#Superheat

Tech Tips:

One Way to Picture Superheat and Subcool
By:Matthew BrunerIt took me years to build a picture in my head of what superheat and subcool mean. They were these strange words that dropped out of nowhere when I entered the HVAC world, and in the midst of grappling with so many other things, I could tell they were very important. Over time, I […]
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How to Set a Charge by Superheat
By:Bryan Orr So many techs are OBSESSED with how to set the charge rather than understanding all of the readings, specs, and system conditions that go into optimum system performance. Before “setting the charge,” I suggest (nay, I REQUIRE) that you do a full visual inspection of the system, have an understanding of the initial […]
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Why and How to Adjust a TXV/TEV
By:Bryan Orr As we discussed in an earlier podcast, a TXV maintains a specified and constant superheat at the evaporator coil outlet. It does this through a balance of forces between the bulb pressure (opening force), equalizer pressure (closing force), and spring pressure (closing force). We can actually adjust the spring pressure on some valves. […]
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What’s So Wrong With “Beer Can Cold”?
By:Bryan Orr 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 […]
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Negative Superheat? Time to Check Your Tools
By:Bryan Orr 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 […]
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What Should My Superheat Be?
By:Bryan Orr  The most common—and often most frustrating—questions that trainers and senior techs get asked sound something like this: “What should my ______ be?” or “My _____ is at ______. Does that sound right?” Usually, when the conversation is over, both the senior and junior techs walk away feeling frustrated because the junior tech just […]
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The “5 Pillars” of Residential A/C Refrigerant Circuit Diagnosis
By:Bryan Orr Suction pressure, head pressure, subcooling, superheat, delta T. Taking all five of these calculations into account on every service call is critical. Even if you must do further diagnostic tests to pinpoint the problem, these five factors are the groundwork before more effective diagnostics can be done. I would also add static pressure […]
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The Case for Checking the Charge Without Using Gauges
Jim Bergmann and I recorded a podcast for HVAC School that covered when and how to check the refrigerant circuit without connecting gauges. Listener Joe Reinhard listened several times and wrote up this summary of what he gained from the episode. I edited it lightly, but most of this is his work. Thank you so […]
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Podcasts:

Expansion Valves – What Does and Doesn’t Matter?
By:Bryan OrrJoe ShearerCorey CruzMatthew Taylor    This podcast features a lively discussion on expansion valves, particularly thermostatic expansion valves (TXVs or TEVs), with a panel of expert guests – Corey Cruz (a market refrigeration tech), Matthew Taylor (head of refrigeration service at Kalos), and Joe Shearer (with Precision Air Conditioning). The conversation kicks off […]
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Q&A – How to Learn Superheat & Subcooling – Short #191
By:Bryan Orr  In this short podcast episode, Bryan answers an audience member's question and explains how to learn superheat & subcooling, two fundamental aspects of the HVAC/R trade. You can submit questions of your own at https://www.speakpipe.com/hvacschool. Saturation is when a substance is in the liquid and vapor state in the same place. Eugene Silberstein […]
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EEV Types – Short #193
By:Bryan Orr  In this short podcast episode, Bryan explains electronic expansion valve (EEV) types. EEVs perform the same function as TXVs, but they operate electronically, not mechanically. The EEV makes sure that the evaporator is full of the right amount of refrigerant at saturation; it doesn't just affect evaporator pressure. We don't want high […]
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How a TXV Works and Why I Call it a CSV
By:Bryan Orr In this episode of HVAC School, Bryan talks to Leslie about the deceptive TXV. Thermostatic expansion valves, also known as TXVs or TEVs, are metering devices that maintain superheat. They contain an external equalizer. External equalizers give the pressure reading that you would normally take with a suction gauge at the end of […]
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The 5 Readings Every Tech Must Know Well
By:Bryan Orr In this episode of HVAC School, Bryan covers the “5 pillars of refrigerant circuit diagnosis” and why they matter. They are: Superheat Subcool Suction pressure Head pressure Air temp split (delta T)   These 5 readings give you a holistic idea of the A/C system. Instead of getting hooked on checking only superheat […]
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Full System Diagnosis – There is More to Check
By:Bryan Orr In this episode, Bryan goes back over the basics and stresses the importance of diagnosing the whole system. I'll cut to the chase: inspection is NOT overrated. Inspections help you become more familiar with HVAC systems and can help you catch on to minor issues before they spiral out of control. Check air […]
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Refrigeration Tips For A/C Techs
By:Bryan OrrJeremy Smith In this episode of the HVAC School Podcast, Bryan talks with Jeremy Smith about refrigeration tips, terms and processes. They also cover the similarities and differences between A/C and refrigeration. Being on-call as an A/C tech is not all that different from being on-call as a refrigeration tech. Similarly, the principles of […]
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