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  1. #1
    Join Date
    Oct 2002
    Location
    Houston,Texas
    Posts
    167

    Question

    What's the purpose and the proper operation of a electrically operated control valve on a liebert model#UH075A-A00 serial#134384D any input would be much appreciated.Thanks in advance.Hugo

  2. #2
    are you talking about the mixing valve on a chillwater unit or the soleniod for the humidifier pan.

  3. #3
    Join Date
    Oct 2002
    Location
    Houston,Texas
    Posts
    167
    Airworx:This is actually called the suction cutt-off unloader,that is activated by a solenoid,but not really sure how or what the proper sequence of operation is,I do know that is has to do with capacity control,but no sure what or at what point does it unloads or loads up.Any input would be appreciated.

  4. #4
    unloaders help us to overcome low load situations where keeping the system running to maintain humidity or low tempertures will drop the suction pressure below the freeze point like 58 lbs dx and 55 lb chillwater.

    unloaders unload cyliders to keep are suction up.

  5. #5
    Join Date
    Dec 2003
    Location
    Kenilworth New Jersey
    Posts
    230
    If it`s the unloaders you are asking about, They re controlled by the processor. If you have 2 compressors each with one unloader. There is a dip switch setting on the micro that should be set for 4 step cooling. 2 compressor with no unloaders it should be set for 2 step cooling. The micro processor determines how many stages are to be on by how far away from setpoint the room is.

  6. #6
    Join Date
    Nov 2001
    Location
    Seattle, WA
    Posts
    7,817
    Typically it's not an unloader. It's your normal everyday liquid line solenoid valve. Most Lieberts use a pump down method to stop the compressor(s). The LL valve is controlled by the units main microprocessor and has a certain sequence of events.

    What are you trying to attempt that you need to know this info?
    "The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
    - Alexis de Toqueville, 1835

  7. #7
    if the valve is located on the liquid line it is a solenoid valve. it will either drop when the compressor contactor deenergizes or will drop and unit will run till it opens low pressure switch.

    or if its located on the head of the compressor it is a unloader solenoid.

    or if you have no compressor and its located on the chillwater piping it is a 2 or 3 way valve and has an actuator attached to it to control flow.

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