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Thread: Refrigeration unit issue advice appreciated

  1. #21
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    Just before the distributer and after the expansion valve.

  2. #22
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    Around 34 degrees.

  3. #23
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    Copeland Scroll Compressor. Unit does build a head up to 400 PSI, before I plugged the fans back in. Also, the suction hose is rubber so I pinched it off, unit pulls into a vacuum. But I learned from reading around on there they sometimes have internal relief valves that can sometimes cause issues.

  4. #24
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    That is the reason I pinched off the hot gas line, but as someone pointed out, its possible some is still getting by.

  5. #25
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    System:
    Morgue unit
    230V single-phase Copeland scroll
    externally equalized TXV
    CPR valve set to 35 psi (2 F.)
    404a refrigerant

    Operating:
    Condenser air in - 100
    Condenser air out- Will need to check, unit does have a sight glass just after the drier and I can see liquid in the SG.
    Suction pressure - 35 (2 F.)
    Discharge pressure - 275 (111 F.)
    Evaporator air in - 104 degrees
    Evaporator air out - 104 degrees

    If liquid or suction is valved off - will the compressor pump down to 5-10 lbs? Yes, to a vacuum.

    This system has a CPR to prevent excessive pull-down amps. Hot gas is used only in defrost, I'm told that is why the CPR is needed for excessive suction pressure is defrost cycle to protect the compressor.
    What is the model number of the CPR? Danfoss KVL15

    Are we Positive that the CPR is not an EPR? Fairly sure.

    What is the model number of the TXV? Does it have a Z in the model number? TXV emerson 802460

    This system also has Hot Gas Bypass - to maintain low load suction pressure? Yes? For defrost.
    If so; where exactly does the hot gas enter the low pressure portion of the system? Just before the evaporator distributor.
    What is the HGBP valve set point? Uses electric solenoid one at the condenser one at the evaporator and the controller switches them to activate defrost based on evaporator temperature.
    During system pull down is the vapor line after the /HGBP warmer than ambient? Will need to check.

    What is the compressor model number? ZB21KCE-PFV-240
    What is the compressor Full Load Amp rating? If am looking at the label correctly, looks like 20.80.
    What are the actual compressor operating amps? Will need to check that as well. I am working on something else at the moment, but i'll get this information when able.

    Domestic morgue Unit is typically not a freezer and would not typically have a low temperature compressor. CPR set to 35 lbs. / 2 seems very odd at best. I would set to CPR to FLA during warm pull-down. Also valve off HGBP. If no HGBP service valve: use a auto radiator hose pinch tool on the refrigerant hose.

    Two TXV's in a row are extremely unlikely to both be defective. <g> I agree.

    The thing that stood out to me is the high suction pressure before the CPR with the compressor running, hot gas pinched off 210 on the suction 275 on the discharge, its like we don't have an expansion valve at all.

  6. #26
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    What's the trailer size ?

  7. #27
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    Poodle Head Mikey is offline Membership Chair/ARP Committee / Professional Member*
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    Thanks.

    Morgue unit
    Copeland - ZB21KCE-PFV-240 - Medium temp. / 20 amps max (22K @ 20 suction / 32K @ 45 suction)
    Emerson TXV # 802460
    CPR - Danfoss KVL15
    System charge - R-404

    CPR valve set to should initially be set for 75 lbs. & then verified against compressor amp draw for final setting.

    Operating:
    Condenser air in - 100
    Condenser air out - ?
    Evaporator pressure - 210 lbs. (110 degrees F.)
    Compressor Suction pressure - 35 lbs. (2 degrees F.)
    Discharge pressure - 275 (111 F.)
    Evaporator air in - 104 degrees
    Evaporator air out - 104 degrees

    Compressor pumps down to vacuum.

    So there is no HGBP - it is a Hot Gas Defrost system.

    What evaporator set point initiates the defrost? Or is Defrost initiated with a defrost-timer?

    During system pull down is the vapor line after the /HGBP warmer than ambient? Will need to check.

    What are the actual compressor operating amps?

    =============

    In very basic terms; high evaporator pressure means that too much refrigerant is entering or too little refrigerant is leaving. <g>

    210 lbs is 92 degree evaporating temperature. The compressor suction pressure needs to be held to <90 lbs. - so that is going to be a longish hot pulldown. <g>

    What happens if you just leave the system running for 24 hours?
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  8. #28
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    Quote Originally Posted by VTP99 View Post
    What's the trailer size ?
    16 foot enclosed box, with spray foam insulated walls.

  9. #29
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    What is the compressor amp draw?

    Sent from my SM-G892A using Tapatalk

  10. #30
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    Adjust the CPR to control the comp amps to its max allowable setting, even if the press is running at 50psi.

  11. #31
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    210PSIG at the outlet of your evap is definitely a problem haha. Sounds like it's running straight through your TXV with no metering at all. Or your valves are shot which I doubt since you said you were able to get the TXV to throttle to 80PSIG. I would be making sure thT is the correct TXV. .

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