Page 1 of 2 12 LastLast
Results 1 to 13 of 15
  1. #1
    Join Date
    Jul 2008
    Posts
    5

    Help! 20-ton Trane liquid line pressure loss

    I am trying to start up a 20-ton straight cool condenser sitting on the ground. The heat exchanger is 3 stories up (125 ft line set and 5/8 liquid line). The unit has thermostatic expansion valve. The liquid line at the condenser is 255 psi and the liquid line at the heat exchanger is 205 psi. What could be causing the pressure loss? There is no filter.

  2. #2
    Join Date
    Nov 2003
    Location
    Rochester, New York
    Posts
    392
    The 3 story run of the liquid line??

  3. #3
    Join Date
    Nov 2003
    Location
    Boston
    Posts
    600
    5/8 liquid line at 125 ft of linear run is too small for R22.

    What is your equivocal length?
    Edited by powerhead on more than one occasion

  4. #4
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,586
    You need to look at the install manual and make sure you follow the long line guidelnes. You can also get a hold of the manufacturer either at your local sales office or the factory technical guys. You should make a drawing of what you have, get a fitting count and note if the 90's are long radius or not.

    You will probably be required to have several accessoires, such as an inverted trap at the top of the suction line, a hard start kit, hard shut off txv, crank case heater. You may find out you have exceeded the capabilities of the system. They typically don't want you upsizing the liquid line.

    The pressure drop is due to the length of the line. Inevitably when you have along run your system capacity is reduced and it's worse when you pump liquid uphill. Probably from 3-5%.

    Talk to the manufacturer and Good luck!

  5. #5
    Join Date
    Mar 2005
    Posts
    665
    perfect light commercial application for liquid pressure amplification (hy|save ), pump the liquid over/up high lift and possibly float head pressures saving energy , regards stan
    Keep it simple to keep it cool!

  6. #6
    Join Date
    Jul 2008
    Posts
    5
    Thanks. The liquid line length isn't negotiable. The freon is R407C not R22. I didn't mention this before. I also did more checking today and I got a 9 degree subcool at the condenser. Any more suggestions?
    For Stan, I don't know what you mean by your response, could you provide some additional details?

  7. #7
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,656
    Quote Originally Posted by stanbyyourword View Post
    perfect light commercial application for liquid pressure amplification (hy|save ), pump the liquid over/up high lift and possibly float head pressures saving energy , regards stan

    Great energy saver and it should help with the liquid drop.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  8. #8
    Join Date
    Jul 2008
    Posts
    5
    I didn't get what Stan was saying in his reply. Could you provide more information on this?

  9. #9
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,525
    Quote Originally Posted by tracdan View Post
    Thanks. The liquid line length isn't negotiable....
    it will be negotiable if the unit can not work properly or is too maintenance intensive or the failure rate becomes too high.

    how much steam do you lose when you run up 3 stories...pressure drop is going to be the same...when you run it uphill, it loses pressure. your pressure drop may be normal, but is it acceptable?

    too small of a liquid line and you have large pressure drops...too large of a line and you hold too much refrigerant and oil. you need a happy medium and that may mean relocating the unit.

    like Pneuma said, get the local office involved and get them to bless it with Trane's holy water that way you are covered.

    good luck.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  10. #10
    Join Date
    Oct 2007
    Location
    Arizona DUH
    Posts
    174
    What model Condensing unit is it? Is it a scroll compressor?

  11. #11
    Join Date
    Jul 2008
    Posts
    5
    It's a dual scroll compressor. I will check the exact model today.

  12. #12
    Join Date
    Mar 2005
    Posts
    665
    http://www.hysave.com/technology/ref...t_pumping.html lots of info here and contact, hysave pumps are a refrigerant liquid delivery pump, used primarely in refrigeration as pressure subcoolers and floating head pressure technology whilst supplying 100% column of liquid to txv over long runs, i will try to post a pic of a large condensor on the ground with no NPSH /gravity to feed the pump , what is used in this app. is an inverted "dropleg" oversized usually at 2" x 24" high to maintain gravity /column to inlet , and away you go regards stan
    Keep it simple to keep it cool!

  13. #13
    Join Date
    Mar 2005
    Posts
    665
    Keep it simple to keep it cool!

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