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Thread: Mcquay

  1. #1
    seamus Guest
    I Have A wdc 087 I Think its a dual. Where is a warning alarm saying "Low Evap Pres NO LOAD" This machine has been doing this since it was new the machine is way over sized flow ok, pressure drops ok. I set min comp amps to 30% from 40% anything else I can Do Does anyone have Service Lit on these All I have IOM's
    Thanks In advance

  2. #2
    Join Date
    Mar 2004
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    You have various things that may cause this low pressure condition in my opinion. Some are simple some are not as you likely know.

    Conditions at the time of the alarm will help determine the problem. I noted you lowered the minimum amps setting. Is this happening at light loads?

    Verify the accuracy of the pressure transducer or transducers.

    Check the setting for this alarm and verify it is correct.

    You seem to believe that you do not have a water flow issue, make sure that is not a problem.

    Is the chilled water setpoint in line with the setting for the refrigerant settings?

    Is the leaving chilled water temperature probe accurate?

    You may have a refrigerant feed issue. At what load is the problem being logged to the buffer? What are the readings from either the alarm buffer and or the trend log when this is happening? What is the condenser water temperature?

    Don't trust any of the pressure readings until you verify them with an accurate gauge. In fact verify all readings for temp and pressure on all units.

    Hope this gives you some ideas.

    Good luck.

  3. #3
    Join Date
    Mar 2004
    Post Likes
    Is this unit still under warranty? What does the start up sheet say about the load at time of start up? I don't think I would go into the service settings and change them to get this warning to clear. Is more load going to be added to this unit in the future? Like Lew2 said, check your sensors and transducers for accuracy and then go from there. This unit should be able to run at 5% of design load (one compressor @min. capacity).

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