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Thread: Lineset Size

  1. #1
    Hello,
    I am in the process of having my existing HVAC system replaced. Everything except the existing duct will be changed out. My existing condensor had a burn out therefore I requested that the original lineset be changed. The condensor being installed is a 4 ton 14 Seer Goodman CLT48 and the coil is a Goodman CAPF061C2A and the furnace is a two stage Goodman GMV90905CXA.

    My question is regarding the lineset size. The installer is planning on replacing the lineset with another 7/8" suction line. I was reading in the installation manual that Goodman specs a 1 1/8" suction line for installations with lineset lengths greater than 25'. My lineset length will be just under 35'. From the coil it will run about 2' up and out of the utility closet and about 22' through the attic and then drop from the eave about 8' and then about 2' over to the condensor. The installer indicated that the 1 1/8" is overkill for this installation and that 7/8" should be used. What are your professional thoughts on this? Also, is 3/8" insulation on the suction line adequate? I am concerned because this line will be running 22' through a hot Texas attic.

  2. #2
    Join Date
    Jun 2003
    Location
    Florida
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    9,548
    If you don't install what is spec'ed, you won't get the spec'd seer,14 in this case. Use the proper size.
    If everything was always done "by the book"....the book would never change.

  3. #3
    Senior Tech Guest
    The installation manual from the manufactuer is the "rule book", break the rules in the book and while technically under warranty the manufactuer could, should and will void the warranty in some cases....

  4. #4
    Join Date
    Apr 2004
    Posts
    7,680
    His opinion is dictated by convieninece. He would hack in soft copper for the 7/8 but would actually have to do some real piping if he installed 1-1/8 because its generally hard pipe. If it says 1 1/8, I would insist on it.

  5. #5
    Thanks guys I appreciate the responses. I should have mentioned this in the beginning that a TXV will be installed. Does this change the situation? Also, what do you guys think about the 3/8" suction line insulation? Is this sufficient for this line since it will be ran in the attic or should I request thicker insulation on this line?

  6. #6
    Well yesterday afternoon my furnace and coil were installed and the condensor was set. I talked the installer into not running the 7/8" lineset and he is now ordering a 1 1/8" lineset. He did tell me that he could only get this line preinsulated with 3/8" insulation. Is this insulation sufficient since this line will now be ran through the attic?

    One item that really upset me with the furnace install was that my old furnace used double wall 5" metal pipe for its exhaust. My new furnace has a 3" PVC exhaust. The installer pulled the old metal pipe and ran the new PVC pipe through the roof using the same roof flashing which is way too big for the new PVC pipe. He told me it was up to me to get a roofer to replace this boot/flashing. Is this typical or would you guys normally replace this yourself during an install?


  7. #7
    Join Date
    Dec 2005
    Posts
    783
    Was this supposed to be a complete install? Did he tell you up front about calling the roofer before he did the install?

  8. #8
    My belief was that this was to be a turn key job. Nothing up front was mentioned about involving anyone else to perform any roof work. He just mentioned that for liability reasons he could not install the roof jack? Is this normal?

  9. #9
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Did you hire el-cheapo? First off he can buy insulation for any size lineset, instead of "pre-insulated". Second, it's his responsibility to replace the roof flashing, now whether he calls in a roofer or not is his call. If it leaks, it's on him,as he pulled the old flashing.Be careful recommending this outfit to anyone....I wouldn't,just from what you've posted.
    If everything was always done "by the book"....the book would never change.

  10. #10
    Join Date
    Apr 2004
    Posts
    7,680
    From start to finish it sounds like a low budget job. If it makes you feel any better, if someone had quoted you to do it correctly... you would have probably paid more.

  11. #11
    Join Date
    Sep 2004
    Location
    Memphis
    Posts
    2,502
    There is no way I would go for that pvc pipe being run through the old flashing. That has to look horrible. Did he run a 2nd pipe for the combustion air? I would be recommending a concentric vent kit. It can penetrate the roof in the same spot you have the hole. He will need to replace the flashing with a rubber flashing like the plumbers use, but this isnt hard at all. I have never dreamed of telling a customer he had to get a roofer to do this. Its just not that hard.
    Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.

  12. #12
    Join Date
    Apr 2005
    Location
    new jersey
    Posts
    752
    preinsulated rolled 1x1/8 lineset is ok.keeping it clean and straight can be a litle tough.When changeing out a 80% to a 90%,the chimny being changed to pvc should have been discussed from the very beginning in a contract/proposal.at least i would have mentioned it.

  13. #13

    Question

    the 3/8" insulation on the Suction line is a bit weak and should be at least 1/2". The liquid line should be insulated as well if the lines are running through an attic like you had mentioned, this will keep your subcooling up and provide maximum efficiency. If you don't insulate the lines like I suggest then you are probably going to have problems in the future.

    Cheers

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