How to Use an Adjustable (Crescent) Wrench, Pipe Wrench and Tongue & Groove (Channel Locks) Wrenches
My grandfather is a really interesting guy. He grew up working in the Pennsylvania coal mines starting at the age of 7 or 8. Then, he worked as a well driller, was a plumber, went to HVAC school, did some gas work, worked a while as an electrician, became a welder, was a diver, and […]
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What are Dry and Wet Contacts?
I was talking about dry contacts with one of my techs, and he looked at me like I had three heads—and one of them was on fire. So, I figured it would be good to cover the difference between wet and dry contacts in a tech tip. Basically, “dry” contacts are switches with no shared […]
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Non-non-condensables
  Flowing nitrogen while brazing and pressurizing with nitrogen are great practices. Putting nitrogen in with the refrigerant? Not so much. Nitrogen is a “non-condensable” gas because it cannot be condensed (under normal conditions). However, nitrogen is just one of the non-condensables. First, let's talk about what a non-condensable gas is. Any gas that does […]
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What’s So Wrong With “Beer Can Cold”?
First off, if you've never heard the term “beer can cold,” you are either not in the trade, or you have been living a pretty sheltered existence. I started as a tech apprentice when I was 17 years old, and on my first day in the truck, my trainer grabbed the suction line of a […]
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Condensation – It Isn’t Where Hot Meets Cold
Photo by Stephen Rardon I hear it all the time. Someone will talk about undesired condensation on an air handler cabinet, on a supply air duct, in a ventilation duct, or on a vent like the one above. In reply, someone will inevitably say, “Condensation occurs where hot meets cold.” Early on in my career, […]
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Changing Refrigerants and Why it Matters to You
Graphic Courtesy of Danfoss On 8/8/17,  the United States court of appeals struck down an EPA phaseout of HFC refrigerants under the Clean Air Act on the basis that the Clean Air Act only gave the EPA the right to regulate ozone-depleting substances. However, many of us figured that the decision was likely to be […]
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Coil Cleaners: A Guide to Which Cleaners to Use in Various Applications
Spring and fall are the seasons where all service technicians get turned into janitors. Some techs see this as a chore and don’t particularly enjoy the routines of checklist maintenance. However, it is important to remember that the “shoulder seasons” provide an opportunity for us to perform vital maintenance on systems in order to keep […]
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Negative Superheat? Time to Check Your Tools
I was fresh out of school, working as an apprentice at my first real HVAC job, and I was listening in on a shop conversation between a few techs. They were talking about finding so many overcharged systems. One of the techs turns to me and says, “I had a unit yesterday that was so […]
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Does Refrigerant Get Old or Wear Out?
Over the years, I have heard technicians say that refrigerant can wear out or “lose its blend” by sitting in a tank. Refrigerant does not wear out or “lose its blend”… at least not like that. What can and does happen is called “fractionation.” Refrigerant blends are composed of a mix of refrigerants with different […]
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