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  1. #1
    Join Date
    Nov 2009
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    Pump down system, solenoid valve


    Hello guys!
    As you may see from my age, I'm pretty new to refrigeration, but I feel that I have a good understanding of the basics

    My question is as following:

    I have mounted a pump down system with two "freezer rooms" (not sure if "freezer rooms" is the right way to say it) at school. I have only runned it a few times.
    I have a Danfoss "EKC 204a" for each room.
    I have programmed -22 degrees celsius, as the setpoint. I know that the solenoid valve will close when I start a "defrost". The thing that I'am not 100% sure about is:

    Does the solenoid valve close when i reach -22 degrees celsius witch is my setpoint?

    Thanks in advance!

    Aleksander



  2. #2
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    Aug 2006
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    england
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    Re: Pump down system, solenoid valve

    If you want to run it on pump down then yes the solenoid should be turned off when the room reaches -22C

    Jon

  3. #3
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    Re: Pump down system, solenoid valve

    Allright!
    Thank you very much

  4. #4
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    Re: Pump down system, solenoid valve

    Thought so, because when I ran the system I observed that when it reached -22C in one of the rooms I heard a "click" and the temperature reached about -22,5C. Then it started increasing all the way up to -18C. when it reached -18C it started dropping down to -22C again.

    Love the feeling off understanding things, and how they work

  5. #5
    Join Date
    Aug 2009
    Location
    england
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    Re: Pump down system, solenoid valve

    Quote Originally Posted by monkey spanners View Post
    If you want to run it on pump down then yes the solenoid should be turned off when the room reaches -22C

    Jon
    true , set the L.P. switch up properly and you .ll be fine

  6. #6
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    Oct 2005
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    IRAN
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    Re: Pump down system, solenoid valve

    Hi there,

    When pumping down the evaporator is starved and the suction pressure goes down so does the evaporating temperature.
    When this happened then your room temperature falls below thermostat setting. The bigger the evaporator the bigger is the temperature difference.
    In one application I had 3C temperature fall when pumping down.

    Cheers
    Even Einstein Asked Questions

  7. #7
    Join Date
    Feb 2010
    Location
    Ireland
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    Re: Pump down system, solenoid valve

    Hi

    yes the valve closes as this is how your system controls it's self at your set point. Once it is reached the valve closes and the system pumps down. It then cuts the compressor out when it pumps down enough to activate the l/p switch. Then once the temp rises enough it opens the valve again it closes the l/p switch which is auto reset and the compressor starts again.


    Stick with it. It's a bad day when u don't learn something new.

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