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Repair pinhole leak in radiant tubing in track on the floor

Last summer I installed Warm Board radiant. It is 1 1/8" toungue and groove structual plywood with routed tracks and aluminum skin covering the entire surface. I installed Wirsbo 1/2" MultiCor pex tubing.

We installed padding and carpeting in August. Last week a small damp spot appeared and we found that one end of the padding staple had penetrated the tubing.

The only coupling Wirsbo makes is an enormous brass piece with two huge brass nuts. It would cause extensive chiseling of the Warm Board to get it to lie flush in the track.

Does anyone know of a glue or adhesive that would work? Currently I have a 1/2" square 1/4" thick of rubber gasket cut from the gasket of a toilet flapper valve which is help in place by a small nylon tie. It's holding but I'm just not sure of its long term reliability.

I also thought a small stainless hose clamp and some other kind of rubber might work but I am somewhat concerned the clamp could crush the tubing.



  • Michael Welch
    Michael Welch Member Posts: 43
    Brass coupling

    The way we have always done it is to cut the tubing back router out with a roto zip a gap big enough to sink the coupling down below floor level. Has worked every time that someone has hit a line on us. You can do it the right way or do it twice later down the road.
  • hr
    hr Member Posts: 6,106
    I'd use a simple

    pex coupling with crimp rings. A little chisel work would allow it to sit in flush.

    Or find some of these Odiker crimp rings as the tool only needs to grip those ears to crimp. With that style the repair could be pushed down into the groove then crimped.

    With a little room on either side of the nail spot you cut right through the nail hole, lift both ends of the tube, install the rings, lower it down and crimp.

    I've repaired a few WB leaks with that method.

    You would need a big excavation to get wrenches around those nuts to tighten a compression style coupling.

    I've also repaired Warmboard leaks from below, via crawlspace access. After locating the nail I cut a window out of the Warmboard and pulled the tube down to splice.

    hot rod

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  • Darrell
    Darrell Member Posts: 303

    What about the Q/E fittings by Wirsbo? They are technically for use in the domestic water lines...but they work great in the heat lines as well. Easy to use, thermoelastic, thermo-responsive, low profile, and permanent. Use the brass fitting. I've never had a failure with thousands of joints of one kind or another in the field...we use them for the manifolds. Any other kind of mechanical joint can potentially work loose.

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  • Ted_9
    Ted_9 Member Posts: 1,718
    wirsbo repair 5/16 pex

    We repaired this one on Friday. It was too close to the back wall under the cabinet to get one coupling to sit flat. so we went with the loop.

    BTW, I thought you could only use multicore fittings with Wirsbo pex-al-pex? I have a whole back of couplings because the supply house didn't stock them and made me get the bag from Urel. One more reason I don't do business with that transfer house. If you need the coupling, I'll send it your way.


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  • hr
    hr Member Posts: 6,106
    Sorry I missed the MultiCor

    tube. But they do offer a crimp style coupling for that also. It has an o-ring and a deeper stainless crimp collar. And you need the special crimp tool, and tube expander/ reamer.

    A bit more complicated... maybe back to the compression coupler :)

    hot rod

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  • heatboy
    heatboy Member Posts: 1,468
    That's all they make........

    ........for MultiCor couplings. I have had more than my share of punctures caused by other trades. Depending on the tube size, I'll take a 2" to 2 1/2" hole saw and cut a hole down through the transfer plate until the pilot bit protrudes through sub-floor. Make up whatever coupling you need and it will lay right down in the hole. The pilot hole through the sub-floor will allow any possible future leak to go straight down instead of following the plate to who knows where causing even more damage.

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  • Bob Luz
    Bob Luz Member Posts: 1
    Fix for MultiCore

    Hot Rod, Crimp Fitting on Pex-AL-Pex? Are you sure?
    Suggestion: Use staight Pex-A and use ProPex Plastic coupling below floor. No more MultiCore (Pex-Al-Pex) Can't fix it.
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