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  1. #1
    Join Date
    Jul 2010
    Posts
    17

    Confused Trane Chiller Condenser cleanout

    Im curious as to the proper steps i have to take in order to clean out a chiller condenser coil. Apparently the old compressor was "slugging" oil and iv been told it pushed the compressor oils into the condenser coil. no i have to clean out the coil. im also going to be replacing service valves, expansion valve and drier filters prior to connecting the rebuilt 75 ton trane chiller compressor.

    It is a Trane, 75 ton, Air cooled chiller.
    Model CGACD154EFNMM63FGHPRTW

    Prior to the replacement of compressor, it went off on safety 3 times for high head pressure.

    the low oil pressure switch did not trip out.
    and i didnt witness and oil movement in the compressor sight glass.
    When the compressor eventually stopped running, its last reading were -

    117 amp draw. 90PSI suction, 350Head, if im correct.
    the compressor was extreamly hot was well, so i believe it wasnt coming back on the suction side although i had a 90 pressure reading.

    Any takers on steps to clean coil and then possible issues?

  2. #2
    SFTB is offline Bad email address, please contact Admin to fix
    Join Date
    Sep 2011
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    18
    I suspect you have an older unit maybe model e compressor( don't think there made an r or m that big??) judging from the size and being you stated there was an oil pressure switch. Usually oil doesn't hang up in the condenser because liq. refrig will push it to the low side. If oil is in the low side there was a thread about a month ago where someone described loading the compressors to promote the oil return but on a scroll unit. If the system is evacuated then you can blow nitrogen through condenser to check. I don't think it is uncommon for a semi-herm to be hot especially with 350 head. I would make sure coil is clean as far heat transfer. Why the total revamp on the unit if it was only going out on high head? Leaks possibly?

  3. #3
    Join Date
    Jul 2010
    Posts
    17
    There was multiple issue with the unit. The expansion valve was making a terrible hissing sound and causing 15 lb pressure fluctuation on both suction and liquid sides. Added to that the unit was pulling 117 amps and also did have multiple seal leaks. The last time i was there the unit shut down 2 times. I manually reset it and thats when i noticed the incredible heat coming off the compressor. At that point all of a sudden the compressor started to shake as if it was binding and shook the entire condenser. I shut it down, gave it 2 days, wouldnt restart.

  4. #4
    SFTB is offline Bad email address, please contact Admin to fix
    Join Date
    Sep 2011
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    The hissing could have been caused by high condensing pressure. Does the unit have hot gas fed into distrubutor? Compressor jumping could possibly be from loading and unloading. Just a theory... Is it pressure or electrically accuated unloading?

  5. #5
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    4,530
    your model number indicates that this unit is a 150 ton air cooled chiller with 2, 75 ton (each) compressors. 370 psig is the design high pressure cutout. on a 460 VAC application, the RLA is 113 amps...so yeah, you are running pretty hot!

    there are many reasons why a chiller might run with high head pressures.

    1. condenser coil is dirty
    2. condenser fans are not running
    3. condenser fans are not running the correct direction (these compressors can run any electrical phase direction but the fans can not)
    4. non-condensibles in the system
    5. mixed or wrong refrigerant in the system
    6. very high evaporator load (you said 90 psig which is very warm water). this chiller should unload the compressors until the water temperature drops low enough, however, if the unloaders do not work, then you are back to having problems
    7. wrong compressor (if the compressor was replaced improperly with a larger compressor)
    8. too much refrigerant
    9. all of the above or even a small amount of all of the above

    it is possible that the hissing sound was from the compressor (although it is unlikely if your readings are correct). there is an internal relief valve inside the compressor that vents high pressure refrigerant back to the low side of the compressor. this valve is set for 375 psid in this compressor. if your readings are accurate, this probably did not occur.

    slugging oil means too much oil. slugging refrigerant means improper txv adjustment. both break compressors. if you are not tripping on an oil safety, then low oil quantity issues (and possibly slugging refrigerant isssues) are not your biggest concern. during the start up of a compressor, the oil does tend to leave the compressor, however, it will come back with long run times. high head pressure will not cause your oil to hang out in the condenser. it will move through the condenser just fine.

    sounds like you have a mess (and a mystery) on your hands.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  6. #6
    Join Date
    Jul 2010
    Posts
    17
    I installed the new isolation valves today and started wiring the compressor back up. Im going to swap out the filters tomorrow and eventually swap out the expansion valve and solenoid valve. I have a company I deal with send me their main chiller guy. I got the management to give me a budget. I told them I'll have it up in a weeks time givin the issues they have. While this compressor is being serviced, I'm going to have the second compressor looked at which was giving issues as well. Eventually we will get this unit to make the way nice n cold.

    I'll update once I know what full issues are.

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