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  1. #1
    Join Date
    May 2006
    Posts
    4
    Comfortmaker heat pump; standard 300/150 hi/lo factory settings; R22 - 5.5lb charge

    Current pressures: 300/90. I have cleaned condenser and evap coils thoroughly. Both fans working fine. Good air flow through evaporator and condenser. There are no leaks, and no icing. I have tried adjusting the charge to raise the low side pressure, but in doing so would also raise the high side exponentially. (i.e. Increase the suction pressure by 20 psi, and the head pressure would jump as much as 150 psi)

    I've never ran into a problem of this particular nature where the usual suspects have all been ruled out and the problem still exists. If I had to pick something to try next, I guess I would have to start looking at the compressor. This is an older unit, probably 15 years old, and I'm not sure what to try next. Any ideas or advice regarding this problem would be greatly appreciated.

    Thanks.

  2. #2
    Join Date
    Oct 2003
    Location
    Valdosta Ga
    Posts
    847
    what is the low side pressure suppose to be

  3. #3
    Join Date
    Mar 2006
    Location
    Albany NY
    Posts
    91
    Might be a restriction...

    Check your dryer, lineset, metering devices and check valves.

  4. #4
    Join Date
    Mar 2006
    Location
    Albany NY
    Posts
    91
    Then again w/ those pressures you might be a little overcharged too.

  5. #5
    Join Date
    May 2006
    Posts
    26
    You cant just dump R-22 in the system and look at the pressures to adjust the charge. There are many variables that are used to charge a unit.
    I would suggest calling an HVAC contractor to properly charge your unit. Simply dumping R-22 in ( if thats what you used) and trying to get the pressures to match will destroy your airconditioner and possible cause you injury and or property damage.
    We cant give step by step instructions to help you. Sorry

  6. #6
    Join Date
    Jan 2006
    Location
    Near Atlanta, GA.
    Posts
    14,631
    Define low suction

  7. #7
    Join Date
    May 2006
    Posts
    4
    The unit is designed for operating pressures of 150 PSIG on the suction side. Currently the suction pressure is at about 90 PSI.

    The discharge pressure is designed to run at 300 PSI. Currently the unit is running at 300 PSI on the discharge side.

    I didn't want step by step instructions. I was educated and certified in refrigeration by EPA reps through the D.O.D several years ago, so I can reclaim/charge etc legally. But it's been a while since I've had to troubleshoot a heat pump (They're a lot different than the giant diesel driven systems used in the airline industry where the majority of my experience was garnered), and I don't have an R22 reclaimer unit anymore, so just wanted to check all possibilities before I have to rent one or call a tech or whatever.

    A restriction might be the best logical explanation, but I just wanted to get some opinions before I decided to check for that and/or the compressor.


    I suppose overcharge is also a possibility, but with the pressures being so disproportionate at this point, I don't want to mess with the charge too much.

    Any comments are appreciated.

    Thanks
















  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    Those numbers 300/150 are not recommended pressures. They are merely ratings for constant pressure limits. 90 is too high but the unit is probably well overcharged as it is.

    You may want to have a contractor look at it.

    As you can see, the EPA test is a refrigerant handling test, not a test of skill. Its a test of dates and laws.

  9. #9
    Join Date
    Sep 2004
    Location
    Portage
    Posts
    909
    hillio The unit is designed for operating pressures of 150 PSIG on the suction side. Currently the suction pressure is at about 90 PSI.

    The discharge pressure is designed to run at 300 PSI. Currently the unit is running at 300 PSI on the discharge side.

    I didn't want step by step instructions. I was educated and certified in refrigeration by EPA reps through the D.O.D several years ago, so I can reclaim/charge etc legally. But it's been a while since I've had to troubleshoot a heat pump (They're a lot different than the giant diesel driven systems used in the airline industry where the majority of my experience was garnered), and I don't have an R22 reclaimer unit anymore, so just wanted to check all possibilities before I have to rent one or call a tech or whatever.

    A restriction might be the best logical explanation, but I just wanted to get some opinions before I decided to check for that and/or the compressor.


    I suppose overcharge is also a possibility, but with the pressures being so disproportionate at this point, I don't want to mess with the charge too much.

    Any comments are appreciated.

    Thanks
    ------------------------------------------------------------

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  10. #10
    Join Date
    May 2006
    Posts
    4
    *Quote* Those numbers 300/150 are not recommended pressures. They are merely ratings for constant pressure limits. 90 is too high but the unit is probably well overcharged as it is.

    You may want to have a contractor look at it.

    As you can see, the EPA test is a refrigerant handling test, not a test of skill. Its a test of dates and laws. *End Quote*

    No. The constant pressure ratings for this unit are 450 and 350 PSI respectively. The recommended OPERATING pressure settings from the manufactureer are 300 and 150. I know these settings are much higher than most of you are used to seeing on a typical heat pump, but thats just the way it is. The low pressure cutout is permanently set at 75 PSI, so I can't go much lower than the 90 that I have now. The high pressure cutout is permanently set at 450 PSI, not that I would ever let it get that high.

    Also, the superheat is at about 16 degrees, which if memory serves me right is within acceptable limits. So that's just another thing thing that doesn't add up.


    And for those who were wondering, I will clarify things a bit. Along with the EPA cert exams, I have also passed the licensing exams in VA, NC, FL and GA as well as the much tougher DOD aviation electrical/HVAC exams, so I do have a good bit of refrigeration knowlege. It's just that I haven't had to use it in so long that it is taking me a while to refresh my memory on some of this stuff. I'm capable of repairing the unit once I determine for certain what is causing the problem.

    Thanks again.

  11. #11
    Join Date
    Apr 2004
    Posts
    7,680
    I assumed R-22. If you are using an alternate refrigerant such as R410A then you would be doing yourself a favor by posting the refrigerant type.

  12. #12
    Join Date
    Oct 2004
    Posts
    3,400
    Originally posted by docholiday
    I assumed R-22. If you are using an alternate refrigerant such as R410A then you would be doing yourself a favor by posting the refrigerant type.
    Doc, he stated R-22 in his original post.

    I think he's trying to get it to run at TEST pressures.
    If he gets it to 150 psig, he will have an 82 degree saturation point in the evaporator.

    It's already running about 90 psig/54 degrees, and he wants to ADD gas.

    He's a smart guy, but I think he's missing something somewhere.

    Maybe he's trying to run it in cooling mode, using heating pressures?

    [Edited by Wild Leg on 05-31-2006 at 12:10 PM]

  13. #13
    Join Date
    Oct 2003
    Location
    Valdosta Ga
    Posts
    847
    what is the model number condensor and evaporator please

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