to work through a few thought experiments first and maybe even stop and try it […]
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Commercial Contactor Considerations
This tip was created by Jason Pinzak and originally posted on the HVAC Technician's Facebook group. It is reposted here with permission from Jason. Thanks! Contactors are useful in commercial and industrial applications, particularly for controlling large lighting loads and motors. One of their hallmarks is reliability. However, like any other device, they are not […]
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Design Temperature Difference for Chillers 
By:Jeff Neiman I get emails from time to time with questions that stem from the articles or the podcast. This was a great question, but I was not the best person to answer it. I reached out to Jeff Neiman, our resident HVAC School chiller tech, and he answered it. Here is the question: Hello […]
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Do Line Restrictions Cause High Head?
In this video we address the common myth that liquid line restrictions cause high head and we bust it with a few simple explanations. –Bryan
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Oil Management and Diagnosis
By:Jeremy Smith This is a subject that even many commercial guys don’t have to consider. For the majority of equipment, even refrigeration equipment, all that is required for proper oil return is to size the suction line properly, trap the suction line as needed, and allow for proper slope towards the compressor. Then we get […]
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How to Determine the Friction Rate for Residential Duct Design
By:Neil Comparetto This article is written by one of the smartest guys I know online, Neil Comparetto. Thanks, Neil! Recently, I posted a question in the HVAC School Group on Facebook that went like this: “When designing a residential duct system, what friction rate do you use?” As of writing this, only one answer was […]
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Some Important Terms to Know
In my recent classes with my employees at Kalos, we've been going over finding target pressures and temperatures for an air conditioning system. The goal has been to get techs to have “target” readings in mind before they start connecting tools. This step is an important part of being able to “check a system without […]
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No, Recharging R22 Isn’t “Illegal” in the US
If you remember my recent article on the company that went to my friend's house for a PM and did nothing but leave a system quote. Well, it got worse… My friend Josh left them a D-rated review on a popular review site, and the owner of the company responded with… an apology? A bottle […]
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Basic Refrigeration Startup & Commissioning
Let's take a walk through the startup and commissioning procedure of a conventional or “single” refrigeration condensing unit. We’re going to start with a unit that is fully piped in and has been pressurized for leak and strength testing. For brevity, we are going to assume a basic familiarity with industry standards, company and customer […]
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Conditioned Makeup Air
If you don't do a lot of commercial work, you may see a system like the one above and wonder what the heck it is. It is a 100% fresh air unit or a makeup air unit. You will see them more and more as codes start to reflect that balanced ventilation and conditioned outdoor […]
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Refrigeration Temperature Controls w/ Chris Stephens (Podcast)
By:Bryan OrrChris Stephens Chris Stevens from HVACR Videos on YouTube comes onto the podcast and talks about some refrigeration temperature controls basics. You can check out his YouTube channel HERE. Although we have temperature controls in HVAC work, we will see slightly different ones in refrigeration work. The biggest difference is really the temperature itself; […]
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How to Calculate HVAC System BTU Capacity
HVAC school shows how to calculate system capacity using enthalpy. We use the UEI hub kit and some simple calculations to do this. Featuring Bryan Orr. –Bryan
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The “Other” Pressure Switch
The chart above is from a Carrier heat pump, and it lists some common accessories. I have heard this common pressure switch (last on the list) called a low-pressure switch (because it opens on fall in pressure) and a high-pressure switch (because it's in the liquid line), but RARELY do I hear it called its […]
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Careful With That 40VA Transformer
A 40VA transformer is rated for 40 VA or volt-amps on the secondary. For a typical 24 volt secondary, this is simply using Watt's law to calculate amperage. (For more information on Watt's or Ohm's laws, please check out this article HERE.) 40 ÷ 24 = 1.666666 ∞ (round up to 1.67 already) So, you […]
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How to Clean a Condenser Coil
  HVAC school is back to demonstrate how to clean a condenser coil impacted with lint using Viper from Refrigeration Technologies. We show before and after results as well as every step in between. Featuring Jesse and Jayson.   –Bryan
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Oil Pressure Controls
Oil pressure controls, oil failure controls, oil safety controls… They’re a pain in the neck when they trip, and diagnosing those problems can really tax even the best of techs. As semi-hermetic compressors get larger, they can no longer rely on simple splash or “sling” type lubrication strategies where oil is just flung around inside […]
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MacGyver Fix to a Communicating AC System
  My own Carrier Infinity system has had an issue intermittently with communication loss after storms and power outages. I show you a fix that has been recommended to me by many techs to use spare control conductors as a sort of shield.   –Bryan
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How to Read AC Schematics and Diagrams Basics
We walk through some of the basics and most common symbols associated with reading an air conditioner wiring schematic or diagram. –Bryan
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Lifting Techniques Part 4 – Using Unistrut
This is Part 4 series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one, folks. I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life. Disclaimer This article is written by a technician representing his […]
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Lifting Techniques Part 1 – Basics
This is ANOTHER series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one, folks. I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life. Disclaimer This article is written by a technician representing his real-world […]
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Use Your Senses First
A good technician uses their senses before they use diagnostic tools. Is your suction line abnormally cold? Make sure the evaporator coil isn't frozen, and inspect for obvious airflow issues like a dirty filter or evaporator coil. Is your liquid line abnormally warm to the touch? It could be a dirty condenser, condensing fan issue, […]
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TXV Power Element of Surprise
The TXV powerhead or power element is the part of the valve that sits on top of the valve to which the sensing bulb is attached. The powerhead provides the opening force for the valve by translating force from the bulb to a diaphragm in the element that forces the valve open. The sensing bulb […]
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Short 15 – Testing Capacitors, A Practical Approach (Podcast)
By:Bryan Orr In this short podcast episode, Bryan Orr discusses the best practice methods for testing run capacitors in the field. We understand the capacitor to be a voltage storage device. We can benefit from comparing the capacitor to a balloon that inflates and deflates with electrons as the alternating current changes (60 times per […]
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Troubleshooting for HVAC/R – Data Analysis
This article is part 4 of a 5-part series on troubleshooting by Senior Refrigeration and HVAC tech Jeremy Smith Ok, so we've got our data scribbled and scratched out on paper. Maybe a bit of grease, dirt, and oil, too, if you're doing things right—blood if you're doing it wrong. Now, time to take a […]
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Troubleshooting For HVAC/R – Gathering Data 
This article is part 3 in a 5-part series by Senior Refrigeration and HVAC Technician Jeremy Smith. Let's start with step#1 in the flowchart: Gather data. This is why we spend money on those fancy digital manifolds, shiny electrical meters, and other gadgets, widgets, and doodads. It isn't to brag about them on Facebook; it's […]
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The Troubleshooting Mindset
This article was written by Senior Refrigeration tech Jeremy Smith. Big thanks to Jeremy for his contributions to HVAC School and the tech community. Having spent many years in the trade and many years reading posts from techs on forums and social media, a big issue that I see is that troubleshooting is something of […]
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Testing the Leak Rate on Your Micron Gauge Itself
As a technician gains skill they will learn that regularly testing your tools is a huge part of success. It isn't long in the field before techs find out that just because a meter or gauge gives a particular reading it doesn't ALWAYS mean it is correct. Vacuum is one of these areas. Everything in an […]
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How to Evacuate an Air Conditioning System (Fast and Deep Vacuum)
Evacuation Start to finish with some of the best evacuation practices. Click below to see the video. –Bryan
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Danfoss ERC213 Parameters Review (Podcast)
By:Bryan Orr In today's podcast episode, Jonathan Romberg comes on to discuss how the Danfoss ERC 213 works and reviews its parameters with us. Timestamps: 10:30 – Key Features 10:41 – Voltage Protection 10:56 – Compressor Protection 14:43 – Applications 15:15 – App 0 No predefined application 15:28 – App 1 Medium temperature ventilated refrigeration […]
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Drip Loops and Straws
Many of us are aware that X13 and Fully variable motor failure has peaked over the last few years, and I'm sure there are multiple reasons for that. One of the reasons is fairly simple and can be traced back to two simple installation and service practices that can be easily implemented. Seal all air […]
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Keys to Success – Find a Mentor
When I started in the field, I was a 17-year-old helper with one year of tech school under my belt. In other words, I knew nothing. As I've mentioned before, a few experienced techs took me under their wings at different stages, but the most influential was a guy named Dave Barefoot. For whatever reason, […]
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HVAC/R Conductor, Breaker, and Fuse Selection (Podcast)
By:Bryan OrrPhil Barr In this podcast episode, Phil Barr joins Bryan to explain sizing for wires and breakers in HVAC/R work. You will be able to select breakers, conductors, and fuses properly and without confusion. Phil Barr is the leader of the electrical division at our business. HVAC/R equipment may have hermetically sealed motors. Unlike […]
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Heatshrink Crimp Connectors
  Bryan Orr shows us how to setup a transformer with a switch for testing purposes by splicing wires with heatshrink butt connectors.     — Bryan
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How a Relay Works with the 90-340
  In this video I describe and demonstrate the operation, rating and function of a 90-340 relay. It can be used as a fan relay, pump relay or blower relay and much more.     — Bryan
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Duct Leakage Can Be Costly
This tech tip was written by one of the best all-around HVAC minds out there: Neil Comparetto. I think that we all can agree that duct leakage is not ideal. Our job is to condition the space. If we can’t control the air, that becomes difficult. On top of that, anytime the ducts leak, you […]
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Low Ambient, Condenser Flooding and Headmaster Valves Podcast Companion
By:Bryan OrrJeremy Smith Today, Jeremy Smith joins us to discuss low-ambient conditions and controls, condenser flooding, and headmaster valves. He has also given us a companion article on those subjects, which you can read below. Download the podcast directly HERE. As always, if you have an iPhone, subscribe HERE, and if you have an Android […]
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Prevent Compressor Murder Part 1 & 2 w/ Emerson (Podcast)
By:Trevor MatthewsBryan Orr Part 1: In today's podcast, we talk with Trevor Matthews with Emerson. He tells us about the causes and prevention of air conditioning and refrigeration compressor failure. Most compressors don't die a natural death… they're murdered. Of course, that's to say that installation and maintenance play a major role in the compressor's operation […]
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What Does “Air Free CO” (Carbon Monoxide) Mean?
  Almost everyone knows that CO (carbon monoxide) is really nasty stuff and nothing to play around with. Humans will often begin exhibiting symptoms of CO poisoning at 200 ppm (parts per million) of CO in a space. Studies have also shown that the effects of CO exposure can accumulate over time, resulting in health […]
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You’re Grounded
One of the most common questions we get from techs is about using a voltmeter to diagnose a high voltage circuit. It's especially tricky when a tech is used to working on a low-voltage or 120V circuit, where there is a clear “hot” side of the circuit and a clear “grounded” side of the circuit. […]
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Furnace Commissioning Part 2 w/ Jim Bergmann (Podcast)
By:Jim BergmannBryan Orr In the second part of this podcast series, Jim covers the basics of furnace commissioning in more detail with some common-sense practices. (Listen to Part 1 HERE.) Even though installers set up a furnace system, the technicians help with the equipment startup and commissioning. That way, two parties can ensure that the […]
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Hydronics GPM Calculation and More…
This tech tip was written by a friend of HVAC School, Brian Mahoney. He is an HVAC instructor at Western Suffolk BOCES/Wilson Tech. Thanks, Brian! The podcast on delta T for A/C the other day got me thinking about the formula I learned in school about calculating the GPM of a hydronic system. We will […]
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Watch It, Hercules 
I watched an instructional video the other day where the guy kept palming his gauge manifold and CRANKING down on the valves when he closed them. I've seen techs use channel locks—and even vise grips—to tighten down their gauges “just in case” when they have a hard time finding a leak or a vacuum that […]
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The Case for Checking the Charge Without Using Gauges
Jim Bergmann and I recorded a podcast for HVAC School that covered when and how to check the refrigerant circuit without connecting gauges. Listener Joe Reinhard listened several times and wrote up this summary of what he gained from the episode. I edited it lightly, but most of this is his work. Thank you so […]
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Does Nitrogen Pressure Change with Temperature – Practical Application of Gas Laws
The gas laws. We all learned about them in school and promptly forgot all about them. I really think that we need to dig our books out, dust that information off, and work to understand and apply it. Many will say that nitrogen pressure doesn't change with pressure like other gasses. That is false, but […]
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Intro to Pneumatic Controls w/ Jim Loring (Podcast)
By:Bryan Orr In today's podcast episode, Bryan talks to west-coast commercial tech Jim Loring about pneumatic controls and variable air volume (VAV) systems. People sometimes confuse pneumatics and hydraulics. Hydraulics use liquid to provide pressure; conversely, pneumatics use air to provide pressure. Pneumatic controls use a bit more energy than other controls, but they are […]
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Floating Suction and Head and Rack Refrigeration w/ Jeremy Smith (Podcast)
By:Bryan OrrJeremy Smith Jeremy Smith goes over floating suction and floating head refrigeration strategies. He also talks a bit more about low-ambient equipment operation. Floating suction controls developed when we started using low-pressure controls on rack refrigeration. As the electronics advanced, we developed controls that could control temperature, which impacts pressure as well. Nowadays, controls […]
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The Extension Cord Puzzle
Suppose you have two extension cords. One is a nice, thick #10 50′ cord with good ends, and the other is a crappy #14 25′ cord. Unfortunately, you need to connect them both to get to your drill 75′ away. Which do you connect to the plug, and which to the drill? Come up with […]
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What 2018 Holds for Techs
We don't work in a trade of dreamers and unrealistic New Years' resolutions. We are doers who know that nothing worthwhile comes easy, and 2018 is no different. We have some “threats” entering the residential segment of the trade. Amazon and Google are looking to make a bigger entry into the home services trades, standardizing […]
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EcoBee Thermostats and Dehumidification
  Dehumidification features have been common on residential systems ever since the introduction of variable speed blower motors. The system is set up so that the blower can produce less CFM per ton when the latent load (humidity) in the space is higher than the setpoint relative humidity. Slowing the blower increases moisture removal by […]
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Be Careful When Jumping Out a Blower
We've seen it before. A tech diagnoses a failed blower relay or board. They leave the blower jumped out by putting a terminal multiplier on the common terminal of the relay/board and connecting the fan speed tap right to power. There can be an issue with that. Some electric heat fan coils have a heat/blower […]
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Leak-Free Systems w/ Bill Johnson (Podcast)
By:Bryan Orr Bill Johnson is one of the great educators and writers of our time in HVAC/R. In this podcast episode, he shares some information about his career and some of his top tips on keeping systems leak-free. Bill began his work on leak-free solutions by using Glyptal on centrifugal compressors. The Glyptal would harden […]
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Ice Machines – Cuber, Flaker & Nugget Basics
There are several types of ice machines, but in this article, we will focus on cuber style and flaker or nugget style. Both types produce ice, but the process of freezing and harvesting is a little different. The application in which the ice will be used will determine what style of machine is needed. I […]
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Furnaces – Introduction and History w/ Jim Bergmann (Podcast)
By:Jim BergmannBryan Orr Jim takes us all the way through the history of furnaces, from the Stone Age when he was a child to modern modulating condensing types. The goal of a furnace is to move heat, so a furnace uses heat exchangers to facilitate heat transfer. Furnaces have primary and secondary air. The primary […]
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Boiler Basics Part 2 – Components
This article is the second in a series on boiler basics by senior boiler tech Justin Skinner. Thanks, Justin. There are many types of boilers that do many different things, but almost all of them have some of the same basic components. It's partially because regulatory agencies require them, and other times, it's because they […]
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Boiler Basics Part 1 – Types and Components
This series of articles is written by senior boiler tech (and all-around swell guy) Justin Skinner. Thanks, Justin. There are quite a few different types of boilers out in the world. They come in all shapes, sizes, pressures, and types of fuel burned. I'm going to go over some of the more common ones, their […]
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Ductless Maintenance Steps – Part 1 (Podcast)
By:Bryan OrrJesse Claerbout Ductless expert Jesse Claerbout talks about his best practices for maintaining ductless air conditioners and heat pumps. This episode is part 1 out of 2. Ductless maintenance can be a bit more extensive than regular split system maintenance. Ductless filters are plastic; they are not high-MERV and can simply be washed off […]
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Run Capacitor Facts You May Not Know (Podcast)
By:Bryan Orr In this episode, we cover some common misconceptions about run capacitors, some easy ways to test them, and some tips on working with them. A run capacitor is a power storage device; it contains oil to dissipate heat and some thin metal plates wrapped in a spiral. Capacitors also contain plastic insulation between […]
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Giving Static for Failing to Take Static 
This article was written by Christopher Molnar, a licensed Florida mechanical contractor. While I'm not personally a practitioner of the “check static every time” doctrine, I certainly appreciate Chris and his passion for this topic. Thanks, Chris! Why Check Static Pressures on EVERY call You wouldn't go to the doctor’s office and walk away without […]
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Drains and Double traps
Double traps are no good. That's the end of this tech tip. Okay, here's some detail: Anytime your drain goes up and down more than once, you have a double trap UNLESS you place an air vent between the two traps that vents ABOVE the drain inlet. The double trap causes drainage issues because air […]
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A Case For Wireless Refrigerant Probes
Photo by Brad Hicks at HVAC in SC Right off the top, let me state something loud and clear: The tool does not make the tech. Let that sink in before you move on. A good tech has a solid understanding of WHY they are doing what they are doing, the basic math of the […]
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Commercial Refrigeration for A/C Techs w/ Dick Wirz (Podcast)
By:Bryan OrrDick Wirz Dick Wirz, author of Commercial Refrigeration for Air Conditioning Technicians, talks about making the switch from A/C to refrigeration. Dick Wirz is an advocate for using rules of thumb, which is a controversial position. However, rules of thumb are an excellent way for A/C techs to dip their toes into the refrigeration […]
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MeasureQuick Launch Is HERE
For those of you who follow the podcast, you know how excited I am about the new MeasureQuick app and what it will do to help technicians make better measurements and diagnoses. The app is NOW AVAILABLE on Android and will be available within hours on iOS (Apple). To find out more and to download, […]
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Change O-rings, Not Hoses
Make the most of those expensive refrigerant hoses.
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Don’t use Tank Caps on Systems
This is a video tech tip from our friend Brad at HVAC in SC. In this video, Brad demonstrates that using a cap off of a refrigerant tank on a system can depress the Schrader core on the system in some cases. Make sure to use proper caps that have seals or brass flare cones. […]
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HVAC/R Evacuation Quiz
Take Our Basic Electrical Circuits Quiz to check your knowledge on Electrical Circuits. You could also check our videos on the topic.
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EPR valves 101
I don't do much in the way of “rack” refrigeration. However, I recently had a conversation with experienced rack refrigeration tech Jeremy Smith, and he got me thinking about EPR valves. I've heard EPR (evaporator pressure regulator) valves called suction regulators or hold back valves. In essence, they hold back against the suction line to […]
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Purge Your Hoses
The title says it all. It should be one of the first things you learn when you started. However, I have seen a lot of experienced techs who seldom (if ever) do it. When connecting to a tank, purge your hose by cracking the center connection at the manifold for a second. When connecting to […]
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Common Duct Design Mistakes w/ Jack Rise (Podcast)
By:Bryan Orr In this episode, Jack Rise talks about duct design regarding ACCA manual D, friction rate, face velocity, duct velocity, and what is ACTUALLY wrong with flex duct. Manual D causes a lot of confusion for technicians, and most techs have a limited understanding of it anyway. When determining a blower wheel for commercial […]
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Check The Charge Without Gauges – Podcast
By:Jim BergmannBryan Orr In this episode of the podcast, we talk about gauges. Jim Bergmann from Redfish Instruments and the MeasureQuick app gives us all a detailed explanation of how to check a charge without using a gauge manifold. (That's not clickbait; if you've already connected gauges to a unit once, you can probably check the charge […]
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Evacuation 101 w/ Jim Bergmann (Podcast)
By:Jim BergmannBryan Orr In this episode of the podcast, Jim reviews the basics of evacuation and dehydration. He also covers hoses and vacuum gauge placement. Evacuation may just seem like a method to suck air and water out of a system. However, it is an intricate science that lacks a lot of detail in most […]
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When Will Techs Be Replaced By Robots? (Podcast)
By:Bryan Orr In this episode, Bryan talks with HVAC products designer Adolfo Wurts about technology, automation, and the coming robot apocalypse. Automation is a fear in many industries, and the HVAC industry isn't alone. Today, we talk about how instrumentation and AI technology may develop and what that will mean for the future of the […]
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Psychrometrics Basics w/ Jamie Kitchen Podcast
By:Bryan OrrJamie Kitchen In this episode of the podcast, Jamie Kitchen from Danfoss talks about wet-bulb, dry-bulb, relative humidity, dew point, enthalpy, and latent heat. These are the building blocks of psychrometrics, which deals with human comfort as it relates to temperature, humidity, and heat loads. Humidity is water vapor in the air. As the […]
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Hard Start Types and Applications Podcast
By:Bryan OrrJames Bowman In this episode, Bryan speaks with James Bowman from Rectorseal about hard start kits, PTCR devices, run capacitors, compressor overheating, and the Kick Start product. We also go pretty in-depth on potential relays and how they operate. Hard start kits are mechanical potential relays connected to a capacitor, and they aid in […]
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EPA Section 608 Changes Every Tech and Contractor Needs to Know (Podcast)
By:Bryan Orr In this episode of the podcast, Jeremy Arling from the EPA comes on and answers some common questions about the new rule changes that affect recovery, leak repair, recordkeeping, and evacuation on HVAC and refrigeration systems. EPA 608 rules regulate the actions that technicians must take when it comes to refrigerants and the […]
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What Size Wire Does this Condenser REALLY Require?
By:Bryan Orr In this episode of the podcast, we talk about condenser wire sizing considerations, ampacity, temperature, conductor sizing, voltage drop, and why a #10 wire doesn't always require a 30-amp breaker. There's usually nothing wrong with OVERSIZING a wire or conductor. However, you still need to know which wires are safe for operation and […]
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Refrigerant Recovery Practices
Recovery is the removal of refrigerant from a system to either store and send in for recycling or to reintroduce back into the same system. Here are some top tips – Make sure your tank is empty and evacuated to 300 microns if you plan to return the refrigerant back into the system. Never mix […]
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Combustion Basics w/ Benoit Mongeau
By:Bryan Orr In this episode with BENOÎT MONGEAU, we talk about the components of combustion and what to consider when testing it on a fuel-burning appliance. Combustion requires fuel, oxygen, and a heat source in a correct balance. We call that series of requirements the “combustion triangle.” Once combustion occurs, it is self-sustaining. However, removing […]
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Splicing Wires – Bad, Good, Better, Best
There are many acceptable methods for making a wire splice and you need to consider many different factors when making a splice. Here are a few considerations. High Voltage vs. Low Voltage – If the connection is 24V or less it USUALLY has fewer NEC (National Electrical Code) rules and regulations about how the connections are […]
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False Negatives on One Capacitor Test
I have spent the last few days checking run capacitors on various systems with several different meters, and this is what I found: #1 – Comparing Start wire amps against Run + Common under the clamp together is meaningless as a practical test. I used this test on 3 different systems with 3 different meters […]
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An even EASIER way to check capacitors
In a previous article, we covered the standard way to check capacitors under load. I am now going to give you an even easier test. A properly functioning PSC (permanent split capacitor) or CSCR (capacitor start capacitor run) motor should have a power factor of very close to 1 if they have a properly sized […]
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UV Lights
A quick note about UV lights: they work like sunlight in that they prevent and kill many types of bacteria and fungi when exposed to the light on surfaces. They do not generally do a great job of killing spores suspended in the air stream. UV lights are great at killing yucky stuff on surfaces […]
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Testing Run Capacitors the Smart (and Easy) Way
When testing a run capacitor, many techs pull the leads off and use the capacitance setting on their meter to test the capacitor. On a system that is not running, there isn't anything wrong with this test. However, when you are CONSTANTLY checking capacitors as a matter of regular testing and maintenance, that extra step […]
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Condensing Temperature, Condenser Split, and Subcool
By:Bryan Orr In this podcast, Bryan talks about condensing temperature, condenser split, and subcooling. All three of the values are proportional. If one changes, all three of them will change. Saturation is also a critical concept that relates to all three of those, so we also cover those relationships. As you remember, a condenser rejects […]
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Why You Need a Torque Wrench (or Two…)
I’ve got a confession to make. I'm “that guy.” Call it OCD, call it being anal-retentive, but I'm always making an effort to be as technically correct as possible. One aspect of that effort has been the use of torque indicating or torque limiting tools when tightening fasteners. It started after I put new valve […]
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R22 Retrofit Tips
The price of R22 is getting ridiculous, and one of the #1 requests I have been getting is for recommendations on other refrigerants to use in place of R22 and best practices, so here we go. No, you shouldn't mix There are NO refrigerants that you are supposed to use to top off an R22 […]
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Hard Start Kits, Stay Brite #8, AHR, and More
By:Bryan Orr In this episode of the HVAC School Podcast, we talk about some cool technologies and controversial tools. Joe Shearer joins us to talk about hard start kits. Some people believe that hard start kits are only suitable for one-time use, but Joe and Bryan believe that there's a lot more to it than […]
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Leak Detection on Large Systems
Imagine, if you will, a 20-year-old kid. He has no formal training in the HVAC/R field, only ride along “training” and book learning as he reads along with his journeyman father with whom he's riding. One stormy summer evening, a service call comes in for an ice cream freezer down. After calling and talking to […]
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No, It’s NOT a Ground!
I was walking around at the AHR conference today, and I stopped at the booth of a popular hard start kit manufacturer (especially popular with white-shirt sales techs). I listened to the guy behind the booth “training” some municipal maintenance techs on the use of his hard start kit. (To be fair, I actually think […]
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Boiler Basics Part 4 – Piping
Please note: There have been some legitimate questions about a few of the points in this article and the diagrams. While Justin Skinner is an experienced tech and totally qualified to write this article, we will be specifically looking into the question of the best location of the circulator pump and addressing the “point of […]
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Chillers for the Chillerphobic – Podcast
By:Bryan Orr   In this episode, we talk with Jeff Nieman about chillers and how they work. For those of you who primarily work in residential or light commercial HVAC, chillers may be unfamiliar at best and terrifying at worst. However, centrifugal chillers' parts are actually quite similar to those of HVAC units. They have […]
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Oil Nozzles
This article was written by Senior Boiler Tech Justin Skinner. Thanks, Justin. Oil burner nozzles are present in most forced combustion air burners. They are used with an oil pump to atomize fuel oil and allow it to burn. Atomizing is raising the pressure of the fuel and forcing it through the nozzle. Essentially, the […]
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Venting for High efficiency Gas Furnaces – Part 1 Materials
This article was written by senior furnace tech Benoît (Ben) Mongeau. Ben hails from the frozen tundra of Ontario, Canada, where high-efficiency gas furnaces are commonplace. While some codes and practices may be different from the US, I find that most of it is common sense and translates pretty well. One glaring difference between Canada […]
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Boiler Basics Part 3 – Steam
This article was written by Senior Boiler Tech Justin Skinner. Thanks, Justin. Steam plays a very important part in all of our lives, whether we know it or not. Virtually every article of clothing and accessory you are wearing right now relied on steam for either manufacturing or packaging. Hospitals use large steam boilers for […]
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Lifting Techniques Part 5 – Really HEAVY Stuff
This is Part 5 of a series by Senior Refrigeration Tech (and prolific writer) Jeremy Smith. Pay attention to this one, folks. I know rigging and safe lifting practices may be boring to some of you, but it could very well save your back or your life. Disclaimer This article is written by a technician […]
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Evacuation, Recovery, and Dehydration Facts Podcast
By:Bryan Orr In this episode, Bryan covers evacuation, recovery, and dehydration. Evacuation refers to putting a vacuum pump on the system and pulling it down. We use a few different measures of vacuum, including inches of mercury (“Hg) or microns (millionths of a meter of mercury). We use such small units to measure a vacuum […]
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Combustion Analysis w/ Stephen Rardon – Podcast
By:Bryan Orr In this episode, Bryan talks to YouTube star Stephen Rardon about combustion analysis. In Florida, we mostly have A/C units and heat pumps. High-efficiency furnaces are not in our wheelhouse, but furnaces are more like A/C units than you would imagine. Stephen Rardon makes some excellent comparisons between the two. For example, you […]
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Refrigeration Basics Quiz
Test your skills to see if you are a refrigeration basics pro… or a parts changer
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Heat Pumps, Reversing Valves, and Defrost Podcast
By:Bryan Orr In this episode of HVAC School, Bryan covers the basics of heat pumps. Heat pumps are common technologies in Florida. They reverse the sequence of the typical refrigerant circuit: the indoor coil can become the condenser, and the outdoor coil can become the evaporator. Heat pumps can achieve that transition via a reversing […]
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Something You May Want to Consider on Every Call
There are a few important things that I suggest checking on every service call to reduce callbacks and increase customer satisfaction. One of them that often gets missed is preventing wire rub outs. One of my area managers and experienced tech Jesse Claerbout shot a video showing the simple step he takes to prevent major […]
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The Basics of Moving Heat (Thermodynamics)
By:Bryan Orr In this episode of HVAC School, Bryan talks to some apprentices about basic thermodynamics. That is the fancy scientific way of saying that we're moving heat. The way we think of “hot” and “cold” is relative to our comfort. However, the scientific concepts of “hot” and “cold” are very different from our relative understandings […]
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Basic Electrical Theory
By:Bryan Orr In this episode of HVAC School, Bryan talks to his sons about basic electrical theory. Electrical theory normally requires trigonometry, calculus, and all of those fun maths. However, the basics are so easy that a 12 and 14-year old can figure it out. Electrical theory follows many of the same principles as thermodynamics—however, […]
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Diagnosing & Replacing a Compressor
By:Bryan Orr In this podcast episode, Bryan goes over best practices for diagnosing and replacing an A/C or refrigeration compressor.  When testing for a shorted compressor, make sure the compressor is isolated from all of its circuitry. You would see low ohms to ground in a shorted compressor. Do NOT measure from winding to winding […]
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Refrigeration Tips For A/C Techs
By:Bryan OrrJeremy Smith In this episode of the HVAC School Podcast, Bryan talks with Jeremy Smith about refrigeration tips, terms and processes. They also cover the similarities and differences between A/C and refrigeration. Being on-call as an A/C tech is not all that different from being on-call as a refrigeration tech. Similarly, the principles of […]
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Furnace Sequence of Operation
By:Bryan Orr In this episode, Bryan talks to Justin Skinner about the standard gas furnace sequence of operation. Regardless of the furnace type, it all begins with a heat call on W… Then, the furnace checks the safeties to make sure ignition is possible and safe. If all systems are a go, the inducer motor […]
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Blower Relay, Electric Heat Tips and Mistakes
In this video we talk about – Common misunderstandings about blower relays How Blower relays connect to sequencers How Sequencers and other relays connect to electric heat Mistakes techs make that cause major damage and high power bills How to replace a blower board with a universal 90-340 relay If you have an iPhone, subscribe […]
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Basic Refrigeration Circuit
The following quiz contains 12 questions that will test your knowledge of the basic refrigeration circuit.
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