# 421a?



## Tony Pullen (Oct 21, 2011)

anyone know anything about the refrigerant 421a? Supposed to be a direct replacement for 22. opinions? I was told it was a blend of 125 and 134.:huh:


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## beenthere (May 30, 2009)

You have to change the metering device. It takes a larger orifice. And on TXV systems, will usually take a larger TXV.

So if you were converting a heat pump, its would be a lot of work.


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## Tony Pullen (Oct 21, 2011)

I can't see that , seeing as though the pressure temp. relationship is almost identical at low temps and within 2 or 3 psi even at high temps....that is verrrrry close. My only concern is the oil compatibility.


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## beenthere (May 30, 2009)

Its in the instructions for the conversion.

http://www.certifiedrefrigerant.com/r-421a_retrofit_procedurerev02.pdf


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## Mikey (Jun 21, 2012)

what if its a piston


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## beenthere (May 30, 2009)

Mikey said:


> what if its a piston


It would need a larger piston.


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