Refrigerant Charging Basics For Air Conditioning & Heat Pump Systems
Before I start on this one… At HVAC School we focus on a wide range of topics, many of them are very basic. My experience as a trainer for over 16 years has taught me that no matter what I assume others SHOULD know, it doesn't change that fact that they often do not. This […]
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Refrigerants, Flammable & Toxic
There has never been a more complicated and confusing time surrounding refrigerants that what we are in right now. We are seeing flammable HC (Hydrocarbon) refrigerants with increasing regularity and EPA rules that just changed appear to be changing again With all this tumultuous change it's important to know what to look for in refrigerants […]
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Liquid Line Solenoid Valves: Long Line Applications
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 […]
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Crankcase Heaters
Belly band crankcase heater When I first started in the trade as an apprentice, we worked on a lot of Trane heat pumps that used crankcase heaters. These crankcase heaters slid into the compressor sump on the big orange Tyler reciprocating compressors, like the one below. It was very common for these heaters to break […]
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The “5 Pillars” of Residential A/C Refrigerant Circuit Diagnosis
Suction pressure, head pressure, subcooling, superheat, delta T. Taking all five of these calculations into account on every service call is critical. Even if further diagnostic tests must be done to pinpoint the problem, these five factors are the groundwork before more effective diagnostics can be done. I would also add static pressure as an […]
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What does “Saturated State” mean for Techs?
As we often do in these tech tips, we will start with the common and more practical explanation of saturation and then move to the more technical and nerdy explanation later. When we say “at saturation” or “saturated” in the HVAC/R trade, we are generally referring to the refrigerant that is in the process of […]
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Weighing Refrigerant In and Out
If you don't use a scale every time you add or remove refrigerant, I suggest you begin doing so immediately, if not sooner. Weighing in while charging is fairly obvious, and it's useful so you can keep track of what you are using and how much to charge a customer. When you have a system […]
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Refrigerant Basics
A refrigerant is anything we use to move heat from one place to another using the compression refrigeration circuit. However, the history of refrigerants and the different kinds is quite diverse and interesting. Have you ever noticed how your skin feels cool after you apply rubbing alcohol to it? For a long time, scientists and […]
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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. This does not happen… at least not like that. What can and does happen is called “fractionation.” Refrigerant blends are composed of a mix of refrigerants with different vapor and liquid PT characteristics, […]
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