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HVAC School - For Techs, By Techs

Apr 23, 2019

Do you need different gauges for each refrigerant? In today's short podcast, we discuss the answer to this common HVAC question.

When we first started using R-410A, many people warned us that we'd have to use a separate set of gauges when working on R-410A systems. That's because R-410A systems use POE oils, not mineral oil, and they are not compatible. While it is true that R-22 and R-410A systems use different oils, there is no need to worry about using separate gauges for each type of system. Actually, some manufacturers recommend using a little bit of POE oil in mineral oil systems.

What you cannot do, however, is mix the refrigerants themselves. Many of the gauge hoses have quick disconnects, which cause some confusion regarding the de minimis rule. (The de minimis rule permits tiny refrigerant losses from regular servicing, and de minimis DOES protect us.) However, we aim to keep our hoses clear anyway. We do that by bleeding liquid refrigerant back into the suction line after servicing.

So, the real concern doesn't lie in which refrigerant we use with our gauges. The real issue is about taking steps to avoid contamination of the entire system and stay in compliance with EPA standards. Mixing POE and mineral oil does not negatively affect a refrigeration system; however, moisture does pose a threat to POE oil. Again, the core issue deals with best practices: flushing and purging hoses, minimizing the risk of hydrostatic pressure, avoiding venting, and avoiding mixing refrigerants.

Of course, you don't have to worry about any of these problems and practices if you check the charge without gauges. Using probes is an easy way to get good measurements without worrying about contamination


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