#hvac

In 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 typically […]

Enthalpy is easy. It's just a state function that depends only on the prevailing equilibrium state identified by the system's internal energy, pressure, and volume. It is an extensive quantity. Simple. Like most things, the scientific definition is as clear as mud. In HVAC/R, we use enthalpy measurement to come up with the total heat […]

I was talking about dry contacts with one of my techs, and he looked at me like I had three heads—and one of them was on fire. So, I figured it would be good to cover the difference between wet and dry contacts in a tech tip. Basically, “dry” contacts are switches with no shared […]

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, you might […]

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 reach the […]

First, let's state the obvious and clear the air a bit. The photo above is SUPER CHEESY! But this story is about three bad techs who don't know it, so a photo of three models clearly posing in clean clothes makes as good of a proxy for a bad tech as anything else. First off, I'm […]

Even though there will almost surely be a healthy demand for HVAC service businesses, any service business is still at risk of going under. Most of the trouble comes down to money mismanagement or misunderstanding. The good news is that the risks are avoidable with proper education and care. We aren’t accountants or lawyers, but […]

Most of the content in this article is based on Alex Meaney’s contribution to the HVAC School podcast in the October 2nd, 2020 episode: “How to Get The Most From Online Education,” which you can listen to HERE. Attending a class from your bedroom or home office sounds very convenient, right? That was probably what […]

Nomenclature on HVAC/R equipment is a sequence of numbers and letters a manufacturer uses to speak directly to the technician. Lots of initial upfront information is handed to the technician by the manufacturer the moment the technician reads the nomenclature in the model and serial numbers. So, how do we make sense of these seemingly […]

 In this short podcast episode, Bryan explains electronic expansion valve (EEV) types. EEVs perform the same function as TXVs, but they operate electronically, not mechanically. The EEV makes sure that the evaporator is full of the right amount of refrigerant at saturation; it doesn't just affect evaporator pressure. We don't want high superheat (due […]

 In this short podcast episode, Bryan talks about when to switch to emergency heat. He talks about coefficient of performance (COP) and how it's a deciding factor when to run emergency heat, which is when a system ONLY runs the backup heat; it doesn't use it as supplementary heat. When we have a heat […]

 In this short podcast episode, Bryan talks about the four different combustion venting categories for gas appliances as set by ASHRAE and where you'll see them. He also shares some notes about pressurization. These categories deal with the pressurization and temperature ranges of the vents. Category 1 venting is used for old-school open-combustion gas […]

 In this episode of the HVAC School Podcast, Bryan Orr and Trevor Matthews delve into the importance of setting goals, focusing on them, and taking actionable steps to achieve them. They emphasize that goal-setting is crucial for personal and professional growth and that it requires introspection, prioritization, and sacrifice. Trevor shares his experience of […]

 Shelby Breger, co-founder of Conduit Tech, joins Bryan Orr on the HVAC School Podcast to discuss her company's innovative lidar-enabled design and sales software tool for HVAC contractors. Conduit Tech's software utilizes lidar sensors in iPads and iPhones to scan homes and create 3D models and 2D floor plans. It overlays load calculations factoring […]

 In this short podcast episode, Bryan dives into some belt talk, including some bits about pulleys and sheaves. He also shares some belt tensioning tips for your next commercial HVAC job. Belts are less common than they used to be, but we find them in ventilation fans, RTUs, and AHUs. Squealing belts indicate slippage, […]

 In this episode of the HVAC School Podcast, host Bryan Orr speaks with Chris Hughes of The Energy Conservatory (TEC) about using the Roomulator card and DG-8 manometer for room pressurization testing. Chris provides background on how he came up with the idea for the Roomulator. He wanted an easy way for technicians to […]

 In this short podcast, Bryan dives into a gas heating topic: primary & secondary air in combustion. Primary air is the air and oxygen content that enters the furnace BEFORE combustion. In older furnaces, prior to induced combustion, air was drawn in through the front. These older furnaces had adjustable shutters that we could […]

 In this solo podcast, Bryan provides an introduction to heat pumps, explaining the basics of how they work and key considerations in a way that is easy for anyone to understand. He starts by reviewing some core HVAC principles – that heat moves from higher temperatures to lower temperatures, the three main methods of […]