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  1. #1
    Join Date
    Apr 2001
    Location
    Tennessee
    Posts
    210
    I'm looking for opinions about checking freon charge in a heatpump when you have no choice but to run it in heat mode because its cold outside.

    What's the best way to know you're not over or under charged when superheat is for cooling mode? If you forced the unit to come on in cooling mode when the outdoor temp is under 45 degrees superheat will not be accurate. Or will it? Do we check subcooling or what?

  2. #2
    a good rule of thumb is to check your return and supply air temps, if you;re properly charged you should be discharging approx 30 degrees over return temp in heat pump mode

  3. #3
    Join Date
    Apr 2004
    Posts
    7,680
    Weigh it in.

  4. #4
    Join Date
    Nov 2000
    Location
    Waco, Texas, USA
    Posts
    6,153
    Originally posted by nyc/ac/man
    a good rule of thumb is to check your return and supply air temps, if you;re properly charged you should be discharging approx 30 degrees over return temp in heat pump mode
    Yeah maybe under normal circumstances but this system has a VS motor, undersized return intake and a dirty coil & blower wheel.
    "And remember my sentimental friend......that a heart is not judged by how much you love, but by how much you are loved by others" - Wizard of Oz.

  5. #5

    Thumbs up For Doc

    Good to go Doc the best method I've found and what I've always heard is to weigh it in!

  6. #6
    Join Date
    Dec 2005
    Posts
    3,819
    This is a way Goodman recommends charging heatpumps in the heat mode.

    126 above ambient, +/- 4, measured 6" from compressor on discharge line, works well when you have access to the discharge line without having to disassemble the unit, you loose about 15 degrees by the time the discharge gas reaches the service valve,through the reversing valve, so around 110 above ambient there.


    Adam

  7. #7
    Join Date
    Apr 2001
    Location
    Tennessee
    Posts
    210

    Clarification---Checking not charging..

    Of course weigh in is the most accurate method of charging, but I'm talking about a routine performance check to see if the unit is charged properly, not a start-up or repair. What's the most accurate way of checking Heat Pump charge in heat mode?
    Thanks for the replies so far.

    [Edited by freezeman on 02-08-2006 at 11:23 PM]

  8. #8
    Join Date
    Nov 2005
    Location
    Orange County Calif
    Posts
    128
    We always charge them in the cool mode, or weigh it in of course...But living in So Calif we dont get very cold very often...

  9. #9
    Join Date
    Sep 2003
    Location
    Northern Ohio
    Posts
    104
    Best way is discharge temp between compressor and reversing valve, like newoldtech mentioned. If your just doing a P. M. then just check it at the service valve @110 deg +/- 2 deg. But if your troubleshooting a possible charge or refrig. system problem then it's best to go through the hassle of checking it close to the compressor @ 126 +/- 2 deg. Temperature rise(supply - return temps) alone has too many variables in it to be accurate.

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