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  1. #14
    Join Date
    Jul 2011
    Location
    Nanaimo,BC, Canada!
    Posts
    346
    A pump down test is a great place to start!!! And yes if there is any kind if valve issue, or leaking internal pressure relief valve. The pressures will balance almost immediately depending on the issue. And fwiw copeland typically does recommend head cooling fans on their compressor for low temp applications especially on R22

  2. #15
    Join Date
    Jul 2011
    Location
    Nanaimo,BC, Canada!
    Posts
    346
    Oh yeah and remember to shut iff the return line from the oil separator during pump down test!!!

  3. #16
    Join Date
    Jul 2009
    Location
    Connectitaxed
    Posts
    2,644
    HGV was replaced as suspect of the issue. Now you have a worse situation. How did you dertemine that the HGV was leaking thru? Do you still have the same issue? Possible bad replacement. Do a pump-down as suggested to check the compressor.

  4. #17
    Join Date
    Nov 2009
    Location
    Richmond, working under tarps
    Posts
    495
    report the efficiency test numbers and we'll go from there.

    Hope the HGV has the 'arrow' in the right direction, I know it probably is but its worth a double check.

    Is the SG full? Refrigerant charge ~50lbs?

    Cause 170 head seems low for this application,,,,,,,I usally set the water reg to 225-235 during freeze cycle.

  5. #18
    Join Date
    Sep 2011
    Location
    Central Ohio
    Posts
    8
    "HGV was replaced as suspect of the issue."

    No, HGV was replaced because it was worn out internally and sometimes wouldn't close properly. This problem didn't exist prior to the change out of the HGV.

    "Hope the HGV has the 'arrow' in the right direction, I know it probably is but its worth a double check.

    Is the SG full? Refrigerant charge ~50lbs?

    Cause 170 head seems low for this application,,,,,,,I usally set the water reg to 225-235 during freeze cycle."


    Yep, the HGV has the "arrow" in the right direction. That was one of the first things we checked, we aren't angels. Made a few mistakes over the years, probably will make some more before I'm gone.

    Site glass is full. System holds 117lbs R22. We weighed it in after repairs.

    This system normally runs at 35lbs suction, 215 head. This why I'm so confused--only 170 lbs head but 300+ degrees on cylinder heads. Normal is 200 to 210 degrees.

    We did not go back to this job today, had some other emergency work, so pump down tests, etc will have to wait 'til tomorrow. I have really enjoyed the responses to the problem and they all have given more food for thought. As a matter of fact now I am wondering if something has happened to the TXV and it might be drastically underfeeding. Copeland really depends on cool suction gas to help cool these compressors in this application.

    It just seems strange to have all this happen when the unit was not running and shut down for repairs.

    I will let everyone know what the outcome is.

  6. #19
    Join Date
    Jul 2011
    Location
    Nanaimo,BC, Canada!
    Posts
    346
    You say normal operating pressures are 35/215, with approx 220 ish head temp right!! But you're getting 40/170 and can't runt it for very long. Sounds like the comp is recycling it's discharge gas for some reason, 40 psi suction is only 5 psi high from normal. I'd pull the heads off one more time, and carefully with your screw driver or some other tool actuate the pistons as if it were running and see if all move as they should, I'm suspecting either a broken connecting rod, or a leaking internal
    Pressure relief. I don't think its anything external to the compressor. When you charged it it ran fine long enough to fill the sight glass right??? So something during the charging process has failed! Did you charge through the suction or the liquid??? As a vapour or liquid???

    Just some thoughts! Good luck

  7. #20
    Join Date
    Nov 2009
    Location
    Richmond, working under tarps
    Posts
    495
    Quote Originally Posted by Sprinter105 View Post
    .I will let everyone know what the outcome is.
    anything new?

  8. #21
    Visual inspection of the valve plate cant always show as a problem. I bet @ $1600 a valve plate is still MUCH cheaper than compressor rebuild again.

    Do you have a remote condenser? Ambient temps? Is liquid line hot? Almost sounds like your head pressure control is bypassing or stuck but LL should be hot & sight glass probably showing short unless its stuck partially open. Spray cold water onto cond coil & see if that cools receiver (if its hot). If it is than you found problem.

    Gl
    ed

  9. #22
    Join Date
    Jul 2009
    Location
    Northern area between Alantic and Pacific
    Posts
    107
    I never work on a compressor like this, But I think the problem is internal. Something insdie not working properly,like piston has friction with the wall and generates heat;doesn't have enough suction or discharge capacity. that might explain why it has high heat,high suction and low discharge pressure.

  10. #23
    Join Date
    Mar 2001
    Posts
    1,491
    TXV underfeeding?
    One way to outthink people is to make them think you think. They'll think you're not really thinking what you're trying to get them to think you think...........

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