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  1. #1
    Join Date
    Feb 2010
    Location
    Indianapolis, Indiana
    Posts
    34

    Confused Carrier guidelines for vertical risers?

    Hey guys,

    I am installing three Carrier 24ABS condensing units in a hotel. This is a new installation. I think that I need to either increase the suction line size or put traps in it to ensure oil return to the compressor. The condensers are on the roof about 22 feet above the air handlers. I can't find any guidelines for this in the installation manual nor on Carrier's website. Any suggestions? The systems are 3 ton, 2.5 ton and 1.5 ton. The linesets will have about 30 feet of horizontal run.

    Thanks.

  2. #2
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,929
    Quote Originally Posted by cholden324 View Post
    Hey guys,

    I am installing three Carrier 24ABS condensing units in a hotel. This is a new installation. I think that I need to either increase the suction line size or put traps in it to ensure oil return to the compressor. The condensers are on the roof about 22 feet above the air handlers. I can't find any guidelines for this in the installation manual nor on Carrier's website. Any suggestions? The systems are 3 ton, 2.5 ton and 1.5 ton. The linesets will have about 30 feet of horizontal run.

    Thanks.
    page 9, figure 4.

    http://www.xpedio.carrier.com/idc/gr...t/llgp-2xa.pdf

  3. #3
    Join Date
    Feb 2010
    Location
    Indianapolis, Indiana
    Posts
    34

    Hmm

    Thanks for the link. I looked at the manual but I could not find any information on trapping the suction line. Also, these are R-22 units with scroll compressors. I am very hesitant to install a lineset without suction traps because I am worried about oil return. I have looked at all the carrier manuals that I can find but none of them say anything about trapping a vertical suction line. Am I just way off thinking that there will be a lubrication problem?

  4. #4
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,929
    I got this from goodman:
    NOTE: When the outdoor unit is located above the indoor coil, the maximum vertical rise
    must not exceed 25 feet. If the maximum vertical rise exceeds 25 feet, premature
    compressor failure will occur due to inadequate oil return.

    Sent carrier an e-mail to see if they have a technical assistance line. I pay hell on their website's search engion getting specific information. Your model number didn't even come up as valid until several attempts at getting close got me something. I'll let you know if they answer me. They did send an automatic e-mail saying they will answer me soon-for what that's worth.

  5. #5
    Join Date
    Jan 2010
    Location
    In a Pineapple Under the Sea
    Posts
    149
    An inverted P trap at the base of your verticle rise will not hurt anything if it gives you piece of mind to install one. You can make one with 2 service ells and 1 ell.

    Increasing your suction line size will actually slow your refrigerant velocity down and can prevent oil return if it is too big, so don't do that. Since these systems are small you would probably be okay just sticking with the line sizes recommended for your installation based on tonnage and overall lenght of the line set in the install manuals. See if Carrier responds back to see what the max verticle lift on the suction lines would be on the systems.

  6. #6
    Join Date
    Feb 2010
    Location
    Indianapolis, Indiana
    Posts
    34
    Carrier recommends no more that 20' vertical lift for these systems. I am going to have about 22'.

    Here is a question: Will it anything to have a trap in the suction line about halfway up (just to be on the safe side)? Also, how will an inverted P trap (I'm assuming you mean in the liquid line) help with oil return?

  7. #7
    Join Date
    Jan 2010
    Location
    In a Pineapple Under the Sea
    Posts
    149
    Quote Originally Posted by cholden324 View Post
    Carrier recommends no more that 20' vertical lift for these systems. I am going to have about 22'.

    Here is a question: Will it anything to have a trap in the suction line about halfway up (just to be on the safe side)? Also, how will an inverted P trap (I'm assuming you mean in the liquid line) help with oil return?
    I apologize inverted P traps are used for something else, You need a standard P trap on the suction line only.

    On high vertical lifts on larger applications a trap would be installed on the suction at the base of the lift then another trap every 20 feet. The lines would be sized properly to insure proper velocity for oil return and keep the pressure drop in the line to a minimum. The oil return would be done in stages this way. So if you do 2 traps now your adding 7 more ells to the suction line do they give you a max amount of ells with the lenght of your line line set in the install guide?

  8. #8
    Join Date
    Feb 2010
    Location
    butler pa
    Posts
    1,073
    id trap at the condenser and evaporator like we have been doing for years
    on walkin cooler/freezer installs..and i dont think an extra 2 feet on rise would be a major concern..
    and use long radius ells if you fab your own trap

  9. #9
    Join Date
    Jan 2010
    Location
    In a Pineapple Under the Sea
    Posts
    149
    Quote Originally Posted by pauls heating & View Post
    i dont think an extra 2 feet on rise would be a major concern..
    and use long radius ells if you fab your own trap
    I agree.

  10. #10
    Join Date
    Feb 2010
    Location
    Tulsa Ok
    Posts
    3
    ask your Carrier rep for a copy of their long lines application bulletin.

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