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  1. #1

    Liquid line 5/16 inch vs 3/8 inch

    Hello,

    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?

    Best,

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

  2. #2
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    On a 3 ton system, with the length of line you have, the difference in the pressure drop between a 5/16 and 3/8" liquid line is fairly small, and is far far below the 50psi maximum allowable, so there is no affect on efficiency.

    The lower total volume of refrigerant in the system actually potentially makes for a slightly more reliable system, with lower cyclical efficiency losses.
    If more government is the answer, then it's a really stupid question.

  3. #3
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    Why did you go to Home Depot for HVAC? They just sub work to a contractor and make money by essentially being a broker. I always changed out line set on a 22 to 410 replacement unless it is inaccessible or there is no other feasible route. In most cases an oversized liquid line will not cause any problems but the fact of the matter is An oversized liquid line increases refrigerant charge. Increase in refrigerant charge will increase the possibility of liquid migration Off cycle migration causes flooded starts and flooded starts over time kill compressors.

  4. #4
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    I agree that on this system you probably won't have migration problems

  5. #5
    Thanks for the response.

    I have drafted a contract for the contractor and Trane to sign off on regarding the size of the liquid line not having any ill effect, voiding or affecting my warranty.

    Regarding the Home Depot guy:

    I live in a town of 70,000 people and there are a limited number of contractors. This guy was also recommended by several friends.

    I'm guessing that part of the problems I'm having is due to the oppressive Midwest heat and that they are all so busy that they arn't taking time to do a proper job. They also may be hiring more unskilled workers to fill in the gap.

    But yes, I think I got ripped off by the Home Depot contractor.... $$$$ for a XL 16i 3ton, XV95 80,000 btu, humidifier and thermostat (after $1050.00 in rebate incentives from the utility companies)
    Last edited by jpsmith1cm; 08-20-2012 at 04:55 PM. Reason: Pricing

  6. #6
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    Quote Originally Posted by Hammerwolf47 View Post
    Thanks for the response.

    I have drafted a contract for the contractor and Trane to sign off on regarding the size of the liquid line not having any ill effect, voiding or affecting my warranty.

    Regarding the Home Depot guy:

    I live in a town of 70,000 people and there are a limited number of contractors. This guy was also recommended by several friends.

    I'm guessing that part of the problems I'm having is due to the oppressive Midwest heat and that they are all so busy that they arn't taking time to do a proper job. They also may be hiring more unskilled workers to fill in the gap.

    But yes, I think I got ripped off by the Home Depot contractor.... $$$$ for a XL 16i 3ton, XV95 80,000 btu, humidifier and thermostat (after $1050.00 in rebate incentives from the utility companies)

    No he didn't. You should have gotten other estimates. He gave you a quote, and you had the opportunity to reject it.
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  7. #7
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    Quote Originally Posted by beenthere View Post
    No he didn't. You should have gotten other estimates. He gave you a quote, and you had the opportunity to reject it.
    X2

  8. #8
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    Quote Originally Posted by Hammerwolf47 View Post
    Thanks for the response.

    I have drafted a contract for the contractor and Trane to sign off on regarding the size of the liquid line not having any ill effect, voiding or affecting my warranty.
    I entered the numbers for a little bit longer line set than you have into Trane's piping software, with a vertical separation and number of elbows that is almost certainly more than you have, and came up with a recommended LL size of 5/16, and SL size of 5/8.

    A 3/8" LL is actually a less desirable size due to the extra total refrigerant charge.
    A 3/4 or 7/8" SL can also be used.

    Quit stressing about it.
    If more government is the answer, then it's a really stupid question.

  9. #9
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    I have drafted a contract for the contractor and Trane to sign off on regarding the size of the liquid line not having any ill effect, voiding or affecting my warranty.
    Trane won't be signing it.
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    How many times must one fix something before it is fixed?

  10. #10
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    Quote Originally Posted by beenthere View Post
    Trane won't be signing it.
    Neither will the contractor if he has any sense

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