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  1. #1
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    To pump down or not to pumpdown

    Went on an old W/I Cooler turned the timer to defrost setting I expected for it to pumpdown and cut off but it just cut off immediately went and turned the testator up same thing immediately cut off this is a 3 phase unit 7 hp 3 Evaporator coils can this hurt any thing due to it being 3 phase and does not require any start kits.?

  2. #2
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    Pump down is preferable but not needed!

  3. #3
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    Aug 2013
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    Pump down has nothing to with being 3 phase or any electrical configuration.

    Pump down is a compressor protection feature. If this condensing unit is located outside it's extremely needed.

    Quite honestly on a system that size it's stupid to not have it pump down. 7hp and 3 evaporators? No doubt the charge is over 15 or even 20lbs.
    All it takes is one time for enough refrigerant to flow into the evaps on the off cycle to potentially cause a flooded start.

    I would be converting that system to pump down if I were on that system

    Sent from my SM-G975U using Tapatalk

  4. #4
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    Jul 2000
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    I agree with UmmScott that it should have pumpdown control, especially if the condensing unit is located outdoors.

    If you do make it a pumpdown system, I would suggest replacing the original low pressure switch which has been sitting there for all these years getting no exercise. I wouldn't trust it. If it fails, the compressor will run in a vacuum during every defrost and off-cycle. Not good.

  5. #5
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    Nov 2006
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    Say Ice.... what is your recommended pressure switch to be used for that pump down configuration?

    I see a lot of repairs using capsule switches (which always makes me crazy) but there's a couple different brands of settable switches, and I'm just curious which one you would typically recommend.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
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  6. #6
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    Quote Originally Posted by timebuilder View Post
    Say Ice.... what is your recommended pressure switch to be used for that pump down configuration?

    I see a lot of repairs using capsule switches (which always makes me crazy) but there's a couple different brands of settable switches, and I'm just curious which one you would typically recommend.
    Of the brands that I'm familiar with... Penn/Johnson Controls, Ranco, Emerson and Danfoss...I have always preferred Penn, however none made today have the reliability of those from made before we heard that "giant sucking sound" of jobs and manufacturing leaving the US.... (RIP H Ross Perot).

  7. #7
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    I agree that the United States typically made the best parts and equipment on the planet.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

    AOP Forum Rules:







  8. #8
    Join Date
    Jun 2018
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    Bay saint louis ms
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    Thread Starter
    I will rewire it’s a simple circuit just have to pull the rat nest of wires out that s accumulated over 30 years ! Man they have green wires up in that box box that I know are hot just by glancing in there ��!


    M

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  10. #9
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    Jan 2019
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    Hi, I am posting for the first time here, but I have been following this forum for a while.

    Quote Originally Posted by UmmScott View Post
    Pump down is a compressor protection feature. If this condensing unit is located outside it's extremely needed.
    Quote Originally Posted by icemeister View Post
    I agree with UmmScott that it should have pumpdown control, especially if the condensing unit is located outdoors.
    Could some of you guys elaborate this a bit? Why is this more important when the unit is outside?

    Thanks.

  11. #10
    Join Date
    Jun 2006
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    Refrigerant will migrate to the coldest spot. If the condensing unit is outdoors, and it is colder outdoors than the refrigerated space, the refrigerant will tend to migrate to the compressor, mixing with the oil, causing a flooded start up.

  12. #11
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    Thread Starter
    Bob what they are saying if the compressor starts or trys to start with liquid Freon on top of the piston it will break or bend a rod just like a marine engine with water on top of the piston!

  13. #12
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    Thank you, now I get it!

  14. #13
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    Quote Originally Posted by icemeister View Post
    Of the brands that I'm familiar with... Penn/Johnson Controls, Ranco, Emerson and Danfoss...I have always preferred Penn, however none made today have the reliability of those from made before we heard that "giant sucking sound" of jobs and manufacturing leaving the US.... (RIP H Ross Perot).
    Not a fan of Danfoss controls. We sell all the brands mentioned and probably sell Penn/Johnson at a 100/1 ratio to the other brands. When I was still in the field, I preferred Ranco because they were easier to set up the cut in/out points.

    It's important to not mount the captube in a downward position. If oil to gets into the captube the controls will act funky
    Officially, Down for the count

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