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  1. #1
    Join Date
    Jun 2004
    Location
    MidWest
    Posts
    64
    Maybe it does not sound funny to you but it does to me. A 15+ year vet. told me he thinks we should convert a 408A walk-in cooler to 409A by changing out expansion valves and refrigerant but leaving 7 year old Cope tin can since I quote " It is old and loose enough to take the change. I have done it before and it worked fine." Your thoughts?

  2. #2
    Join Date
    Nov 2003
    Posts
    501
    I don't think it would work too well. 408a is a 502 replacement, and 409a is a r12 replacement. They run at totally different pressures. Sure you could do it, but I don't think that the unit would pull freezer temps anymore.

    You're best bet would be to leave it as 408a, or even change the oil to POE and change it to 404a.

    Why does he want to change it anyway?

  3. #3
    Originally posted by referjunkie
    Maybe it does not sound funny to you but it does to me.
    A 15+ year vet. told me & I quote " It is old and loose enough to take the change. I have done it before and it worked fine." Your thoughts?

    I personally dont know what a 502 unit, converted to 408, is going to be when it's reconverted to 409, an R-12 type of gas.

    But why bother?
    What's the application?

    And since the unit is so old already, why not just do it new?
    Too many "if's" to be able to suggest an appropriate answer.

  4. #4
    Join Date
    Feb 2004
    Location
    Medford Oregon
    Posts
    807
    Many old timers converted R12 LT to R502 LT to gain
    15/20% capacity. Does this mean that reversing this
    will lose 15/20% capacity. That's assuming that it
    may work which is questionable. Something to ponder.

  5. #5
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,478

    R408A to R409A?????

    What's wrong with this MT cooler system's operation on R408A that would lead anyone to want to change the refrigerant?

    As others have replied, R409A is a completely different refrigerant than R408A. In this case the system will in fact run if you also change the TXV, but since the R409A requires a higher displacement compressor the capacity will drop by about 1/3.........I don't think that's what your Co-worker wants to happen.

    I still have a few units out there that were originally set up for R502 medium temp, now running either R408A, HP80 or R22. These units were dual rated for either R22 or R502 MT ans R502 usually demonstrated a slight capacity improvement over R22.

    So if an old R502 MT box loses its charge, I'd switch to R22. It typically only requires a thermostatic element change on the TXV, a change of gas and you're good to go.

  6. #6
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,478
    Originally posted by rocket
    Many old timers converted R12 LT to R502 LT to gain
    15/20% capacity. Does this mean that reversing this
    will lose 15/20% capacity. That's assuming that it
    may work which is questionable. Something to ponder.
    I'm an old timer and I never did that. My Dad did a lot of R22 LT to R502 LT conversions back in the sixties. The only time I've ever seen a compressor rated for LT R12 running LT R502 is on slide top ice cream display cabinets with Copeland K-Body LT R12 compressors, a CPR and R502.

  7. #7
    Join Date
    Feb 2004
    Location
    Medford Oregon
    Posts
    807
    there was an old R12 LT frozen juice case using Copes
    KAG-0050, we called it a slush case. I converted quite a few of these over to R502 in the late 60's, then it was a frozen juice case. Though never rated for R502, the new KAG-0050 is now rated for R404A LT. (KAGB-05E)

    I did it as well as most of my coharts in those days

  8. #8
    Join Date
    Jun 2004
    Posts
    182
    I know you stated this was a cooler but here is capacity comparision R-12 to R-502. This is at -10/110 with a KAL Copeland compressor. R-12=4670 btuh. R-502=7790 btuh.

    Bottom line is you will see quite a drop in the system capacity.

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