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Expansion fittings for Copper baseboard runs.

hrhr Member Posts: 6,106
and it might not be a bad idea to use them a a 30 foot long run. The pipe has to move somewhere. Either end to end or it will bow up in the middle, and push on the holes at the end, causing noise.

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  • tony the techtony the tech Member Posts: 26
    Expansion fittings on 3/4\" copper tubing

    I had a question about expansion and contraction on Type m copper tubing. Here is my situation:
    The house is a cape style with baseboard heat. The feed and return lines exit one room through a wall take a 90 degree turn and then run for 30' in an unheated eve. Then take another 90 degree turn and come back into the room on the other side of the house. I want to move the 30' run out of the eve. I will basically be moving the tubing out of the eve into the rooms and just install enclosures to cover the tube since no additional heating is required. My question is, do I need some sort of expansion joint for a run this long? There is not one on the current run in the eve but it seams like a long run. I have never seen an expansion joint/conector for copper tube, do they mak them. Also where can I find general information about expansion /contraction info for different pipe/tube materials?
  • Mike T., Swampeast MOMike T., Swampeast MO Member Posts: 6,928

    From 70° to 180° copper tube expands about 1.3" per 100' of length. For 30' that amounts to about 3/8".

    Expansion loops (as opposed to expansion joints) are used for long runs of copper. Expansion loop is simply a up-over-down interruption. Can be made using tees or formed by bending. Doubtful that such is needed in your application. Copper tube should be firmly supported, but still free to move slightly. Expansion (slip) sleeves are made to prevent noise--particularly around fire blocking.
  • EmpireEmpire Member Posts: 2,343
    Expansion joints

    I agree with the above mentions and as long as you are not tight from end to end on that long run you should be ok. Example: We had a nursing home which to our dismay, had most of the copper 3/4" runs tightly incased in concrete in all of the rooms. Since there was absolutly no thought of expansion, we were force to use 3/4" expansion joints. It was kinda-fun to watch the apt. call for heat and see the bow in the middle grow larger and larger till it popped off the cover. Try it without the Exp Joint. You can always add it later. Easy to install. In addition, Slant/Fin corp. from Greenville, NY is the one I am lookin at right now. If you need it, call me if you like, I will fire it out to you @ cost plus what ever the shipping is.
    Good Luck
    Mike T/Empire Mechanical.(716)648-1763
  • bobbob Member Posts: 112
    Coefficients of linear expansion

    aluminum .0000133

    copper .0000094

    cast iron.0000059

    steel .0000063

    brass .0000107

    polybutylene .00027

    CPVC .000034

    PVC .00023

    PEX .00009

    To use these take the number of feet of pipe times the temperature difference times the coefficient the answer will be in FEET. Multiply the answer by 12 to convert to inches. If you enter the length in inches the answer will be in inches. The wall thickness of the pipe doesn't make any difference. bob
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