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Are expansion couplings required for new install of baseboard heaters?

newtonkid88 Member Posts: 102

I'd rather install them during the new install rather than wait to see if I have a noise issue later on.

The long lengths will be 5' + 5' to make a 10' element. And also either a 14' or 15' length,

Any thoughts?


  • Ironman
    Ironman Member Posts: 7,379
    A 100’ length of 3/4” copper tubing expands about 1” in length when its temperature is raised 100*.

    There always needs to be some allowance made for expansion, but on shorter runs drilling holes that are at least 1/2” larger than the tubing will suffice. Just make sure the tubing is centered in the holes an not locked tight against the sides of them.

    Expansion couplings should only be necessary on extremely long runs.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • mattmia2
    mattmia2 Member Posts: 9,753
    If you are concerned about noise I would look very carefully at how the carriers are constructed on the various models. They all are essentially a piece of plastic that the element can slide on but there are numerous versions.

    I would make sure the piping or tubing in the basement can move, that it has some sort of open area to expand and that the risers can move horizontally and can tilt a bit as the element expands and contracts. Remember the piping feeding it will expand and contract too, make sure it isn't restrained and make sure the ends aren't pinned up against anything.
  • mattmia2
    mattmia2 Member Posts: 9,753
    The other ting that will help a lot with expansion noise is even if you are running a conventional boiler, running an outdoor reset mixing valve that can match the water temp to the load so it stays at about the seam temp most of the time.
  • hot_rod
    hot_rod Member Posts: 22,268
    What you can see happen if there is no room for expansion at the ends is the fin tube will actually arc up off the supports. The plastic sliders stay stuck to the fins to eliminate movement noise.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • HomerJSmith
    HomerJSmith Member Posts: 2,468
    edited July 2022
    I bought a bunch of these that were Navy surplus for my sys that I installed in the '80's.
    One failed, what a mess. Several others are still in operation with no problems. Same accordion design. One of these days, I will take them out, one of these days. It is always the plumbers house that has the leaky pipes. Truthfully, unless my wife constantly complains to me, it probably won't get done.

    My thinking is I don't trust them. Slantfin had some sleeve types that had an O-ring, as I recall.

    What ever you do. DO not put them in a wall or ceiling cavity covered with drywall. They must be accessible.