Page 1 of 2 12 LastLast
Results 1 to 13 of 15
  1. #1
    Join Date
    Apr 2006
    Location
    Columbus, Ohio
    Posts
    769

    Why do almost all refrigeration sys. use pump down?

    I have a idea of what pump down is for, but why does it seem like on most walk ins, and split system refrigeration systems use pump down? Does it assist in defrosting the coil during the off cycle. I am told that it prevents liquid migration, and allows ease of start up of the compressor. What else does it do?

    Thank You
    J. King

  2. #2
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    165
    It also makes installation easyer by not having to wire a thermostat back to the condensing unit.

  3. #3
    Join Date
    Apr 2001
    Location
    Camel City, NC
    Posts
    6,232

    agreed and

    If the solenoid is wired off the fan circuit and the help turns the fans off to stock the cooler because it's to cold in there, you don't slug the compressor. The system just pumps down.
    Walk-in freezers should be pump down in off cycle and defrost to prevent flood back on start-up.
    Be safe not fast. body parts don't grow back

  4. #4
    Join Date
    Oct 2003
    Location
    las vegas
    Posts
    1,505
    Quote Originally Posted by selfemployed View Post
    If the solenoid is wired off the fan circuit and the help turns the fans off to stock the cooler because it's to cold in there, you don't slug the compressor. The system just pumps down.
    Walk-in freezers should be pump down in off cycle and defrost to prevent flood back on start-up.
    one of the most common reasons for early compressor failure & should
    be against code but never will be.

  5. #5
    Join Date
    Sep 2002
    Posts
    2,718
    To help prevent liquid migration to the compressor,more so with units with head masters that use extra gas. Outdoor units cannot cycle on pressure where the temp gets colder than the cut in.

  6. #6
    Join Date
    Jan 2005
    Location
    where it's nice and warm
    Posts
    255
    In a nut shell, whenever the volume of liquid refrigerant in the system, and the internal volume of the evaporator and suction line assembly exceeds the amount the compressor can safely handle(vaporize and compress),a pump down is needed.

  7. #7
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,510
    It also allows you to run more than 1 indoor circuit off the same condensing unit.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  8. #8
    we should phase out the pump down and utilize inverter and PLC technology
    can anyone go into more detail about the new systems out there now how they vary the frequency of the compressor etc instead of shutting it completely off?

    would this be correct?

    just starting out

  9. #9
    Join Date
    Oct 2011
    Location
    Hull
    Posts
    53
    With a drive who drop in frequency but im not sure its possible with a single compressor unit

  10. #10
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,343
    Quote Originally Posted by Friget_Sparrky View Post
    we should phase out the pump down and utilize inverter and PLC technology
    can anyone go into more detail about the new systems out there now how they vary the frequency of the compressor etc instead of shutting it completely off?

    would this be correct?

    just starting out
    No, pump down is needed in refrigeration because even with variable capacity compressors you still need to shut it down for defrost a couple times a day.

  11. #11
    Quote Originally Posted by craig1 View Post
    No, pump down is needed in refrigeration because even with variable capacity compressors you still need to shut it down for defrost a couple times a day.
    that makes sense

    thanks man

  12. #12
    Join Date
    Sep 2011
    Location
    Plainfield IL
    Posts
    101
    Guys from Texas will claim you dont need a pump down cycle but you do so you dont want to flood out your compressor with liquid freon during the off cycle.

    Also a defrost clock, in my book is a must, for ALL walk in cooler applications. That is if you dont want problems!

    Evan

  13. #13
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,510
    Quote Originally Posted by Fridge Repairer View Post

    Also a defrost clock, in my book is a must, for ALL walk in cooler applications. That is if you dont want problems!

    Evan
    Why? There are other ways to prevent freeze up problems.
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event