Tag: hvac

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 three models clearly posing in clean clothes makes as good of a proxy for a bad tech as anything else.

First off, I’m not being negative about the trade or making fun of people, the point of this story is to identify some traits that many of us may exhibit or see in others techs and it can be hard to identify our own issues or issues within your organization. See if any of these techs sound a LITTLE TOO FAMILIAR and maybe we can learn something. Before you ask… No, these are not real people…. probably… maybe

Randy the Drama King

Randy, like most dramatic people who work in the trades, doesn’t see himself as being dramatic. He just thinks he is being constantly disrespected by management and co-workers and customers are crazy and the dispatcher is out to get him and it’s always about to rain and that ladder (and every ladder) looks unsafe.  These things aren’t DRAMA they are FACTS in Randy’s world and if you question this reality you get added to the long list of people who are disrespecting him.

Randy starts conversations with customers with phrases like “you aren’t going to want to hear this” or “Do you want the good news or the bad news”. He also tends to pass blame to his coworkers or his company because they are just clueless and he knows what’s REALLY going on.

Randy is actually a good tech, but he get’s in a lot of conflicts with coworkers, customers don’t always like his negativity (or as he calls it “being honest”) and he is inefficient and largely unpopular with other techs and management. Randy knows people think poorly of him because everyone is conspiring against him with that blankety-blank dispatcher Donna!

Randy always feels persecuted by the people around him and usually has something negative or conspiratorial to share about every topic. Politics, The weather, customers, co-workers, spouses… you name it.

Here is a test you can take to see if you might be a bit of a Randy

  • You have more than 5 people you are ticked off with or avoiding at any given time
  • You consistently see “danger” around you that nobody else sees
  • During work hours you have multiple conversations over 5 minutes with others about things that are “wrong”
  • You use a lot of negative and fear-inducing language with customers

If you find you are allowing negativity and drama get to you the best practice is to give yourself a break from negative speech. Like your grandma used to say, “If you don’t have anything nice to say”. Negativity is a hard habit to break but the best time to start is now and the best antidote for negativity is gratefulness.

Bob the Excuseful  

Yes, excuseful is a word… I made it up and I like it.

Bob is confident that he would be able to do his job if he was just given the proper training and tools and enough time to do the job and enough sleep and wasn’t forced to work these ridiculous hours. Bob often wonders if he should go back to school and get his degree in …. something and all the courses he would take if his cheapskate boss would just invest in him.

Sure he was given a book and sent to a seminar last month but that was all THEORY, he is a hands-on learner and he CANNOT learn from books or videos or seminars or anything unless he can get his hands on it.  Once he DOES get his hands on it he can’t be held responsible for any mistakes he makes because he has to be SHOWN what to do and how to do it and if he isn’t SHOWN how can he be held responsible? Now, when he is shown, he is a hands-on learner so he can’t learn things by being shown… he needs to do it himself.

His truck may be a mess but he would clean it if he ever had time with these ridiculous hours but in the slow season that is his one time of the year to relax, you can’t expect him to take his own time during the slow season to clean his van can you?

Here are some indications you may be struggling with a bit of Bobish excusefullness

  • You feel jealous when others succeed  and immediately give some reason why they have an advantage over you
  • You read fewer than 5 books last year but still feel like your lack of education is someone else’s fault
  • You find yourself using “hands-on learner” as a reason for failing to understand something
  • When you don’t understand something you call or text someone rather than looking up an answer yourself
  • You have a sense that your lack of progress is due to a lack of “opportunity”

The best way to stop making excuses is to begin living and working with what old-timers called “grit” or “gumption”. This means doing whatever it takes to solve problems, making excellence a goal and going after it no matter the barriers. Start by reading and learning on your own, don’t wait for someone to show you or tell you, go get it yourself.

Todd the Careless

Todd knows he is just forgetful, he TRIES to remember to tie down his ladder and put the caps back on and close his back doors on his van but he just forgets sometimes OK!

Sometimes Todd get’s defensive when other techs call him out for leaving the panel off or “forgetting” to clean the drain, but usually Todd just apologizes and says he will do better next time, but he knows he won’t because he didn’t do it on purpose, it just …… happened.

Some of the “Grouchy” old techs have told him that doesn’t seem to care about his job, but they are WRONG! (in Todd’s mind) he does care, he just has other things going on in his life and in his mind and sometimes accidents happen… like the time he stepped through the attic ceiling, or the time he slipped on the ladder, and that one time he rear-ended that car in the parking lot… oops

You may be a Todd if ….

  • You regularly make mistakes where you “just forgot”
  • You find yourself looking at your phone, texting and using social media during the workday
  • Your mind is preoccupied with personal matters during work and while driving

We have entered a new era of carelessness due to the advent of smartphones, social media, and texting. Many of us find our minds constantly distracted by things other than work during the work day and it leads to poor outcomes, mistakes and safety hazards. everything from climbing a ladder, to driving, to filling out a service call requires ATTENTION and distraction can lead to costly and dangerous mistakes. The best advice is to put the distractions way during the work day… unless it is reading this article. Just remember to put the panels back on and run test the equipment when you are done.

— Bryan

 

 

 

 

 

 

Air-to-water pool heat pumps are seeing more and more popularity in the climates that can support them over the more traditional gas and electric pool heaters we usually see.  While they definitely contain some familiar operating principles to an air-to-air heat pump, there are some striking differences in the way the heat is transferred as well as how the components are controlled and protected.

 

Heat Exchange in a Pool Heat Pump

Most residential and light commercial heat pumps are packaged systems, containing all but a few necessary components for it to perform its duty of heating the body of water it serves.  We have some strong similarities with an air-to-air system: a large air coil mounted on its perimeter, an outdoor fan to perform heat exchange over this coil, a compressor to pump refrigerant, and a metering device to control the capacity delivered to the evaporator.  On many, you’ll also find a liquid receiver and / or a suction accumulator to make up for the wide temperature loads they’re designed to handle.  The system gets interesting with the introduction of a water coil.

There are two different types of common water coils in use currently.  The first one we’ll go over is the coaxial coil.  This is a coil inside a coil, designed to rapidly exchange heat between the refrigerant and water we’re adding heat into.

The mainstay material for coaxial coils has been a unique alloy of copper (Cu), nickel (Ni), iron (Fe), and manganese (Mn), known as cupronickel (pictured above.)  It has all of the pressure characteristics of copper, but with the added benefit of being much more resilient to corrosion from a variety of sources.  Interestingly, all of the “silver” U.S. coinage is made with this same alloy.  Titanium (Ti), while less noble than copper, has also entered the market as an alternative to cupronickel with a lighter weight and greater corrosion resilience.  However, these coils are often larger in size given titanium exchanges heat less effectively than copper and is much more difficult to work.

Coaxial coils are fairly simple in their construction.  The outside of the coil carries refrigerant, while the inside handles the water.  These coils are designed to counterflow the two mediums in order to exchange heat rapidly.  The inside of the coil is also rifled, creating a swirling effect that helps this process along further (see the diagram below.)

An alternative heat exchanger that’s used is the tube in shell coil, which, just as its name implies, is a refrigerant coil inside of a water tank.  Counterflow makes an appearance here as well, passing the influent water across the effluent refrigerant.  Depicted below is a dome-style tube in shell titanium coil.  This particular coil is found in a water-to-water pool heat pump.  Note how the copper adjoins to the titanium using a ferrule just before entering the coil.

 

Safeties and Controls

Pool heaters are thermostatically controlled just as you would expect.  In most cases water temperature is measured with a thermistor inserted into a temperature well that contains a heat conductive paste to provide the most accurate measurement of the water flowing across it.  These are made of either a polymer composite, brass, or copper.  They also double as a safety measure on systems employing cupronickel as they will breach first should a chemistry imbalance present in the pool water, alerting service persons before a water flooded refrigeration system occurs.

Another unique safety we’ll discuss is the water flow switch.  This switch is akin to the pressure fall switches found inside induced draft furnaces.  They contain a pressure sensitive diaphragm connected to a normally open switch that closes when pressure is applied, thus informing the unit control when water flow is absent.  Just like air-over designs, a refrigerant coil with no water to transfer heat into can be severely detrimental to the compressor it serves.  High discharge pressures can result, leading to premature mechanical failures.  While a high-pressure refrigerant cutout may also be employed, this water flow safety acts as a first response to protect the system from catastrophic damage.  This will prevent the system from operating whether the pool pump is off due to scheduled downtime, a power interruption occurs, a pool filter becomes impacted, or any other condition that ceases water flow.

A majority of systems contain an internal water bypass that controls how many gallons per minute are allowed to flow through the condenser coil.  Too much supply water and the temperature rise will be too low; too little, and the temperature rise will be too high.  This is one of the most important contributing factors to efficiency in an air-to-water system.  These bypasses are usually preset by the factory without any adjustment required in the field.  Be aware that there will likely be an external bypass as well which can wreak havoc on the heater operation should it be tampered with.  Remember to check these first if the water flow switch is keeping the system off!

Similarly to air-to-air systems, air-to-water heat pumps will occasionally require defrost cycles during cold weather. This is achieved primarily by demand defrost with a temperature sensor affixed to the air coil.   Care needs to be taken with the placement of these sensors, as a quickly frosting circuit can produce short cycling of the equipment.  Pools and spas tend to lose heat very quickly, and recovery can become impossible with excessive defrost cycles during cold days.

Finally, many heat pumps will feature a method to pair multiple units to cycle on and off together to provide extra capacity for large pools.  This helps keep equipment wear to the minimum as all heat pumps will be operating in concert during a demand cycle.

In Conclusion

While pool heating can be daunting at first glance, they are relatively simple machines that are usually easy to service with some prior exposure.  The basic refrigeration principles all remain the same.  The next time a customer asks you why their pool is cold, don’t shy away from getting some hands-on experience.  You may find a niché at your company!

— Zach

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 that coil and performed a definitive test to locate it in the video below.

A leak detector can be tricky to use so here are some of our top tips –

  • Know your detector. Know it’s limitations, it’s sensitivity and what can cause false positives. For example some leak detectors will sound off on certain cleaners or even soap bubbles. My detector sounds off when jostled or when the tip is blocked.
  • Keep a reference bottle so you can check your detector every time before you use it.
  • Maintain your detector and replace the sensor as required. Most heated diode detectors require sensor replacement every 100 hrs or so.
  • Keep it out of moisture. Most detectors will be damaged by almost any amount of moisture.
  • Move slowly and steadily. Don’t jump around or get impatient.
  • Most refrigerant is heavier than air which means that starting from the top and working down is usually a more effective way to pinpoint.
  • Go back to the same point again and again to confirm a leak. Don’t condemn a component bases on one “hit”
  • Find the leak WITH BUBBLES whenever remotely possible, even after pinpointing with a detector.

— Bryan

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 me thinking….

I don’t want to be an A/C god, too much pressure, and heaven knows I’ve broken all of these rules more than once. I’ll settle with being an A/C Moses, descending Mount Sinai with the oracles of truth from on high

The problems with this metaphor are many, but let’s roll with it. The truth is there are many “prophets” like Jim Bergmann, Dave Boyd, Dan Holohan, Jack Rise, John Tomczyk, Bill Johnson, Dick Wirz and Carter Stanfield that I have taken these “commands” from and they likely learned these from those that came before them. Just DON’T build a golden calf to poor workmanship or we will smash the tablets and make a big mess… Ok here are the commands.

1. Thou Shalt Diagnose Completely

Don’t stop at the first diagnosis. Check everything in the system, visually first if possible, and then verify with measurements. Sometimes one repair must be made before other tests can be done, but often you can find the cause of the initial problem as well as other problems BEFORE making a repair which helps save time, provides better customer service, and creates a better result.

2. Thou Shalt not Make Unto Thee Thine Own Reasons

Jim Bergmann often talks about how when techs don’t understand something, they start making up their own reasons that something is occurring, and then train other techs in these made up reasons. If you don’t understand something, a bit of research and study goes a long way.

3. Thou Shalt Not Change Parts in Vain

In other words, DON’T BE A PARTS CHANGER. Never condemn a part on a guess or make a diagnosis out of frustration. Get to the bottom of the issue no matter how long it takes. This is better for the customer, the company, the manufacturer, and your development as a tech. If you aren’t confident, call someone who is fundamentally sound and get a second opinion BEFORE you leave the site. Better yet, send them a text with all the readings, model and serials, conditions, photos, type of compressor, type of controls, type of metering device, and what you have done BEFORE you call them. Get the diagnosis right the first time.

4. Remember the Airflow and Keep it Wholly

So much of HVAC/R system operation has to do with evaporator load with LOW load being most commonly caused by LOW AIRFLOW and low air flow being most commonly caused by dirt buildup. Keep blowers, fans, filters and coils clean and unobstructed. Check static pressure when duct issues are suspected in order to verify and properly setup blower CFM output to match the requirements of the space and outdoor environment.

5. Honor Thy Trainers and Mentors

New techs will often learn a few facts and cling to them as though they are the end all and be all of system diagnosis. I have met techs who get over focused on everything from suction pressure (most common), to superheat, subcool, static pressure, delta T, and amp draw. A good tech continues learning from older and wiser techs and trainers who see the whole picture. When you are new it’s hard to remember all of the factors that go into system diagnosis and performance. More experienced techs who have kept up on their learning develop a “6th sense” that can rub off on you if you “Stay Humble” (to quote the great philosopher Kendrick Lamar). Listen more than you talk, and learn the full range of diagnostic and mechanical skills.

6. Thou Shalt Not Murder The System by Failing to Clean

A good technician learns the importance of keeping a system clean early on and never forgets it. Condenser coils, base pans, drain pans, drains, evaporators, blower wheels, filters, return grilles, secondary heat exchangers and on and on… A system that is set up properly initially and cleaned regularly will last much longer, cool or heat better, and use less energy. In my experience, techs that don’t believe in maintenance don’t perform a proper maintenance themselves. Use your eyes, and clean what’s dirty.

7. Thou Shalt Not Commit Purgery without Vacuumy

Proper evacuation is one of the most overlooked disciplines of the trade. Dave Boyd and Jim Bergmann say again and again, a proper vacuum is performed with large diameter hoses connected to core removal tools. The cores are removed from the ports, the hoses have no core depressors, the hoses are connected directly to the pump (not through gauges). The vacuum (micron) gauge is connected on the side port of the core removal tool, not at the pump. The pump has clean vacuum pump oil and the pump is run until the system is pulled below 500 microns (exact depth depends on the system). The core tools are then valved off and the “decay” is monitored to ensure that the system is clean and tight.

Purging with dry nitrogen prior to deep vacuum helps with the speed of evacuation, and installing line driers assist in keeping the system clean and dry, but neither are a substitute for a proper deep vacuum and decay test.

8. Thou Shalt Not Steal (from the customer)

Good techs provide solutions for their customers to get a broken system working, as well as other repairs or upgrades that result in optimum performance. Most techs don’t INTEND to lie to a customer, but their lack of understanding on the products they are OFFERING, along with strong incentives to OFFER these upgrades can result in dishonest practices. A good, profitable technician has a deep understanding of all the repairs and upgrades they perform, as well as a sense of empathy for the customer.

9. Thou Shalt Not Bear False Witness Against Other Technicians

This all comes down to a witch’s brew of ego and insecurity all mixed together. You have either done this yourself, or you know of someone who has gone to a customer’s home or business and thrown the previous technician or company under the bus in front of the customer. In some cases it may be nothing but bravado, and in other cases it may have a measure of truth in it (or may be undisputed). Either way, talking negatively about other techs and companies does nothing but make you look petty and angry. Demonstrate your skill and knowledge by discussing the courses of action you intend to take, and if required, you can COMPARE these actions to previous actions taken; just stay away from personal attacks. Let the customer be the judge about the last guy.

10. Thou Shalt not Covet Thy Neighbor’s Job

Many good techs start to do poor quality work when they get burned out… and buddy let me tell you- I HAVE BEEN THERE. It is important to remember that every job from maintenance tech to business owner has good things and bad things about it. There are good days and bad days, great customers and total jerks, 16 hr days and 8 hr days. You may hit a spot where you decide to change jobs, and that is totally fine and may be a great decision. Just don’t make a rash decision because the grass looks a little greener. ALWAYS do quality work no matter where you work, or how bad it gets. Doing poor quality work because your job is getting you down is like a cancer that will grow and do harm to you and your career.

Take pride in your work, keep your eyes and ears open, learn something new every day and the HVAC/R gods will smile warmly upon you.

 What commands would you add or remove?

— Bryan

 

 


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 does not mean it actually produces 36,000 btu/hr even during RATED conditions let alone real world conditions.

Some of you may be used to pulling up an AHRI rating to find the true capacity of a system match. This is a good start and often you will find out that the the system produces slightly less to up 4,000 btu/hr less than the nominal rating. Here is the AHRI ratings for the system I have on my home.

You will notice that the 2-ton matches actually produces 24,000 btu/hr at the rated conditions, which are REALLY WARM temps inside and out by the way. However the 4-ton match produces 46,000 btu/hr at the same conditions.

Here is an example of some real world capacity readings I took on my Carrier VNA8 4-ton system with the Testo Smart Probes app and two 605i thermo-hygrometers.


This is a 4 ton unit with a proper charge (right at 11.6 subcool like the Infinity stat calls for) a 0.45 TESP and it’s been running for 30 minutes at high stage. You might be tempted to think something is wrong with the measurement or the unit, but we need to look closer.


You will notice pretty quick that my indoor temperature is low (68.3db)with a low indoor RH (54%) which equates to a 57 degree wet bulb indoor return.

Also, the outdoor temperature is only 72 degrees DB. In order to tell if 41,000 btu/hr is within range or not we will need to look in detail at the manufacturers expanded performance data located in the product data.

Here is the expanded data for this particular match and we lucked out. My air handler, condenser and suction line size are the match that the rating is based on. In some cases you will need to use a multiplier based on an alternate match or smaller copper sizes which can further reduce the rated capacity and possibly the efficiency as well like in the case of the FE4ANF003 or 002 below.

Now let’s zoom in on the performance data that applies to our actual conditions and see how we did.

The highlighted figure is the closest this chart comes to our actual conditions, though our indoor dry bulb is actually significantly lower than the 75 degree DB on the chart. So now the real world 41,223 btu/hr actually stacks up pretty well with the 42,870 btu/hr on the chart.

All of this to say that when sizing equipment and when testing capacity there is a LOT more to it than just the nominal tonnage in the model #. The only real way to know is to dig into the manufacturer product data and really understand that piece of equipment of equipment.

— Bryan

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