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RS44 or R424a in place of R22

Hello all,

I have an R22 Mitsubishi that needs some servicing and I want put a suitable replacement for R22 in it.
I expect this unit to remain active for many years and want to use a refrigerant that won't be phased out.

Does anyone have any experience with any of the drop in replacements like RS44 - R424a?
A supply house suggested R407c but that works on a different and incompatible oil.


  • ChrisJ
    ChrisJ Member Posts: 11,784
    If it's a good tight system, why not keep the proper refrigerant in it?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    JUGHNE Member Posts: 8,533
    edited January 2016
    If it would pressure test good at 300 PSI for an hour, I would certainly replace the Schrader valves and caps, put R-22 back in it . It can't hold that much weight wise and there will be R-22 around for quite a while is some shape or form. What does it have for oil now?

    There is a good chance that many HVAC people are stockpiling even hoarding R-22......(heaven forbid....damn capitalists anyway! ;) ) so will probably be available, you just have to pay more.
  • John Mills_5
    John Mills_5 Member Posts: 935
    22 is rather low priced at the moment and is proven. For the couple pounds you'd have put in, you won't go broke. So many different alternatives out there. I'm most familiar with NU22b, made locally and well supported.
  • Empire_2
    Empire_2 Member Posts: 2,343
    NU 22. Is the closest drop in ref. virtually matching t&p chart with out changing oil. Purple can at the time r-22 was going through roof price wise, it was the best replacement available. Take a look at your tp chart. Will not get anything closer.