Page 1 of 9 12345678 ... LastLast
Results 1 to 13 of 116
  1. #1
    Join Date
    Oct 2007
    Location
    ATLANTA
    Posts
    120

    Charging walk in coolers and freezers

    Hi,

    I worked with a tech recently who when charging walk in coolers and freezers after compressor change outs. He would cut off the condenser fans for brief periods of time. Both R-22 and 404-A.

    Im just curious at what this was accomplishing and do any of you guys also do this and why? And how is this done properly etc...

    Another thing say you are charging an R22 refrigeration system (large pan cooler) which requires 34 pounds of R-22. I had a heck of a time getting that much charged in. I ran warm water over the container many times to get the pressure back up to charge in the vapor.

    Any tricks out there at speeding this process up? I know that charging liquid is considered a no no and the little liquid charge restrictor device is pretty slow as well.


    Thanks

  2. #2
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,449
    Quote Originally Posted by AtoZhvac View Post

    Any tricks out there at speeding this process up? I know that charging liquid is considered a no no and the little liquid charge restrictor device is pretty slow as well.


    Thanks
    If the system has the right valves in the right places, you can close the receiver outlet and charge liquid into the liquid line. The liquid will then flow through the evap and return to the compressor as a gas. A few weeks ago I used this method to put 92 LBS into a system in about 15 minutes.

  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    Depending on the type of compressor, I charge liquid into the suction line.

    With refrigerant cooled compressors, it takes a heck of a lot of liquid to cause any damage. You have to monitor the charging, but you should be anyway.

    Charging vapor in quantities much over a pound or two is a huge waste of time.

    If the unit has a headmaster, there is a very specific charging procedure outlined in Sporlan's bulletin 90-30-1

    As far as shutting down the condenser fans, that makes exactly NO sense.

  4. #4
    Join Date
    Jan 2007
    Location
    maine
    Posts
    788
    Quote Originally Posted by jpsmith1cm View Post
    Depending on the type of compressor, I charge liquid into the suction line.

    With refrigerant cooled compressors, it takes a heck of a lot of liquid to cause any damage. You have to monitor the charging, but you should be anyway.

    Charging vapor in quantities much over a pound or two is a huge waste of time.

    If the unit has a headmaster, there is a very specific charging procedure outlined in Sporlan's bulletin 90-30-1

    As far as shutting down the condenser fans, that makes exactly NO sense.
    He might be doing thatt to get the head pressure up to clear the glass... I have a few systems that, is the charging procedure for those walk-ins. Makes no sense to me to raise the head then clear the glass on a system with head master.. but what ever..

    As far as liquid charging i charge all my systems with liquid into the suction, you just need to be carfull not to put to much in to fast. I charge 10 psi above what the system is running with liquid

  5. #5
    Join Date
    Jul 2009
    Location
    Houston,Tx via Wilmington,NC
    Posts
    59
    Don't you have to charge R-404 as a liquid?? I can't see any need to cut off condenser fans.

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    Quote Originally Posted by TxDusty View Post
    Don't you have to charge R-404 as a liquid?? I can't see any need to cut off condenser fans.
    You have to remove it from the cylinder as a liquid, yes.

  7. #7
    Join Date
    Oct 2007
    Location
    ATLANTA
    Posts
    120
    Quote Originally Posted by yotaman16 View Post
    He might be doing thatt to get the head pressure up to clear the glass... I have a few systems that, is the charging procedure for those walk-ins. Makes no sense to me to raise the head then clear the glass on a system with head master.. but what ever..

    As far as liquid charging i charge all my systems with liquid into the suction, you just need to be carfull not to put to much in to fast. I charge 10 psi above what the system is running with liquid

    Thanks for the reply.
    Im trying to understand all of this, you say that you have some systems that use such a procedure.
    If cutting the fans off to clear the glass then what about getting the glass clear under normal conditions with the fans on? Im not understanding what turning the fans off does except temporarily raising the head pressure.

    Yes both of these systems that I observed this done on did have head masters so was it a useless procedure?

    Thanks

  8. #8
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    http://sporlan.jandrewschoen.com/90-30-1.pdf

    There is the link for charging with headmaster valves.

    Raising the head pressure while charging is a waste of time, really. Yes, it will clear the sightglass, but it won't speed charging in any way.

    Follow 90-30-1 and walk away.

  9. #9
    Join Date
    Oct 2007
    Location
    ATLANTA
    Posts
    120
    Quote Originally Posted by jpsmith1cm View Post
    http://sporlan.jandrewschoen.com/90-30-1.pdf

    There is the link for charging with headmaster valves.

    Raising the head pressure while charging is a waste of time, really. Yes, it will clear the sightglass, but it won't speed charging in any way.

    Follow 90-30-1 and walk away.

    Hi

    I have studied the Sporlan link and ever determining the amount of unloading that is going on would be a confusing and an uncertain thing to ever know exactly.

    Most of what I work on which does have head pressure controls is walk in coolers and ice machines etc which do not have unloaders and the best info that I can gain from the Sporlan literature is to watch the sight glass while charging and that seems to be accurate at any temperature even at low outside ambients is that correct?

    I dont understand this statement below from the Sporlan instructions.

    "The extra refrigerant charge for head pressure control
    should be weighed in now by admitting liquid refrigerant
    to the high side."

    My question is this. The statement occurs after head pressure would be above the pressure in the refrigerant tank so how are you able to admit liquid refrigerant into the high side? I can only assume that the system was supposed to be shut off to add the liquid to the high side?

    Thanks

  10. #10
    Join Date
    Jul 2006
    Location
    NorthWest
    Posts
    147
    Front seat the receiver king valve and let the compressor suck from the refrigerant tank.

  11. #11
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    Quote Originally Posted by thethomas4 View Post
    Front seat the receiver king valve and let the compressor suck from the refrigerant tank.
    Most units you can just meter the refrigerant into the suction line.

    No problem.

  12. #12
    Join Date
    Jul 2006
    Location
    NorthWest
    Posts
    147
    Quote Originally Posted by jpsmith1cm View Post
    Most units you can just meter the refrigerant into the suction line.

    No problem.
    That is what I'd normally do in this situation unless its a rack and I was using
    HCFCs (Mp39, hp80, 408a) or 404a,507. these will not indicate a rise in receiver
    level for a few hours.

  13. #13
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,967
    Quote Originally Posted by AtoZhvac View Post
    Hi

    I have studied the Sporlan link and ever determining the amount of unloading that is going on would be a confusing and an uncertain thing to ever know exactly.

    Most of what I work on which does have head pressure controls is walk in coolers and ice machines etc which do not have unloaders and the best info that I can gain from the Sporlan literature is to watch the sight glass while charging and that seems to be accurate at any temperature even at low outside ambients is that correct?

    I dont understand this statement below from the Sporlan instructions.

    "The extra refrigerant charge for head pressure control
    should be weighed in now by admitting liquid refrigerant
    to the high side."

    My question is this. The statement occurs after head pressure would be above the pressure in the refrigerant tank so how are you able to admit liquid refrigerant into the high side? I can only assume that the system was supposed to be shut off to add the liquid to the high side?

    Thanks
    Pretty much just posting here so I get e-mail alerts when someone answers this question. I'm guessing it may be by closing the inlet service valve to the receiver and as system goes into pump-down the pressure drops in the receiver which allows you to add refrigerant?

Page 1 of 9 12345678 ... 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