#r-410a phase down

Tech Tips:

This tech tip was written by Don Gillis with Chemours. Thanks, Don! You’ve probably heard it way too many times now: A2Ls are coming. While we’ve heard a lot about what “A2L” really means and the R-410A phasedown timeline, there isn’t a lot of public information about what to expect on the service side. I’ve […]

R-410A Phase-Down Update

This tech tip is an overview of the livestream by the same name, featuring HVAC School contributors Matt Bruner, Roman Baugh, and Adam Mufich, as well as special guests Don Gillis, Dr. Chuck Allgood, and Jason Obrzut. You can watch the full livestream HERE. These gents also gave the “Flammable Refrigerant Update” at the 2023 […]

What Techs Need to Know About A2L Refrigerants

This article is based on the recent HVAC School podcast episode on A2L refrigerants with Jason Obrzut. You can listen to that podcast HERE. Jason is a member of the AHRI Safe Refrigerant Transition Task Force and has co-authored Refrigeration and Air Conditioning Technology (the RACT manual). You can access AHRI’s A2L refrigerant resources at […]

What Is A2L Mitigation Going To Look Like? W/ Clifton B.

In this podcast, Bryan and Clifton discuss the upcoming transition to A2L refrigerants, like R-32 and R-454B, and what A2L mitigation is going to look like. These mildly flammable refrigerants will be used in place of R-410A for residential air conditioning systems due to an HFC phase-down driven by legislation and international agreements. They […]

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In this short Q&A podcast episode, Bryan answers a listener-submitted question about superheat, including what it is and how we measure it.

Superheat is the number of degrees a refrigerant is above its saturation point. The saturation point is where you will have a liquid-vapor mix, so superheat only exists when a substance is a vapor. Saturated refrigerant should only exist in the evaporator and condenser, during which it is being boiled or condensed.

We usually measure superheat at the evaporator coil outlet and compressor inlet. The superheat at the evaporator outlet is usually around 5-14 degrees Fahrenheit, and it’s often between 10 and 20 degrees at the compressor inlet (compressor superheat). However, many systems try to get lower superheat values, and some manufacturers may require higher superheat values at the compressor inlet to prevent liquid refrigerant from getting into the compressor. Accumulators can help keep liquid refrigerant out of the system as well. We may also measure superheat coming out of the compressor on the discharge line (discharge superheat); this superheat may exceed 100 degrees Fahrenheit. Discharge superheat can let you know if the compressor is overheating the oil and causing breakdown or carbonization.

We use superheat to set the charge for fixed-orifice metering devices (as opposed to subcooling for TXVs), as superheat is a measure of how well we’re feeding our evaporator coil. When the system is off, the superheat will be 0. A system will equalize, and the refrigerant will be at saturation when that happens.

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