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Checking heat pump charge when it's in heating mode

Discussion in 'Residential' started by Andy G, Jan 29, 2009.

  1. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    I've got a question--most heat pumps have a refrigerant charging chart for the cooling mode, but not for heating mode. If you're working on one in heating mode, when it's about at the freezing point outside, how would you decide if the charge is right or not and do better than a guess?

    Don't tell me to make a tent around it and run it in cooling--I'm not going to do that.:biggrin:
  2. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    There's a more experienced tech here who measures the temp on the vapor line and goes by that. I have a clamp meter and can measure that accurately. Is this a good way to go? And if so, what should I expect?
  3. karsthuntr

    karsthuntr Caveman

    Messages:
    3,266
    Location:
    Grottoes, Virginia
    You gotta get a feel for it.

    110 plus OA = discharge line temp.

    On a R-22 unit the suction pressure should be close to the OA. (35degs=35psi suction). This will only get you close, you can only tell if its way out of whack.

    Temp rise across coil. This will vary depending on OA.

    Or start selling Rheem, they have a heating chart. :D
  4. ISOTHERMAL

    ISOTHERMAL senior member

    Messages:
    32,288
    Location:
    Green Acres
    Dad taught me that one a long time ago. But your OD coil needs to be free of any ice/frost.
  5. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    Well that's cool. I wish other brands had that.
  6. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    Well at least I have a guideline now, better than none :biggrin:
  7. DPSwitch

    DPSwitch Forget the hearse....

    Messages:
    64,051
    Location:
    Mid-Atlantic
    When I had this problem.... I switched to commercial, cause I never could figure it out.:loltard:


    The WSHP's dont really care if you throw them in cooling mode....... lol
  8. karsthuntr

    karsthuntr Caveman

    Messages:
    3,266
    Location:
    Grottoes, Virginia
    Of course that goes with any checks you make. :D
  9. ISOTHERMAL

    ISOTHERMAL senior member

    Messages:
    32,288
    Location:
    Green Acres
    I remove 13lbs out of a unit last winter, It still had plenty of gas in it to operate:biggrin:. weigh in charge with line set was under 12lbs.

    I would recommend that anytime you adjust the charge of a unit......use scales, that way you know exactly what you put in or took out:thumb:
  10. Swampfox

    Swampfox Trailer Trash

    Messages:
    29,745
    Location:
    Hell Hole Swamp
    both needles straight up, I learned that in tech school :shocked:
  11. DPSwitch

    DPSwitch Forget the hearse....

    Messages:
    64,051
    Location:
    Mid-Atlantic
  12. DPSwitch

    DPSwitch Forget the hearse....

    Messages:
    64,051
    Location:
    Mid-Atlantic
    No wonder you broke the Testo........
  13. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    Not happy with the heating or cooling? just add some refrigerant, charge lotsa $ and run fast :biggrin: Holy crap, that's bad.
  14. ISOTHERMAL

    ISOTHERMAL senior member

    Messages:
    32,288
    Location:
    Green Acres
    lol, I usually take pics of my gauges when I have over charged units (mostly summer time). When my 14yr old boy sees them he will say something like "that'll never work, with todays temp that needle needs to point about to there, and that other ones would probably be pointing to there". Guess I need to teach superheat and subcooling to him. But atleast he knows what a reasonable pressure would be.
  15. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    That's really cool :thumb::thumb: You sure are doing something right, iso
  16. Bender

    Bender Promoted to Regional Turd Polisher

    Messages:
    22,833
    Location:
    Mamby Pamby Land
    Get a tent....check it in cooling....




    :tongue::tongue::tongue:
  17. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    HA no freekin way
  18. DPSwitch

    DPSwitch Forget the hearse....

    Messages:
    64,051
    Location:
    Mid-Atlantic
    Just do what everyone else does.......

    schedule them for spring.....
  19. Andy G

    Andy G riff raff

    Messages:
    11,192
    Location:
    Corvallis, Oregon
    8:22 AM got to the customer's location
    8:31 got out the tent
    10:05 damn tent
    10:25 freekin tent pole went up my ass
    10:40 got the tent pole out of my ass
    11:07 got the tent set up
    11:21 got gauges on it
    12:45 freekin customer's dog got cold, came in the tent and wagged his tail so hard he whapped the wiring and shorted out the controls
    12:50 ok got the wiring fixed, found the breaker and reset it
    1:10 PM customer comes out and asks me how it's going
    1:11 okay about 75 degrees in the tent
    1:12 damn dog humping my leg mo fkr
    1:13 customer's kids come out and ask if they can camp in the tent
    1:30 convinced the customer that the kids need to let me work
    3:00 ok got the temp constant in design parameters
    3:45 got the charge exactly right
    4:00 customer thinks the bill should be $30
  20. karsthuntr

    karsthuntr Caveman

    Messages:
    3,266
    Location:
    Grottoes, Virginia
    Pull out the charge into a clean tank, and weight it back in. On most HP's this will not take long at all (some of the new units with 20lbs of ref. might take awhile), there is no need to vacuum the system down.

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