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Uponor HePex installation

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JS41190
JS41190 Posts: 20
in Radiant Heating

We are installing several loops of 1/2” HePex from the underside of the subfloor for an existing space. I’m wondering if you need to use the Uponor clips, or could it be installed using plastic two hole straps? The homeowner did not want to use the transfer plates, so we’re trying our best.

Comments

  • Ironman
    Ironman Posts: 7,959

    That’s a huge mistake!

    You’re only gonna get about 7 btus per square foot without plates.

    You’ll get about 20 btus per square foot with plates @ 120* SWT.

    You’re the pro. Don’t let the homeowner design the system! He’s wanting to do it cheap, but the laws of physics don’t yield to the laws of economics.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    JS41190
  • JS41190
    JS41190 Posts: 20
    https://forum.heatinghelp.com/discussion/comment/1906242#Comment_1906242

    I agree! We discussed the issue with no plates and the homeowner didn’t want to hear it. Luckily we told them it won’t work as good as it could with the plates and they still wanted us to proceed. Unfortunately we can’t force someone to do something. Would it be better though to use the Uponor clips, or just plastic flat straps?

  • hot_rod
    hot_rod Posts: 28,463

    is this intended to heat the rooms, or floor warming?

    Uponor calls it joist bay heating, they have a track for installing the Pex.

    These tend to need high supply temperatures, 140 plus.

    Do you have heat load numbers for the various rooms?

    IMG_1662.jpeg IMG_1663.jpeg

    The key to any radiant installation method is getting the floor surface temperature up. You get about 2 btu/ square foot per degree difference.

    So a 82 degree floor surface in a 70 degree room = 12x= 24 btu/ ft

    Getting the floor surface that warm by heating the air in the space is the question.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mattmia2
    mattmia2 Posts: 18,160

    will it or something else cover the heat loss?

  • hot_rod
    hot_rod Posts: 28,463

    Watts Radiant has been claiming up to 20 btu/ square foot per ft with suspended pex. It may take 180 supply to get that.

    IMG_1665.jpeg
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JS41190
    JS41190 Posts: 20
    https://forum.heatinghelp.com/discussion/comment/1906249#Comment_1906249

    This is intended to heat the space, along with (2) toe-kick heaters. I saw the tracks, but the homeowner was dead set against using them because of cost. We explained it may not work as well, but I can’t argue with them.

  • JS41190
    JS41190 Posts: 20
    https://forum.heatinghelp.com/discussion/comment/1906253#Comment_1906253

    Thank you for this. So essentially securing the tubing directly to the underside of the subfloor below would be the best bet if not using the tracks?

  • JS41190
    JS41190 Posts: 20
    https://forum.heatinghelp.com/discussion/comment/1906257#Comment_1906257

    Nope, I just found your post online and it’s saying the pex will cause noise. Guess I’ll be using the clips instead.

    hot_rod
  • JS41190
    JS41190 Posts: 20
    https://forum.heatinghelp.com/discussion/comment/1906250#Comment_1906250

    There are also two large toe-kick heaters in the space.

  • hot_rod
    hot_rod Posts: 28,463
    https://forum.heatinghelp.com/discussion/comment/1906259#Comment_1906259

    yeah Pex squirms a lot especially when you run it up to high temperatures needed with joist bay application. Use an attachment designed for quiet movement. Avoid the pex touching or crossing itself. The outer layer can create a squeaking noise when it rubs. The loop ends need to be unfastened to allow the pex to grow in length, quietly.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    JS41190

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