One of my techs (Jim Walch) mentioned to me that another common “double trap” style issue that comes up often is techs and installers running a drain too far into a condensate pump.

When you run the system drain too deep into the pump reservoir the water level can rise high enough to cover the drain end. This can create the same type of “airlock” you get with a double trap.

When draining into a condensate pump only extend the drain tube 1″ or so into the reservoir of the pump to prevent the water from rising and covering the end. Also, make sure to wire up the overflow switch on the pump in series with your system condensate switch so that whether the pump itself fails or the system drain pan has a blockage it will shut the system off.

Simple stuff, but it can prevent thousands of dollars in damage.

— Bryan

While there are various line lift, sizing and trapping guidelines depending on oil and refrigerant type there is one guideline we can all understand easily and remember to apply and this is to slope suction lines towards condensing units / compressors.

Keeping the suction line sloped toward the compressor, especially with long, overhead lines helps to return the oil back which assists with capacity and lubrication resulting in fewer issues.

A good general rule is to slope the suction line 1/2″ per 10′ of horizontal run.

Short and simple but often forgotten.

— Bryan


There are all sorts of complicated refrigerant acronyms.. HFC, HCFC, CFC and well as the mythical Zeotropic, Azeotropic and near Azeotropic… Let’s simplify

CFC = Refrigerant that is really bad for the Ozone. They are almost all gone. R-12 and R-11 are examples

HCFC – Refrigerants that are bad for the Ozone but not as bad as CFCs. Most common is R22.

HFC – Refrigerants that aren’t bad for the Ozone but they do add to global warming through the greenhouse effect. Most common is R410a.

When it comes to the whole zeotropic, azeotropic thing the main thing you need to know is that older refrigerants were often just one type of molecule. That meant that they condensed and evaporated consistently and it didn’t matter if you added them to the system via vapor or liquid. These simple refrigerants were known as PURE refrigerants.

Today we mostly work with HFC and HCFC blends. These blends can be Azeotropic, which means they blend together and act as one refrigerant or Zeotropic which means they have “glide” resulting in different boiling and condensing temperatures of the refrigerants mixed in. Rubber meets the road in a refrigerant with high glide when you need a separate “condensing” and “boiling” termperatures on the PT chart. R407C is an example of a high glide zeotropic refrigerant where R410a has nearly 0 glide. While R410a is TECHNICALLY zeotropic is is so close to being Azeotropic that the industry coined the phrase near-azeotropic.

In all blends, you must charge the refrigerant as a liquid to prevent the refrigerants from separating in the vapor state. As always, when charging liquid in the suction line, add it slowly and carefully, allowing all the liquid to boil off before entering the compressor to prevent flooding/slugging.

— Bryan


One of the most common mistakes I hear techs make is confusing Zero ohms with infinite ohms. The fuse above is showing near zero Ohms which means a good electrical path with very little resistance.

If there is a perfect path it would have zero ohms (which isn’t actually possible unless you happen to be testing a superconductor).

If there is no path, the circuit has infinite ohms. This would be shown as Open or OL or something similar.

Often when I ask what ohm reading a tech is getting they will say “none”… None could easily mean zero or infinite so it’s important to clarify.

Once again.

Zero ohms = shorted / closed / directly connected

Infinite ohms = open/ no path

Try to remember to say either Infinite or zero instead of  “no ohms” or “none” to avoid confusion

— Bryan

I ‘m writing this a few hours before the “big game” in 2018, so I don’t know the outcome of the Patriots vs. Eagles nor does it matter for the sake of this article.

I’ve been pulling against the Patriots and Tom Brady ever since he supplanted Drew Bledsoe as the quarterback in 2001 as the young gun replacing the older pro.

I dislike Tom Brady in the same way and for the same reason that many football fans don’t like him, he is infuriatingly good!

I can make up reasons to dislike Brady, like inflate-gate or the practice filming scandal. The real reason for me is that I like an underdog story , and Tom Brady and the Patriots are the Alpha wolf of the league and I’m just plain sick of them winning.

As much as it pains me to do so, I must admit that Brady is likely the best QB of all time and he has a lot of traits that we can learn from in our field of expertise.

Have a Long-Term Vision

Many don’t know that Tom Brady grew up in California and was a big 49ers fan (just like me, the 49ers part not the California part). In college, he chose Michigan because he felt it was the best long-term opportunity for him to become a top-level quarterback even if he had to play as a backup to Brian Griese for two seasons. During his time as a backup Brady experienced a lot a doubt and even considered seeking a transfer to Cal, in the end, he stayed at Michigan and had to fight for playing time all the way through his college career. Because of this he was never considered an elite college quarterback and was drafted with the 199th pick in the draft.

Many of us make decisions based on short-term goals and with temporary challenges top of mind. In order to be the best of the best, you need to make choices based on the long-term vision and choose opportunities not only for what it means tomorrow but what it can do for your entire career.  That co-worker who makes you angry or that other job that will pay you a dollar or two more may tempt you to make a change, but is it the right change for the long term?

Make decisions now that the version of you 10 years from now will look back and thank you for. Choices like spending time reading instead of watching TV, saving instead of spending, making time for your family instead of going out and having a beer, and choosing a job based on how much you will grow and the opportunities that lay ahead rather than just the paycheck.


Tom Brady isn’t a stellar athlete when you compare him to most other guys in the NFL but what he does better than almost anyone is prepare for his opponent. He can look out at defense and tell instinctively what they are going to do and which safety he needs to move just a few feet by “looking him off” to get the ball to an open receiver.

That “instinct” doesn’t come from natural skill, it comes from preparation, coaching, and attention to detail.

Jim Bergmann said it best when he told me:

Guys will come up and tell me that they have 20 years of experience and their way works just fine. I tell them “No, you have 1 year of experience, 20 times over”

Experience “playing the game” alone isn’t enough to give you an edge. You need to –

  • Read and Study, stay up on the latest tools, techniques, and technology
  • Seek out good coaches, people who will challenge your thinking and get you to the next level of detail and precision
  • Look for vulnerabilities in your opponent (the equipment) and know them like the back of your hand

If there is one part or process on a piece of equipment you serve that you don’t understand then stop and take the time to understand it before you move on.

Use Tools to Your Advantage

If your receivers catch the ball more easily with a few PSI less in there then, by all means, do what you need to do! In all seriousness, I think the Patriots inflated the balls to the minimum allowed in the warm locker room and when they went out on the cold field the pressure in the balls dropped below the allowable limits (Gas laws in action, but I digress).

Sometimes using new, fancy tools can feel like cheating but anything that increases accuracy like the Testo smart probes or saves time like the Pro-Fit is worth considering. Use any advantage you can get and high quality, well-maintained tools can make a huge difference in the hands of a good tech.

Seek Out Good Coaching

Do you think Tom Brady would be Tom Brady if he had been drafted by the Browns or the Bears? In our trade, you have a huge opportunity to find mentors online that you never had before. I find myself calling, emailing and texting my friends and mentors all the time with questions, some of them pretty stupid. If you really want to be exceptional you need to know people who can give you good advice and even set you straight when you need it. Do you think Bill Belichick is easy on Tom Brady? Do you think Tom Brady would be Tom Brady if he was? Find a few pros who aren’t afraid of calling you out in order to make you better.

Enjoy Your Work

Tom Brady is a fierce competitor who doesn’t want to retire even though he certainly doesn’t need to keep playing. I would argue that our work is far more important to the world than football and it’s also no less challenging or interesting. Choose to engage with your work and enjoy it, keep those competitive juices flowing by doing a better job every day than the day before.

Keep Your Eyes Downfield

Sure, you can run with the ball yourself, but as a quarterback, you are much more effective when you look to pass it off to others and give them a chance to shine. Those of us that try to do it all ourselves will just break our backs and like a quarterback who runs too much, likely end up with a concussion. Invest in the next generation of techs and pass the ball whenever you can to give them a chance to gain experience.

Don’t Give Up

How many times have the Patriots come back in situations when we all wrote them off?

 It’s almost like they know something the rest of us don’t. I would argue that they do.

The Patriots know that none of them are going to throw in towel no matter how bad it gets. If they make a mistake they don’t spend time arguing and pointing fingers they just move on, learn what there is to learn and start making touchdowns when it counts.

Most of us get beat down and fall into a rut after a while. Bad things happen, customers get upset, we make a misdiagnosis and we start to think that’s just how it goes. The truth is, that is just how it goes, but that is no reason to adopt a losers attitude. You have a valuable skill in a trade with endless possibility, no matter what you’ve experienced you have an opportunity to learn from those experiences, come back and win the game.

Set goals, learn, grow and don’t give up on your career. We are all on the same team and the team needs you.

— Bryan




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 vice grips to tighten down their gauges “just in case” when they have a hard time finding a leak or a vacuum that won’t pull down.

Seriously… No, Stop, Please

Gauge manifold valves can be tightened and loosened with your fingers, you don’t need to crank down on them. When you do you can ruin the seals and then you really will need to overtighten them every time.

If your gauge seals need to be replaced then get new seals and replace them, but being a bit more gentle when opening and closing, storing them more carefully and even putting a drop of refrigerant oil on the seals from time to time will keep them working for a long time.

Especially with modern, digital gauges (like my favorite, the Testo 550) you are making a big investment, treat them well.

Finger tight only.

— Bryan

On an energized , intact circuit you will read voltage across an OPEN switch not across a CLOSED switch when testing with a voltmeter.

Both sides of a closed switch are electrically identical (or at least very close) and therefore there should be no movement of electrons between the leads of your voltmeter.

I have seen many new apprentices get confused when they measure across the points of an energized (closed) contactor or between two energized low voltage circuits and they measure 0 volts.

Voltage measurement is always a measurement of potential difference between two points not simply a measurement of how much “Electricity” can be measured at one point.

Across a closed switch = 0 volts (or if it does display voltage it is the voltage drop across the switch)

Across an open switch = applied voltage

— Bryan

The piston (fixed orifice) and TXV (Thermostatic Expansion Valve) are the two most common metering devices in use today, with some modern systems utilizing an electronically controlled metering device called an EEV (Electronic Expansion Valve).  It should at least be noted that there are other types of fixed orifice metering devices like capillary tubes, but their use is not common on most modern A/C systems though you will see them in refrigeration.

While the compressor creates the pressure differential to get the refrigerant moving, by decreasing the pressure on the suction and increasing the pressure on the discharge side, the purpose of the metering device is to create a pressure drop between the liquid line and the evaporator coil or expansion line (the line between the metering device and the evaporator when there is one). When the high-pressure liquid refrigerant is fed into the metering device on the inlet the refrigerant flows out the other side and the immediate pressure drop results in an expansion of a percentage of the liquid directly to vapor known as “flashing”. The amount of refrigerant that “flashes” depends on the difference in temperature between the liquid entering the metering device and the boiling temperature of the refrigerant in the evaporator. If the difference is greater, more refrigerant will be “flashed” immediately and if the difference is less than less refrigerant will be flashed.


A piston is a replaceable metering device with a fixed “bore”. It is essentially a piece of brass with a hole in the center, the smaller the bore the less refrigerant flows through the piston and vice versa. The advantage of a piston is that it is simple and it can still be removed, the bore size changed and cleaned if required.


Some piston systems also allow the reverse flow of refrigerant as shown in the diagram to the above. In a heat pump system when the reversing valve is energized (cool mode), the unit will run in cool mode and the refrigerant will follow the path indicated on the bottom.  This seats the piston so refrigerant must pass through the orifice.  With the reversing valve de-energized the flow reverses.  This unseats the piston and allows the free flow of refrigerant.  In this case, there is a metering device in the condensing unit (outside unit) that meters the flow of refrigerant in heat mode and one inside that meters in cooling mode.


The TXV can vary the amount of refrigerant flow through the evaporator by opening and closing in response to evaporator heat load.  compared to a fixed orifice a TXV operates more efficiently in varying environmental conditions (theoretically at least).

To operate, the TXV has a needle and seat that restricts the flow of refrigerant and acts as the orifice.  This needle, when opened, allows more refrigerant to flow and, when closed, restricts refrigerant flow.  There are three factors that affect the flow of refrigerant flow through a TXV.  A sensing bulb filled with refrigerant exerts force to open the TXV.  Since gas pressure increases with a rise in temperature, the bulb, which is attached to the suction line after the evaporator coil, “senses” the temperature of the suction line.  If the suction line becomes too warm, the additional pressure created by the heated refrigerant opens the TXV more to allow additional refrigerant flow.  A spring inside the bottom of the TXV exerts pressure to close the valve.  An external equalizer senses pressure in the suction line after the evaporator, and also works to close the valve. In essence, the TXV is a constant superheat device, it sets a (relatively) constant superheat at the evaporator outlet by balancing bulb, spring and equalizer pressures.

The primary method of charging a system changes based on the type of metering device. A piston system uses the superheat method of charging and the TXV uses the subcooling method of charging.

No matter what primary method of charging you use it is still important to monitor suction pressure (Evap temperature) head (condensing temperature), Superheat, subcool and delta t (or some other method of air flow verification).

While a TXV and a piston function differently the end result is a pressure drop and boiling refrigerant in the evaporator.

— Bryan

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