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Thread: R22 to 410a evaporator flush

  1. #1
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    Mar 2009
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    R22 to 410a evaporator flush

    I have to install new carrier 2 ton condenser unit on a system with an existing aruf25b14 Goodman air handler that was installed a year ago on an old r22 condenser.
    I haven't done one of these conversions before and don't know the oil compatibility issues, but I am sure there is some. I don't want any goo clogging a new unit. I am installing a new line set so the only thing I have to flush is the evaporator. Is there an actual procedure I can find for this somewhere. Or do I have to wing it.
    Or, is there someone who has some experience with this kind of flush out there? I usually do an acetone or a r11 flush, or both on evaps and have had good success with them. I just don't know if I will have an issue getting all traces out of the evaporator. I haven't had the opportunity on the Goodman unit. I usually install the whole system.
    Any recommendations.
    I usually work on commercial HVAC, and auto air, but worked for Trane as a controls specialist before I retired. Now flipping homes.
    Any responses would be appreciated.

  2. #2
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    Oct 2009
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    I would use nitrogen to push out the old oil.I don't think you need to flush ,unless it was a burnout.It won't hurt to have a small amount of Mineral oil left.I have done this same type of job.Never flushed with a chemical.Never had a problem .Only used Nitrogen to push out the old oil .If switching from from R22 to R410A, check with Goodman .You need a different Accutator or TEV ,for R-410A.Make sure the Evaporators coil is approved for R410A.Its only a year old,So probably is ok, Double check.

  3. #3
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    Mar 2009
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    Thread Starter

    flush

    Quote Originally Posted by Gleng View Post
    I would use nitrogen to push out the old oil.I don't think you need to flush ,unless it was a burnout.It won't hurt to have a small amount of Mineral oil left.I have done this same type of job.Never flushed with a chemical.Never had a problem .Only used Nitrogen to push out the old oil .If switching from from R22 to R410A, check with Goodman .You need a different Accutator or TEV ,for R-410A.Make sure the Evaporators coil is approved for R410A.Its only a year old, So probably is ok, Double check.
    Yes I have the 410a TXV that came with the air handler. I made sure I had it.
    There was not a burn. The compressor just has bad valving, so it has to high of pressure on the low side and to low a pressure on the high side. The unit is cooling, but it runs constantly causing high electric usage. So you can have a bit of mineral oil in with the 410a oil and it will not gel? Like ester oil and mineral oil on a car ac retro fit?
    Thanks for the info that makes things easier.

  4. #4
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    Make sure to register the OD unit, if you went with a matched Goodman OD unit, chances the manufacturer warranty will be 10/10. Guessing with the Carrier it will be 5/5. Probably to late as guessing you have the unit already.

  5. #5
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    Aug 2002
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    There is NO oil compatibility issues. Just blow the existing equipment with N2. Done

  6. #6
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    Blow it out with nitrogen. The old standard was <5% mineral oil ok with HFC refrigerant. If concerned or have a problem, test with a refractometer and change oil after operating if excess mineral.
    Should not be a problem on a ahu tube/fin. Only times I've seem where a major problem has been with plate heat exchangers where they would have to be removed and flushed or replaced if charged with mineral oil & R-410a or R-134a

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