Results 1 to 11 of 11
  1. #1
    Join Date
    Jul 2006
    Posts
    96

    Pumping down split-system condensing unit in winter

    Our company has been detailed to remove a split-system condenser from its existing location at the side of the house, and take it around the back, here it will be reinstalled next spring. I would normally pump down the condenser to trap the refrigerant, cut and seal the lines (prior to removal), and disconnect the power. In summer, this would all be quite easy, but we are being asked to do this now, before the new year. Since I have never done this in winter before, I would like to know if it is possible to do without damaging the compressor. I am aware that refrigerant migrates to the compressor in the cold, so it would be full of liquid refrigerant. Would starting the compressor (even for a minute or to) damage it? Would I be better off using a recovery unit instead?

  2. #2
    Join Date
    Nov 2013
    Location
    Windsor, MO
    Posts
    26
    I removed a condenser last week in the same manner by pumping all the refrigerant back to O.D unit. It was a Coleman Unit 15+ years old and it was 12 degree's outside. unit started and pumped down just fine, however this unit was destined for the scrap yard and I wasn't worried about compressor damage. does your unit have a crankcase heater?

  3. #3
    Join Date
    Jun 2013
    Location
    Austin, TX
    Posts
    641
    Use a hair dryer to warm up the compressor if there isn't a crankcase heater. Direct the heat at the bottom and you can start it once it's 20F or so above ambient.

  4. #4
    Join Date
    Feb 2004
    Location
    Ky
    Posts
    269
    Disconnect the outdoor fan motor, that will warm everything up real quick. Then pump it down like you would in the summer.
    LN

  5. #5
    Join Date
    Jun 2013
    Location
    Austin, TX
    Posts
    641
    Quote Originally Posted by larnot View Post
    Disconnect the outdoor fan motor, that will warm everything up real quick. Then pump it down like you would in the summer.
    The whole point is to warm up the compressor before starting it. Having the condenser stay cold actually helps with pumping it down.

  6. #6
    Join Date
    Feb 2004
    Location
    Ky
    Posts
    269
    OK, didn't read everything and I'm in Heatpump territory.

    If the (residential) compressor can't stand ONE out of the ordinary start, in this case to pump it down, and survive, then it has no hope...stick something warm on it for 30 mins and then pump 'er down!
    LN

  7. #7
    Join Date
    Mar 2010
    Location
    Rochester, NY
    Posts
    412
    [QUOTE=ddee;17229341]Our company has been detailed to remove a split-system condenser from its existing location at the side of the house, and take it around the back, here it will be reinstalled next spring. I would normally pump down the condenser to trap the refrigerant, cut and seal the lines (prior to removal), and disconnect the power. In summer, this would all be quite easy, but we are being asked to do this now, before the new year. Since I have never done this in winter before, I would like to know if it is possible to do without damaging the compressor. I am aware that refrigerant migrates to the compressor in the cold, so it would be full of. liquid refrigerant. Would starting the compressor (even for a minute or to) damage it? Would I be better off using a recovery unit instead?[/QUOT

    The refrigerant is already there. Run the heat for 10 min., close your service valves and recover what is left. If you weigh and record the amount you will be really close when you put it back in assuming the line set isn't a lot longer.

  8. #8
    Join Date
    Dec 2007
    Location
    north texas
    Posts
    4
    The oil will be in side... I would disable the out door fan and let it run for a frw mins then do the pump down

  9. #9
    Join Date
    Jul 2006
    Posts
    96
    I pulled the top off the condensing unit, connected the suction side of my guges to the SSV, and closed the LSV. At the same time, I had my helper play a blow drier around the bottom of the compressor while I used my high-temp heat gun on the opposite side and the little receiver tank attached to the compressor. I took a minute to go into the house and jack the heat up to 23C from 16. It took us quite a while to warm the compressor up: it was about 32F ambient, and I got the refrigerant up to about 44F by my gauge. While doing all this, I occasionally pushed in the contactor, and the compressor only hummed, but it finally started, and I ran that sucker down into a slight vacuum before cranking the SSV fully shut. I knew I had succeeded when I cut the lines and no refrigerant came out - not even one tiny "de minimus" puff. I got the power and 24V lines off, we took the brackets off the foundation, and we carried the unit around back and covered it up. Oh, and I also disconnected the 240Vac line from the breaker inside the panel.

    Thanks for the tips - I got 'er done!

  10. #10
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,384
    Don't pump it down. Close the valves. Use your recovery machine to recover the charge in the lineset. 95% of the refrigerant in already in the condenser because it is cold while the lineset and evaporator are warm

    I just did this to a system last week that I know was running with a full charge in the summer. There was only 1/2 LB refrigerant in the 50 ft lineset and evap. The rest had migrated to the condenser on its own

  11. #11
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,619
    I would simply just turn it to cool mode at the thermostat and pump it down .if its a scroll stop at 20 psi if it is a recip let it go to a vacuum,
    We really need change now

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