Regular Guest
Saw an ad in an HVAC mag about R-421 being a direct replacement for R22 and it meets the non-ozone requirements coming up. Why don't I hear more about this? All I hear about is R-410a. Any thoughts on 421?
Professional Member
It looks like R421A is a blend of R-125/R-134a (58/42). R421B is R-125/R-134a (85/15). R507 is the azeotropic blend of these two - R-125/R-143a (50/50). So it looks like somebody decided to change the composition of R507 slightly and patent it. It's a blend of HFC's and would need and oil change if you were to put it in a mineral oil system. There are plenty of blends like this already, so I wouldn't get too excited.
Professional Member
Sorry, made a mistake. 507 has 143a not 134a. 421 is still a hfc blend though.
Professional Member
Any idea when can i find more solid info on these refrigerants?
Professional Member
Walmart has been converting rack systems from R22 to R422D. We did one conversion w/o problems and have been involved in another one where they are having problems w leaks. The oil is being changed but it is still mineral oil of the same viscosity.
Not sure at this point whether the seal problems are due to the refrigerant doing something to the seals or due to the vacuum being pulled prior to the recharge. (movement and reseating of the seals?) Could also be bad technique, the outfit that did the leaky system didn't go through and tighten all of the valve caps. The system we did had a couple small leaks afterwards but no more than might be expected normally and has been relatively trouble free.
Otherwise the only problem we have seen is that no one stocks the R422D
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