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  1. #1
    Join Date
    Aug 2012
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    Liquid line 5/16 inch vs 3/8 inch


    Again, thanks for all of your good advice, it has been helpful.

    I have one additional question after having a new install.

    I was told by the contractor before the install that the line set wouldn't have to be changed. He said he would flush out the lines when changing from R-22 to the 410a.

    Even though the run is 25 feet or under and the lines would have been easy to change out, I consented since he said the sizes would be the same.

    After the install, I noticed that where they brazed or connected the XL 16i to the liquid line was bigger on the air conditioner side.

    I measured and found out that they brazed the 3/8 inch line to my existing 5/16 inch line.

    My units are:

    Trane XL 16i 4TTX6036
    Trane Furnace TUH2B080A9V3 2 stage 95% efficient 80,000 BTU
    Coil- 4TXCB004

    Looking at the installation documents (from Trane online), I find that the XL 16i calls for a 3/8 inch copper liquid line and the coil also calls for 3/8 inch.

    I brought this up with the installer and he said that it wouldn't matter because it was only 25 feet in length.

    I'm more of a precision guy and would use what is called for regardless of wiggle room.

    I calculated the volume of liquid in 3/8 in 25 ft tube vs 5/16 in 25 foot tube and came up with 32.97 and 22.98 cubic inches respectively within the distance of the line. These calculations are based upon the formula V= Pi x r2 x length.

    I don't really understand whether the flow rate or volume make a difference in the liquid line, but if they do then there is around 30% less liquid in the smaller 5/16 inch line.

    This may be picky and I really don't know, but I'm concerned.

    I still wonder though if this could void my warranty, affect the efficiency of my system or cause additional wear and tear and lesson the life of my $ new system!

    I'm wondering if I should demand the correct liquid line size or perhaps take up the matter with Home Depot (their contractor) or Trane?

    What do you guys think?


    Last edited by beenthere; 08-21-2012 at 05:31 AM. Reason: price

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