Results 1 to 5 of 5
  1. #1
    Join Date
    Jul 2002
    Posts
    871
    I usually work on larger equip but was wondering if LL lift and friction can have a different effect on a smaller unit than it would have on a lager one. Let's say I've got an AHU 60' away horizontally and 25' up. I think a 10 ton unit would have no problem but what about 1 1/2 ton unit? I know pressure is pressure but what about the percentages?

  2. #2
    Join Date
    Nov 2002
    Location
    emerald city, sc
    Posts
    1,469
    the size of the liquid line has more to do with it, than the size of the unit.
    i wanted to put a picture here

  3. #3
    Those factors are more critical to the suction line than the liquid line, assuming that they are taking the same route, but whatever you are working on you find the Mfrg. literature on it and see what they recommend.

  4. #4
    Join Date
    Apr 2002
    Location
    Dallas, TX
    Posts
    2,987
    Originally posted by incontrol
    I usually work on larger equip but was wondering if LL lift and friction can have a different effect on a smaller unit than it would have on a lager one.
    Liquid line loss due to vertical lift is simply due to the density of the refrigerant. Density in lb/ft3 times lift in feet divided by 144 in2/ft2 gets you pressure loss in psi. For example, R-22 saturated liquid at 100F has a density of 71 lb/ft3. A 10 foot lift gives us 71 * 10 / 144 = 4.9 psi loss. A good rule of thumb to use with most refrigerants is 0.5 psi loss per vertical foot.

    Liquid line loss due to friction is a function of your liquid line size.

  5. #5
    Join Date
    Apr 2004
    Posts
    7,680
    Originally posted by incontrol
    Let's say I've got an AHU 60' away horizontally and 25' up.
    Lets just hope its not a heat pump.

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