Tag: hvac

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 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 set pressure. However, there are other applications for which liquid line solenoid valves are useful. Long line applications in HVAC incur a wide range of challenges a technician must evaluate. Among those challenges include oil return, refrigerant migration in off-cycle, compressor workload, efficiency and capacity losses, added refrigerant charge, and metering device selection.

Long line applications (for R410a straight AC and Heat Pumps with ⅜” liquid lines) are generally defined as any system with a line set longer than 80 ft in equivalent length. Equivalent length in this context means that all pressure drops (copper fittings, bends, diameter size changes) translate to a length equivalent to a run of straight copper. Manufacturer spec data for copper fittings will have printed the equivalent length of those fittings in its literature. The length to be exceeded before long line application procedures are used may vary depending on line set diameter size and on which plane the indoor and outdoor units are located, but 80 ft is the general rule for Residential AC and HPs. Any system with a 20 ft uninterrupted vertical rise in the line set should also be treated as a long line application, per Carrier’s Long Line Application Guideline, which will be linked here.


There are many ways manufacturers have sought to resolve the challenges with long line applications. Some of these solutions include crankcase heaters and txv metering devices. Most manufacturers will specify an OEM hard-start kit for the purposes of protecting compressor effectiveness against the added refrigerant charge. Some commercial applications require oil traps to aid in oil return. 


Liquid line solenoid valves are specifically utilized to prevent refrigerant migration in the off-cycle. The valve is positioned with the arrow printed on the valve body pointing toward the outdoor unit. For heat pumps, the valve must be biflow. It is important to note that the valve is normally closed in these long line applications. When energized with the contactor of the outdoor unit, the coil in the valve body will pull the valve open to allow flow. However, when closed, the valve only stops refrigerant from flowing in the direction of the arrow printed on the valve. With the system in the off-cycle, the solenoid valve will keep refrigerant liquid and vapor from migrating to the compressor down the liquid line. But don’t let the refrigerant tubing size fool you! Just because the liquid line is 3/8″ doesn’t mean any liquid line solenoid valve with 3/8″ sweat or flare connections will do. Care must be taken when selecting a solenoid valve. Choose valves to match the capacity of the system on which it will be installed (with a pressure drop of no more than 1 psi), then pay attention to refrigerant rating, THEN select by line set diameter size. 


Wiring a liquid line solenoid valve will generally tap in with the thermostat’s call for the compressor. The valve should be wired into the Y (outdoor unit contactor) and C (common) terminals on single-stage equipment. For two-stage equipment, make sure the valve opens with a call for the first stage of heating or cooling (Y1). This prevents the valve from remaining closed during compressor operation.

Solenoid valves are incredibly simple in design and operation, and troubleshooting for long line applications is also quite simple. Confirm the coil is receiving its rated applied voltage when the system is energized, and test temperature drop across the valve. A maximum of 3° difference is allowable. The valves are NC (normally closed), so if there is a temp drop across the valve body, but no applied voltage during system operation, confirm your wiring. 


Always make sure you are applying industry best practices when installing a solenoid valve. Remove the coil from the valve body before installation to prevent overheating. Use a heat absorption putty, spray, or wet rag on the valve body. Flow nitrogen while brazing, and install filter driers everytime (oversized if possible).


Long-line applications are few and far between in residential HVAC. But if you ever encounter a situation where you see a liquid line solenoid valve next to the outdoor unit, pay close attention to the way that system is setup and any other added accessories that may have been installed. You may refer to the Residential Long-Line Application Guideline at any time.


-Kaleb Saleeby


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 a snob.

It’s embarrassing to admit because I never wanted to be a snob. I’ve consistently railed against snobbery whenever I bumped up against it.

But now I am one.

My snobbishness has been YEARS in the making.

I remember being on call when I was 20 years old and hearing my emergency pager going off at 1 am. At that time we had a toddler who wasn’t the best sleeper and we were living in a one-room “house”. I rolled out of bed and walked outside to call the customer, speaking out loud beforehand to try and get the sleep out of my voice before I dialed.

Me: “Hello, may I speak with Mr. Pedergast?”
Customer: “Yes, Who is this!”
Me: “This is the A/C technician with (redacted), I received a call that you have an emergency?”
Customer: “Yeah, you guys were JUST out here and now my A/C isn’t working and I need you out here right away!”
Me: “Ok, I will be out within a few hours, please have any recent invoices available so I can take a look before I start working”
Customer: “What! TWO HOURS! You won’t be here until 3 am? I need to WORK in the morning”
Me: “I will be there as soon as I can sir, It would be two hours at most”
Customer: “OK, just get here as soon as you can… (click)”

Needless to say, Mr. Pendergast actually had 3 systems in his home but the one that wasn’t working was his master bedroom so it was an absolute emergency, heaven forbid he use the spare room or **gasp** SLEEP ON THE SOFA.

It also turns out we hadn’t worked on THAT system recently, we had worked on another one but that didn’t prevent him from pitching a fit when I wrote down a diagnosis fee on the invoice.

So I have a question directed at the mindset that drives people like this customer to devalue the trades and the people who work in them. What can you ACTUALLY DO Mr. Pendergast? What real value to YOU add to society? Who needs YOU at 2 am? What does YOUR work day look like? How many real-world problems do YOU solve?

I have these thoughts now that I didn’t necessarily have when I was 20, because at that time I may have had much the same view of my work and value that Mr. Pendergast had. Back then I wasn’t a snob that looked down on people like Mr. Pendergast, now I am, much to my own chagrin.

What does this have to do with the skills gap? 

This customer is an extreme version of a larger challenge that exists in the minds of people from CEOs to Tradespeople themselves. This is the belief that one type of work is “more important” than another and therefore doing one thing over another makes you (or others) more or less important.

As I’ve progressed in my career and interacted with more people from various “prestigious” professions I’ve noticed three things that relate to this topic.

  1. Many of them are excellent people that I enjoy immensely
  2. They have no idea what it takes to do what we do
  3. They aren’t any better, smarter or more important than tradespeople

You see, most of them don’t really think they are BETTER than you and I, they just don’t have clue what it means to BE you and I. They can imagine what it’s like to work in an attic or crawlspace, to drag a gas furnace through the dirt, up a hill with a hand truck or to work on call into the wee hours of the morning but they still have NO CLUE what it really takes.

And that’s OK! it isn’t their experience so they can’t be expected to understand. You cannot change how others see the world by complaining about their worldview. We can change it by taking steps to value the trade ourselves and start thinking about all work, education and recruiting a bit differently.

Manifesto for Filling the Skills Gap 

#1 – The Trades Don’t Always Need to be a Full Contact Sport

I hear it all the time, some version of “I don’t want to be turning a wrench when I’m 60, my body can’t handle it!”.

That would be like asking a running back to carry the ball in the NFL or a pitcher still throwing it 96 MPH when they’re 60. There are aspects of our trade that are very physically demanding, there are segments that are minimally demanding and then there are roles that will allow you to sit in front of a screen and talk on a phone most of the time.

I wrote that last one because I knew 99% of you who have worked in the field got hives just THINKING about sitting in front of a computer all day. Many of us work with our hands because we ENJOY working with our hands, getting some fresh air, turning a wrench now and then and ultimately solving problems in the real world.

Which of us as little kids dreamed of a future where we would sit behind a desk answering emails and attending meetings all day?

We all have a desire to DO COOL THINGS not just talk about cool things and certainly not to sit on our butts staring at a screen all day.

The real problem isn’t turning a wrench, the issue is that we are afraid that the trade will use up our bodies and then leave us hanging when we can no longer throw the ball 96 MPH.

Here’s the truth, nobody who continues to invest in their mind and personal growth will be left hanging by this trade moving forward. There is just too much to do and too few people to do it. Getting left behind will happen due to lack of development and preparation not because of something intrinsic to the trade.

We have never needed the minds of those who have been around the business for 30+ years more than we do today. There just needs to be a shift in thinking from working our whole careers with the exact same focus to shifting from mostly physical to mostly mental work as we mature, I call this shifting from blue-collar to new-collar. This shift from physical to mostly mental takes time and intentionality but it’s critical to the future of the trade.

If we begin to phase more experienced people into training and supervision earlier it will keep more people in the trade and help improve the next crop, but there is a catch… The grouchy, inflexible, ego-driven, foul-mouthed tech won’t fit into these roles and will be left behind because they cannot be trusted to supervise and train.

Here is the litmus test for whether you are ready to begin making the transition. If you have been in the trade for 15+ years go ahead and think about a new technology that’s come out in the last 5 years that you are really comfortable with. Now think about your three favorite books, audio-books or podcasts on personal development or leadership. If you are drawing a blank then that is where you start.

We must have intentional programs and processes to transition more experienced workers to roles that utilize their field knowledge while coaching them on educational and leadership skills and traits. We need to leverage technology and resources to train and develop skills into existing tradespeople before looking forward to the next generation.

#2 – The Education System is Broken 

There are many incredible educators, schools and resources. Learning isn’t broken, the education SYSTEM is broken, especially for the trades.

“I have never let my schooling interfere with my education” ~ Mark Twain

Humans learn through concept association (how this works reminds me of how that works) and practice. Yet the education system tries to teach using disassociated facts and memorization.

Imagine the US education system trying to teach a baby how to speak. They would develop a 4-year program where the baby would be taught Latin and Greek word roots, the history and science of words and then given speaking tests to see what they remembered.

How do babies actually learn to speak? They learn by hearing language used constantly and once they learn some words they make inferences on the meanings and pronunciations of other words which they then practice in context. Once the baby starts speaking then other adults and children begin to provide them with feedback on ways to improve their vocabulary and pronunciation.

Learning  is natural and organic and it has three necessary components

  1. Desire to Learn
  2. Observation & Practice in Context
  3. Feedback & Instruction in Context

The education system can only provide #3 and it can only be expected to do it well when the first two elements are in place. Many of us grew up watching adults do things around the house like installing an outlet, changing a tire or soaking a mower carburetor. Once we started in a trade school or in the field we already had a “language” of tactile skills we could draw from when we saw things in our trade of choice. If we had a good instructor or worked with a good journeyman they would draw on the language and mechanical concepts we already understood to relate concepts in HVAC/R. This is why many of us learned electrical theory as related to the flow of water in pipes, we had already seen water flow so this would help us understand the movement of electricity.

Many young people entering the workplace today don’t speak the same mechanical language we spoke as kids because their experiences are more likely to be of screens and computer keyboards than fire, gasoline, and plumbing.

With this being what it is we need to give new students and apprentices more experiences with the basics of mechanical assembly and tools before we can expect them to understand mechanical concepts taught in a lecture.

This is not only true of the trades, this is also why many young people don’t have basic skills like balancing a bank account, doing laundry or dealing with disappointment. You don’t learn these skills in a class, you learn them by doing them and dealing with them and often the culture emphasizes skills that are far less necessary for life than these. To bring it to a point, we think you need to learn theory and facts and then gain practice when really you must have a constant cycle between facts and application for it to make any sense. Often this means seeing something done and doing it before you can learn why you did it or why it matters.

We must develop programs that allow for a continuous loop of observation, practice, instruction, and feedback that focuses on the application of a skill more than the information. Effective education develops the tactile “language” of learning rather than just hammering away at the information. We cannot wait for government programs to do this for us. Contractors, OEMs, wholesalers, educators, influencers and reps need to work together to make this a reality.

#3 – Change Starts Between Our Ears

Back to me being a snob.

I don’t know what Mr. Pendergast did for a living, maybe he was a scientist working on a cure for cancer or an astronaut or a recently deposed dictator (which I imagine to be most likely). I can tell you that I’m glad that I work in a job where what I do makes a difference in peoples lives. I’m glad for an honest days work, doing pretty awesome stuff with some pretty neat tools, working alongside some really smart people. I’m glad I don’t devalue the hard work of others and their sacrifice like Mr. Pendergast did with me.

I spoke on a panel the other day where the question came up about recruiting the next generation and why young people don’t flock to the trades. I asked for a show of hands from the audience of how many of them encourage their kids to enter the trades. Only a few hands went up out of hundreds of people.

Maybe the reason we have a problem getting young people into the trades is because parents encourage kids to go into a career where they don’t need to put in a hard physical days work.

Why is that?

Do we think there is something wrong with having dirty hands and lifting heavy things every once and a while? I don’t think that’s it based on how many people pay GOOD MONEY to attend CrossFit classes and mud runs.

I think much of society has bought into a lie that working in blue collar jobs is somehow a “lesser” option. You are OK with your kids working an apprenticeship and attending a trade school if “college isn’t for them” or if they “Just aren’t academic” but not as a first option.

Those of you pushing your kids towards college, how would you feel if I said “Yeah I understand, some kids just aren’t suited to work for a living”. It’s insulting and ridiculous to assume that a kid needs to choose a trade if “college just isn’t for them”. Maybe they should choose a trade because it’s an interesting, rewarding and tactile career path where you get to solve real problems every day.

Ultimately I want my kids to do whatever they do with excellence and I want them to enjoy the path they choose whether that is as an HVAC tech or a physicist, although I’m pretty biased to HVAC myself.

We need to ask ourselves if we are ashamed of being in a blue-collar industry and if that impacts how we talk about our work to young people. If we are excited about this trade then don’t be afraid to be outspoken about it. 

Let’s get the skills gap filled by creating better paths for experienced people, improving education and being really excited about the opportunities in our trade for the next generation.

Oh and that toddler who my pager almost woke up… he just started as an apprentice in the trade. Don’t worry, he can always go to college as a plan B if he can’t cut it 😉

— The HVAC Snob – Bryan Orr

And no… his real name wasn’t Mr. Pendergast. That name is taken from a grouchy guy in one of my favorite movies as a kid. Do you know which one?


Capacitors are traditionally tested with a capacitance meter (commonly found as a function within a multi-meter) with the component taken completely out of the circuit. “Bench testing”, as this method is referred to, is hands down the safest method of checking capacitance in micro-farads. All other methods require the capacitor to be wired into the circuit with an applied load. To bench test, you simply take the meter leads and check across the terminals of the capacitor. For a dual-run capacitor, you would check between the Common terminal and whichever side (Fan or Herm) you wished to test.

Another popular test many technicians use is the “Under Load Capacitance Calculation”. This test is performed while the system is in normal operation. A technician would measure voltage across the terminals of the capacitor (again, Common and Motor terminals if dual-run), then current off the start winding of the motor to which the capacitor is attached. Next, you plug those values into a calculation, which uses a mathematical constant: (amps x 2,652) ÷ voltage. Finally, the product of that calculation is compared against the rated capacitance printed on the capacitor. As long as the calculated value is within +/- 6% of the rated value, the capacitor quality is acceptable.

Bench testing and capacitance calculations are pretty popular choices when verifying the capacitance of a capacitor against its rating. However, there is yet another way to test a capacitor under load you may not have thought of before. You can use a power quality meter to check the capacitor under load using power factor. In order to explain the validity of this measurement, here is a review of reactive power, inductive loads, and capacitors.

Reactive power is one of three different types of power in an alternating current circuit. True Power is the actual energy in watts dissipated by a circuit. In other words, the real work being done. Then there is Apparent Power, measured in Volts-Amps (VA). Apparent power is the RMS current multiplied by the RMS voltage. Reactive Power is the power dissipated as a result of either inductive or capacitive loads. Reactive Power is measured in Volts-Amps Reactive (VAr). When the current and voltage waveforms are out of phase with each other, that is reactive power.  Inductive loads, such as a condenser fan motor, are inductive by virtue of the fact their alternating current lags behind the alternating voltage as the current flows into the load. Capacitive loads have an alternating current waveform that leads the alternating waveform of the voltage.

For the purposes of this tech tip, inductive loads will be exclusively discussed, because they are most common in the residential field; i.e. condenser, blower, and compressor motors. Inductive loads use a magnetic field to cause physical movement. The magnetic field is generated as electric current flows through a coil. In other words, this current/energy used to generate a magnetic field is known as reactive power. Notice, however, there is no real work being done. The force of the magnetic field can cause physical movement (work), but it does no real work itself. Inductive loads need reactive power in order to do work, but by using more and more reactive power, the load uses also uses more current (usually from the utility company). Take a look at the “Power Triangle”. Pictured is a power triangle depicting an inductive load. The hypotenuse of this triangle is notated as Apparent Power (the available power in the circuit). The leg on the y-axis is notated as Reactive Power (magnetic field), and the leg on the x-axis is notated as Real Power (actual work being done). If you notice the Theta symbol in the left acute hypotenuse angle (𝜭), this is referring to the Power factor of the load. Power factor (cos𝜭) is the ratio of the average Real Power in watts to the Apparent Power in volts-amps . Ideally, the Apparent and Real Power would be the same, as in a Resistive load (i.e. a power factor of 1). However, inductive loads need a magnetic field.

If the reactive power leg on the y-axis were to increase and rise higher on the y-axis, the hypotenuse (apparent power) would also increase. The power factor, in this case, decreases, and moves closer and closer to the left acute hypotenuse angle, thereby increasing the distance between the Apparent power and Real power. This is counter-productive, because as the load uses more current, more heat energy is generated, and the energy used to do the actual work becomes inefficient.

Therefore, the goal of the engineer is to minimize the amount of reactive power the inductive load uses from the apparent power. Basically, the goal is to increase power factor back to as close to unity (1) as possible. This is when capacitors enter the scene.

Capacitors are generally accepted as reactive power generators. To understand more about how capacitors work, and some common misconceptions, check out these other tech tips/podcast episodes: Run Capacitor Facts You May Not Know (Podcast) 5 Capacitor Facts You Should Know

Capacitors, when applied to a circuit, decrease the amount of apparent power needed by the inductive load to generate the magnetic field. This effectively increases the power factor. Looking at the power triangle again, as the Reactive power on the y axis decreases, the hypotenuse (Apparent power) also decreases, moving closer to the Real power. This is the endgame for capacitors.

Therefore, it can be inferred from the understanding of inductive loads and capacitors: if a capacitor is attached to an AC circuit in an inductive load (like a PSC motor) for the purpose of bringing power factor back to as close to unity as possible, but the power factor is measured to be low, the capacitor must then be either sized incorrectly or failing/failed.

Using a power quality meter on an inductive load, a technician can judge the functionality of a particular capacitor. To do this, Voltage and Current must be measured simultaneously at the load. The Supco Redfish iDVM-550 is a great tool for this application.

It must be mentioned that using a power quality meter to measure power factor on a load is valid only when the load contains run capacitors like compressors and permanent-split capacitor motors. ECMs (electronically commutated motors) use a different type of technology altogether, and they are engineered for use with a lower power factor by design. Also, power factor testing is not practical for start capacitors either, since the capacitor is taken out of the circuit too quickly. This measurement is valid and practical only for PSC type blower, condenser motors, and most single-phase, single-stage compressors. 

As the evening approaches on this All Hallow’s Eve, Reformation day or Halloween (depending on your preference), let us take a moment to focus on some of the truly terrifying elements of our trade, because the Scariest stories are TRUE.

Real Ghost Stories 

The year was 1921 and a wealthy family purchased a new home in quiet part of town. It was a large, old building and the family was excited to live in such a majestic home.

The trouble started almost right away and the lady of the home (referred to only as Mrs. H) began to recount her experiences in the home to her doctor in letters that were later published.

This house was lit by gaslights and had servants quarters and passageways, a perfect house for a haunting. From Mrs. H’s account to her doctor:

“One morning, I heard footsteps in the room over my head. I hurried up the stairs. To my surprise, the room was empty. I passed into the next and then into all the rooms on that floor, and then to the floor above to find that I was the only person in that part of the house. Sometimes after I’ve gone to bed, the noises from the store room are tremendous, as if furniture was being piled against the door, as if china was being moved about, and occasionally a long and fearful sigh or wail.

“Sometimes as I walk along the hall, I feel as if someone was following me, going to touch me. You cannot understand it if you’ve not experienced it. But it’s real. As I was dressing for breakfast one morning, B, who is four years old, came to my room and asked me why I’d called him. I told him I’d not called him, that I’d not been in his room. With big and startled eyes he said, ‘Who was it, then, that called me? Who made that pounding noise?’

“I told him it was undoubtedly the wind rattling his window. ‘No,’ he said, ‘It was not that. It was somebody that called me. Who was it?’ And so on he talked, insisting that he’d been called and for me to explain who it had been.”

The hallucinations continued, with the family feeling the presence of the unknown. They experience hauntings, rattling beds, lethargy, and temporary paralysis. Even the plants began to wither and die.

Mrs. H continues:

“Some nights, after I’ve been in bed for a while, I’ve felt as if the bed clothes were jerked off me. And I’ve also felt as if I’d been struck on the shoulder. One night I woke up and saw, sitting on the foot of my bed, a man and a woman. The woman was young, dark and slight and wore a large picture hat. I was paralyzed and could not move.”

After speaking with different people about their malady with the spirit realm, a relative suggested that they are being poisoned. He had heard similar accounts from people poisoned by combustion gases experiencing similar symptoms.

It turned out that the gas lighting and the furnace were dumping carbon monoxide in the home. As soon as the furnace was properly vented their ghosts disappeared and life returned to normal.

This preceding story is one of my favorites from the Podcast and Radio Show This American Life which was brought to their attention by Albert Donnay, toxicologist and CO expert.

It makes me wonder how many of the hauntings in these old homes is due to CO rather than the spirit realm.

The Deadly Gift 

The year was 1938 and Walt Disney was just off of his first blockbuster success with his film “Snow White”.

Walt and his brother Roy decided to buy a new home for their parents in North Hollywood, finally moving them down from Oregon to be near their now famous sons. In November of 1938 their mother complained to Walt that the furnace smelled strange so he sent some of his studio repairmen over to have a look.

Several days later the housekeeper found both of Disney’s parents unconscious in the home, with their mother Flora dying shortly after. Their father recovered shortly after, but many accounts say that Walt never forgave himself and was later heard mumbling

“I told those techs to buy a BluFlame combustion analyzer from TruTech tools before they went out. Heaven knows if they used the coupon code getschooled they would have had significant savings!”

All of my facts in that story are definitely, 100%,  maybe true.

In all seriousness, testing combustion and using low level CO monitors in homes and for yourself while working around combustion appliances can save many lives as well as undiagnosed illness and even a haunting now and then. See anything wrong with the furnace above?

Roofs and Ladders 

We were called out to a new high rise condo building in our area to maintain a bunch of rooftop equipment and what we found was an acrophobic nightmare. No guard rails, no parapet wall… just equipment, with much of it a few feet from the edge with sure death awaiting below.

Our service manager promptly called the customer and let them know that we would be back once they had measures in place to make the equipment safe to service.

Guess what they responded?

Nobody else has a problem with it

Whether it’s equipment that cannot be safely serviced according to OSHA 1910.1 like the ones above or extension ladders put up through scuttle holes 20′ straight up we need to start making customers responsible for providing us with safe working conditions rather than just doing it because “Nobody else complained”.

Maybe a harness tied off can work the first time until they get a proper permanent ladder or guardrail or WHATEVER WORKS, but just going back time and time again and putting ourselves in danger is the definition of insanity.

Moisture Problems 

The pager went off at 2 AM… I was on call AGAIN because the guy who WAS on call quit right in the middle of his week… he just couldn’t take this thing beeping at all hours. I grabbed the on call cell phone that was as long as your forearm and dialed the after hours voicemail line… YOU HAVE ONE NEW MESSAGE… the familiar robotic voice chirped at me.

The man in the recording sounded panicked “You were all out here earlier today and replaced an evaporator coil and now my WHOLE CEILING JUST FELL IN!”

Well… It wasn’t his ENTIRE ceiling, just a large portion of his master closet ceiling over his suits and ties and patent leather shoes. All of this happened because the tech out earlier that day hadn’t paid attention to how he strapped drain and there was a newly formed sag resulting in a double trap. Add in the fact that he had “moved” the pan switch out of the way and forgot to reinstall it properly.

Water damage, mold and mildew, lawsuits and 2 AM service calls can be prevented by paying attention to –

  • Drain pitch
  • Float Switch Location and Testing
  • Drain Cleaning
  • Pan Positioning
  • Proper configuration of drains in horizontal applications
  • Drain Cleaning

Many of the biggest nightmares in my career have been due to drain issues and moisture due to surfaces hitting dew-point. Keep the moisture where it belongs and the pager will stay quiet… who has pagers anymore anyway?

The Tiny Plug

I was sitting on the couch the other evening watching football when my oldest son who rarely has much to say piped up and said

“Dad, what happens if you test gas pressure and forget to put the plug back in”

The hair raised on parts of me where hair shouldn’t raise.

Turns out he was just curious and hadn’t actually forgotten to put the test plug back in on a valve but it did get me thinking that there is nothing quite so scary in our trade as a combustible gas leak and none more odious than “forgetting” something that critical.

When working on gas appliances always make sure to leak check connections and for gas bypassing the valve during the off cycle using a combustible gas leak detector…. Trust your nose as well… if you smell gas odorants then investigate.

Most of all…


Whatever you do…

Don’t forget to put the little plug back in after testing the gas pressure.

Also watch out for razor blades in your apples tonight… or better yet… don’t eat fruit being handed out during Halloween. What sort of demented psychopath hands out fruit on Halloween?

— 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 airflow 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. Jim Bergmann says 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 assists 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



Before we jump into the stuff that will make folks angry, let’s start with some common ground.

Can we 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 we all have this common goal in mind, can we also agree that any way we can achieve this result in a faster, broader and more effective way would be a good thing?


Now what follows is admittedly one perspective on how we can better achieve these outcomes. This isn’t scientifically quantified, it certainly contains some confirmation bias, but I can state with all honesty that it comes from a desire to help the trades achieve these goals.


10 years ago when techs first started putting HVAC/R videos on YouTube there was a huge backlash. For any of you that were on HVAC-Talk back then, you remember all of the doom and gloom.

Homeowners were going to use the info and kill themselves, bad practices were going to take over the trades, guys were going to go to “YouTube University” and think they know it all.

A decade has passed and those prophecies just haven’t come to pass at any significant scale.

The reason for this (in my mind) is the people who actively seek answers to questions are far better off than those who simply swallow what they are told by their teacher or the old timer who trained them.

Out in the light of day ideas have a chance to either thrive or die on their own merit rather than festering in the cold damp corners of “that’s the way I was taught” or “it always worked for me”.

Sure… there have been some bad actors teaching some silly and dangerous stuff along the way, but there have also been some excellent resources that have started discussions and brought ideas to the forefront that could have NEVER spread so quickly without the free sharing of ideas.

“I have never let my schooling interfere with my education” ~ Mark Twain

Guess where some of the bad ideas that have persisted for generations came from before the YouTube and social media era?

In my experience, it was bad teachers and bad “senior” techs sharing poorly formulated ideas under the protection of intellectual isolation.

In other words, bad ideas formed and grew due to lack of scrutiny, or “peer review” if you prefer an academic term.

What are the gates and who are the Gatekeepers? 

They can be trade schools, manufacturers, traditional book publishers, universities, governing bodies, regulators, educators and the list goes on and on…

Anyone who intentionally places barriers in front of education is part of the problem in my worldview.

What I’m NOT saying –

  • Education should all be free
  • Formal education is worthless
  • The system is the problem
  • Poorly prepared workers should be thrown into the workplace

What I AM saying

  • Learning and progress should be heralded over certifications and degrees
  • What you know and can do is more important than how long you’ve been doing it
  • A lot of time and effort is wasted in bureaucracy and red tape rather than actually reinforcing learning and a passion for learning
  • Self-education is a lifelong skill that should be fostered at every opportunity

“Education is the kindling of a flame, not the filling of a vessel.” – Socrates

Self Education is Worth Promoting

Whether or not you are formally educated, self-education is paramount to success.

About a year ago I received an application for a service tech apprentice position with the following listed under the previous education field.

Self Study: EPA 608, R-410a Certification, PM Tech Certification, Refrigeration, and Air Conditioning Technology, Commercial Refrigeration: For Air Conditioning Technicians, Blue Collar Roots Network podcasts

When he came in for an interview he was polite and quiet, I asked him how he got the certifications if he didn’t go to a formal trade school, he replied: “I just found where I had to go and went out and got them”.

Do you think he ended up working out well? OF COURSE, HE DID!

He’s a self-starter, he doesn’t need a gatekeeper to tell him when or how to learn something he just went out and learned until he understood.

Does that mean we threw him in a truck right away? NO WAY! You can’t learn to ride a bike at a seminar and you can’t teach someone how to be an HVAC/R tech with a book, podcast or video.

He had to practice and apply what he had learned before the learning could manifest itself into skills but he came to the table with the proper mindset which led to the inevitable result of skill and mastery.

The “CYA” or Lawyer excuse

I sent out an email not long ago to a well known OEM seeking approval to use small portions of their bulletin content (with attribution) for some tech tips. Last I heard their lawyers were looking into it.

We get this a lot in the education side of the trade, a fear of “plagurizing” or saying the wrong thing so someone gets sued and then out of the OTHER side of their mouths comes complaints about the “skills gap” and difficulties in education.

I have a piece of advice on the lawyer and copyright stuff surrounding trade education…


Obviously, if someone is directly copying or republishing your content as their own then that’s a problem and needs to be dealt with. Other than that, WHAT IS THE PROBLEM!

If people are sharing excerpts from your manual or book or bulletin online, do you REALLY think that’s a risk to your brand or business?

Do you honestly believe that people who are excited enough about the trade to share or excerpt from something you made are a problem?

Are you HONESTLY concerned that overeducation of the general consumer is a valid problem to protect against in comparison with the growing skills gap in our trade?

Do you think that good quality traditional HVAC/R education is at risk of being replaced by people online sharing good training materials?

“Risk comes from not knowing what you’re doing” ~ Warren Buffet

Risk Aversion

I have 10 kids and only one broken bone among them over 17 years (by the grace of God).

My kids hang from trees, ride bikes around the yard and on the driveway (with no helmet at times), ride our gas powered golf cart (too fast at times) and work with tools on all sorts of things. They cut veggies with knives for dinner, climb ladders to the attic, walk on trusses (the older ones) and ride skateboards with no kneepads.

Does this upbringing sound familiar to you? It probably does because that is the way that many of us were raised and it was certainly the way the generation that went to the moon strapped to a rocket were raised.

The point is that we all learn how to do fairly risky things SAFELY by being allowed to do them in reasonable low risk environments.

But HEAVEN FORBID we allow a 16 year old to job shadow or climb a ladder or use a saw.

How did we get to be so risk averse, especially in a trade where we melt metal with fire, run explosive gasses into buildings and set it on fire, freeze things and make sparks regularly.

If we didn’t want to take risks we should have become a hotel concierge, not an HVAC/R professional.

Now there is no reason to be foolish and we should look for ways to do things as safely as practically possible… but, COME ON FOLKS! Let’s not kill training and education before it can begin by running everything through the lawyers. We are the experts, let peer review and some common sense solve the unwise risks associated with the trade, not a bunch of legal jargon and red tape.

It’s human nature that once we have a good thing going it’s easy to get comfortable and stop taking risks. I get it, but we can no longer rely on the certificates, degrees and processes of yesteryear to solve the staffing problems at our doorstep. We need to actively recruit, share, train, communicate and collaborate from contractors, schools, publishers, OEMs, reps, trade publications and industry bodies.

We need to try new things, be open to taking risks and stop defending our little piece of turf.

“I cannot teach anybody anything, I can only make them think.” ~ Socrates


Do you want the trade to get better? Is it your goal to see techs progress more quickly? Make a real difference?

Tear down the gates and focus on inspiring the spark of continuous learning in the trades 

That’s what’s on my mind today.

— Bryan




I was talking about dry contacts with one of my techs and he was looking 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…

Basically “dry” contacts is a switch that has no shared power source or supply integral to the control. A common example would be the contacts in a compressor contactor. The contactor has a 24v coil (in residential) but the power supply through the contacts doesn’t have any connection to the coil.

We see wet contacts every day when we connect a residential thermostat. A thermostat uses the same voltage/power source to power the control that it passed to the contacts from the “R” terminal.

This is especially important to differentiate when working on commercial equipment that may have different and varied control. The Danfoss ERC 213 shown above is an example where the compressor (terminals 1 & 2) may be of a different voltage than the wet contacts on 5&6 which must be 120V.

Here is a video where I describe this in more detail –

—  Bryan



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 based on one “hit”
  • Find the leak WITH BUBBLES whenever remotely possible, even after pinpointing with a detector.

— 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

If you are new to the trade… welcome

If you are young and new to the trade, we need you, but if you aren’t thoughtful you might get fired.

No offense, millennials often just have a different way of looking at work than their GenX bosses and trainers.

Here are my 8 top tips to help you make it a great a career.

#8 – Act interested (even when you aren’t)

I know sometimes your trainer can be boring, but when he is talking, look alive. Literally… I’ve seen apprentices who I wondered if they were actually dead… smelly… unresponsive… you get it.

When someone is attempting to invest in you it’s important that you listen up and pay them the respect they deserve.

#7 – Learn the names of basic tools

I know it can be confusing if you are new but read up enough so that when your trainer asks for “channel locks” you don’t say “what’s that”. This isn’t difficult to do and if you want to get familiarized with some tools you can look through the HVAC School tool list

#6 – Keep the music off and the earbuds out

Work isn’t the time to be distracted for any reason. That is unless you are listening to the HVAC School podcast… then it’s OK

#5 – Ask questions and listen carefully to the answers

Listen more than you talk. Give eye contact when your manager or trainer is speaking. If you don’t understand something be specific about the part you aren’t grasping.

#4 – Repeat back what you heard

Say “I want to make sure I understood you correctly” and repeat back what you understood rather than saying OK if you didn’t fully understand

#3 – Look professional

I don’t care if your boss or trainer looks like a slob, YOU dress according to the company policy and come to work looking well kept. Obviously, you need to dress job appropriate but people naturally respect someone who has a professional appearance.

#2 – Show up on time

Show up 15 mins early. Show up 30 minutes early! This isn’t complicated and bad traffic isn’t a valid excuse.


Your friends, Facebook, Snapchat… they can all wait. Give your work your full attention while at work

Oh… and while you’re at it… get good at working on and installing HVAC/R systems. That helps as well.

— Bryan

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