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Potential issues with sleepers above floor radiant heat type of install.

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DrVit
DrVit Member Posts: 17
in Radiant Heating
I started to do install in my bathroom with sleepers method using Advantec 3/4" boards cut for sleepers.
(https://www.radiantec.com/installation-manuals/installing-tubing-within-a-subfloor/)

One concern I have - considering pipe will expend/contract between sleepers, especially on turns - would that be an issue with pipe rubbing floor under it, sides of sleepers, etc ? Which eventually can cause pipe failure in "rubbing spots"? I also not particularly fan of relatively sharp edges of the plates.

One of the potential solutions to minimize possibilities of damage due to friction - I was thinking about placing maybe caulk on plates edges and around the pipe on turns? Any suggestions from those who did this type of install?

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  • Jamie Hall
    Jamie Hall Member Posts: 23,280
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    Nor caulk. I agree with your concern, though, about the ends of the aluminium plates. What I would do is snip about a half inch into the end of each plate, right at the groove on both sides, and then fold the resulting little tongue over on top of the plate. This will give you a nice folded edge for the tubing to rub on, which shouldn't be a problem. Make sure the cut edges on the sides of the groove are just beyond the edges so the tubing can't reach them.

    Try, by the way, to use true 3/4 inch ply. Some of the big box stores sell plywood with millimeter thickness -- and may try to pass 18 mm ply as 3/4 inch. It's not. If all you can get is millimeter, go to 20 millimeter.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    DrVit
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2019
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    Caulk is a wasted effort. It’s certainly not as durable as pex pipe. Stop the plate short of the radius, so you have a few inches of straight pipe before turning the radius. Pex with plates, and sleepers are done all the time.

    While expansion over the total length of a loop seems like a lot. It’s not that much movement in each radius. If your design water temps are low, and constant circulation is used expansion / contraction is minimized, along with noise.

    What kind of plates? Extruded omega channel? There is a difference.
    DrVit
  • DrVit
    DrVit Member Posts: 17
    edited January 2019
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    @Jamie Hall Any difference between OSB 3/4 and Ply 3/4? Thanks for advice on cut/fold. Will try that.

    @Gordy . Using Omega channels. Bought them from Radiant Store, but concerned with some imperfections of stamping.

    https://www.ebay.com/itm/100-2ft-Aluminum-Radiant-Heat-Transfer-Plates-for-1-2-PEX-Tubing-OMEGA-SHAPED/390682180453?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
  • Jamie Hall
    Jamie Hall Member Posts: 23,280
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    No -- for what you are doing either one is fine. Just, as I say, check the real thickness.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    DrVit
  • hot_rod
    hot_rod Member Posts: 22,131
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    thin transfer plates have a habit of "oil canning". A ticking noise when they heat and cool. One manufacturer use to suggest silicone in all the grooves, a messy job for sure.

    Another pex manufacturer suggested leaving one side un-fastened to allow plate movement. Both kinda dumb solutions :)

    PAP helps limit tube movement also.

    Ideally the thick extruded plates that grip the tube tightly, Radiant Engineering ThermoFin, for examplefcrs
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    DrVit
  • DrVit
    DrVit Member Posts: 17
    edited January 2019
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    @hot rod_7 I doubt that leaving one side un-fastened will help with noise reduction, as to me - it might do just opposite :). But I will try to use thermal silicone, same as I think they use in Uponor Track system. I hope it might help, as it should create somewhat "cushion", but its also thermal conductive.
    Something like this:
    https://www.ebay.com/itm/12oz-Tube-Aluminum-Thermal-Conductive-Sealant-Radiant-Heat-Transfer-Plates-PEX/252928086475?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    As for Thermofin - if you mean TF C - I've used similar Uponor plates, but for under the floor install. I figured I'll try Omega type for above floor.
  • plumbbob
    plumbbob Member Posts: 19
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    i set it up the same way only difference we laid out aluminum sheets down onto the floor and screwed sleepers on top,it covers more area and cheaper also
  • hot_rod
    hot_rod Member Posts: 22,131
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    The concept of letting one side of the plate “float” was promoted by a manufacturer that sold the plates as a “work around”

    Never tried it myself, I understand the concept, allowing some movement

    Regardless, I rather not tempt fate

    I see a few different plates. The thin flashing thickness style,

    Extruded plates offered in two different thickness and weights. The cost Is directly related to the weight of the aluminum.

    A good first step it to assure a tight fit to limit expansion noise in the tube to plate connection. Next the best contact to the floor. I consider the silicon adhesive as another work around.

    There are good applications for both “C” and “U” profiles. The U profile I have used were the heavy gauge, not sure they are offered in lite version. At least from ThermoFin brand.
    The lite C version may have been designed for OEM resellers😜. It’s still possible to have a tight fit in lite plates, depends on where you put the aluminum in the extrusion, and closely controlling the temper of the aluminum.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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