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Question DetailsAsked on 5/9/2017

Can you use r22a to top off a unit that is low

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1 Answer


R22a is not actually an ASHRAE registered refrigerant - it is a blend of propane (R290) and butane (both highly flammable) and is NOT a drop-in replacement for R-22a Freon - assuming your unit is Freon based rather than the newer R-410a, or some other more unusual refrigerant. (I was reading an article a month or two ago which listed a total of 23 different refrigerants in use in current A/C units, so you need to use the right refrigerant for your unit.)

Not only would you be going with a flammable gas (not a good idea in my mind), but the lubricating oil contained in the gas is highly unlikely to be compatible with your current unit - you should use the same type of gas and lubricating oil as your unit currently has (see nameplate). Mixing oil types can really gum up the works and cause sludge and carbon accumulation which can trash your unit.

Even if the unit could run non R22a, the operating pressures are very different, so assuming your unit could produce the diffferent pressure needed, your TXV valve in the unit would have to be adjusted to the different pressure - and many or most residential A/C units do not have adjustable TXV valves, so it would have to be changed out.

R422D is the only currently marketed drop-in replacement I know of for R-22 Freon - but you have to be sure it has the right type of lubricant. Sold in three different versions as I last saw, with three different lubricants - mineral oil (commonly the R-22 lubricant), ester lubricant, and synthetic oil.

My advice - don't do it. Below are also a few links to a HVAC blog and an EPA warning on this - not only is use of R22a illegal in R22 units, but if an HVAC contractor finds it in your unit in the future he might refuse to service it - or put in R-22 which would not perform properly mixed with R-22a - not to mention the unit has not been designed to be safe using a flammable gas refrigerant.

Answered 3 years ago by LCD

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