Help with a water cooled Liebert - Page 2
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  1. #14
    Join Date
    Jun 2012
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    527
    Is it sitting on sacred burial ground of some sort, and have you tried to perform a seance?
    Kidding aside, have you pulled the bulb and put it in hot and cold water yet... just to verify?

  2. #15
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    I would like to know the liquid pressure. What is the difference between discharge pressure and liquid pressure. With just the numbers we have TXV or drier holding liquid back seems most likely, good to high sub cooling and retarded high super heat. The cond is absorbing heat and putting a full column of liquid out but the evap is not getting enough liquid to feed the whole coil. The loss of TD across the evap also supports this as does frosting of distributor tubes. The sudden spike in discharge pressure is odd. If the check valve was being blocked you wouldn't see the pressure spike at your guage since it is down stream of the valve. So I would wanna see the liquid pressure to try and determine where the restriction is, before or after the cond coil.

  3. #16
    Join Date
    Feb 2013
    Location
    OKLAHOMA
    Posts
    60
    I see you have a serious problem..Curious!! Scroll compressor or recip.?? Is this the 1ST compressor change out?? How much oil was/is left in the circuit?? Replaced TXV because it was stuck open or stuck closed??? YIKES!
    Sent from my SCH-R530U using Tapatalk 2

  4. #17
    I understand the concerns about the txv and drier, and that would explain the 'pumpdown' I'm seeing, but it doesn't explain all of the symptoms. Neither does moisture. If it were the filter drier that was clogged, there would more than likely be a temp drop from inlet to outlet; we have no such temp drop. Also, this would not explain the internal bypassing. After doing some research on the design of the compressor, there appears to be a valley of sorts where the discharge pipe and check valve are. It is my belief that there is too much oil in the system, and that after a decent amount of run time, the oil will collect in the tube-in-tube condenser and form a 'plug' that travels to the txv; which in turn is causing our 'pumpdown'. Other times, when the compressor begins bypassing, I believe there is an excess of oil that accumulates in the 'valley' near the discharge check valve which restricts the refrigerant flow. I know the unit holds 34oz of r22, and the compressor has 34oz of oil. If there was any oil left in the system (which I'm sure there was, but the amount that was left is unknown), it would make it a ratio that is greater than 1:1 oil to ref. Does that ratio matter, and if so, why? Is this a conceivable hypothesis? I would really like some feedback on my theory. Here is a cutaway picture of the compressor I am working on.

    Name:  ImageUploadedByTapatalk1363790890.248440.jpg
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  5. #18
    To answer your questions, dobbin, this is a 1 1/2 ton copeland scroll. To the best of my knowledge, this is the first compressor changeout. The owner isn't very forthcoming with info about prior repairs. The unit is approx. 10 years old, and from what I understand, hasn't worked properly in a long time. There was another company that used to service this unit, and they may or may not have been the installing contractor. For all I know, it has never worked properly.

    It may be on a sacred burial ground...or maybe someone died during the install and is now haunting it...lol...

  6. #19
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by Isaac3384 View Post
    I understand the concerns about the txv and drier, and that would explain the 'pumpdown' I'm seeing, but it doesn't explain all of the symptoms. Neither does moisture. If it were the filter drier that was clogged, there would more than likely be a temp drop from inlet to outlet; we have no such temp drop. Also, this would not explain the internal bypassing. After doing some research on the design of the compressor, there appears to be a valley of sorts where the discharge pipe and check valve are. It is my belief that there is too much oil in the system, and that after a decent amount of run time, the oil will collect in the tube-in-tube condenser and form a 'plug' that travels to the txv; which in turn is causing our 'pumpdown'. Other times, when the compressor begins bypassing, I believe there is an excess of oil that accumulates in the 'valley' near the discharge check valve which restricts the refrigerant flow. I know the unit holds 34oz of r22, and the compressor has 34oz of oil. If there was any oil left in the system (which I'm sure there was, but the amount that was left is unknown), it would make it a ratio that is greater than 1:1 oil to ref. Does that ratio matter, and if so, why? Is this a conceivable hypothesis? I would really like some feedback on my theory. Here is a cutaway picture of the compressor I am working on.

    Name:  ImageUploadedByTapatalk1363790890.248440.jpg
Views: 208
Size:  45.9 KB
    Liquid pressure?

  7. #20
    Join Date
    Jun 2012
    Posts
    527
    Excess oil can definitely haunt you. As small as it is I'm sure it does not have a sight glass on the compressor or even a port. Is it too much to pull, drain, and flush?

  8. #21
    Join Date
    Feb 2013
    Location
    OKLAHOMA
    Posts
    60
    I'm just Thinking Out Loud/sharing past experience as my memory suites me.....T.O.L. your inlet H2o temp 60 / outlet 90,,thats a 30 degree T.D., This would acount for the high head..i think h2o condensers were engineered for about a 10 deg. T.D. when everything is installed/working properly.(245#)..I feel like this is way too hi. (Should be close to 210#)For h2o/liquid cooled....Not a proper Flow Of H2o.?? I FEEL LIKE THERE IS AT LEAST 2 PROBLEMS BEING EXPERIENCED HERE! and the one is exacerbating the OTHER PROBLEM..''remember When your up to you're A$$ in alligators that your objective was to drain the swamp

    Sent from my SCH-R530U using Tapatalk 2

  9. #22
    The head pressure control is functioning properly, and there is a sufficient amount of water flow. There is supposed to be approx. 3gpm/ton. Considering we have a 1.5 ton unit, the 7.6 gpm that we are capable of providing is more than sufficient. When the water temp increases, the TD drops, and the head remains the same. I can adjust the head pressure control and get it to a more normal looking head (200#-225#), but we have the same issues.

    Prior to our arrival, the LL gauge port has been removed, so I am unable to obtain those numbers.

  10. #23
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by Isaac3384 View Post
    The head pressure control is functioning properly, and there is a sufficient amount of water flow. There is supposed to be approx. 3gpm/ton. Considering we have a 1.5 ton unit, the 7.6 gpm that we are capable of providing is more than sufficient. When the water temp increases, the TD drops, and the head remains the same. I can adjust the head pressure control and get it to a more normal looking head (200#-225#), but we have the same issues.

    Prior to our arrival, the LL gauge port has been removed, so I am unable to obtain those numbers.
    Ok so we can throw the subcooling out. Could you water regulating valve be hanging up?

  11. #24
    I highly doubt it. Granted, this would cause a high head pressure, but this still doesn't explain the bypassing on a new compressor without it showing up on the gauge port that is only a mere 6" down stream.

  12. #25
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    Quote Originally Posted by Isaac3384 View Post
    I highly doubt it. Granted, this would cause a high head pressure, but this still doesn't explain the bypassing on a new compressor without it showing up on the gauge port that is only a mere 6" down stream.
    You did see it I thought. "It reached 325 before I shut it down". You are assuming 400 is where the compressor will bypass. It may be lower. I don't know what it is either but you could call and ask. Your water regulating valve should modulate to maintain 90-100 SCT and it should be steady. The way it's running up and down it would seem either the flow is changing or you are getting shots of hot water.

  13. #26
    Join Date
    Feb 2011
    Location
    Toronto Ontario
    Posts
    28
    For sure sounds like you got 2 different problems, you say that the unit is rated for 3.5gpm and you are capable of providing 7.6gpm but have you actually put a flow meter across the condenser to check and see what your actually getting? If not, I think that's the first thing you should do to confirm this, also have you tried to acid flush the condenser with descaler I have seen them plenty of times where they begin to get plugged up over time. You did mention that at the beginning you had cleaned some strainers from the pumps. Maybe the dirt had been running throughout the system long before you ever got there.

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