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Radiant Tubing Installation

Poacher Member Posts: 3
I conducted an energy audit of a new modular set last October.   The owners complain of very high fuel consumption.   Some building shell defects were found but the biggest concern is how the radiant tubing was installed for the first floor.  It is a "dry" installation and the tubing is side stapled to the 2x10 floor joist and is between 2-6" below the subfloor.  There are no heat diffusers and the floor has kraft faced R19 batts.  Some of the tubing was actully sticking below the batt insulation and a good percentage of the tubing was covered with the batt insulaltion.  The manufacture stapled the tubing 2" below the subfloor then it loops downward between the staples.  Picture attached. The tubing is also attached to the exterior rim band. The basement is not conditioned and the house is in NH (8000+ HDD).  I believe it is safe to say that this is very inefficient in that a good percentage of the heat energy is going to the cold basement.  I am looking for a published standard to refer to on the installation of the radiant floor heating and / or your comments on how inefficent this installation method is. 


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Warm Earth Worms....

    Unfortunately, there is not a recognized industry standard, only manufacturers installation instructions, and none of the reputable manufacturers I know of would ever approve of that methodology for tubing installation. Common sense also says it is not wise to hang a hot tube on a cold exterior rim joist.

    Best recommendation would be to place extruded aluminum heat transfer plates with the tubing tightly snapped into the receiver to get it into the right shape.

    The Radiant Professionals Alliance has merged with the IAPMO organization, and it is their intent to produce an actual hydronic "code" standard that will eliminate (hopefully) crappy installation methods like has been deployed on this project. I look forward to assisting in that effort.

    Go here to see an excellent article by a respected industry educator/engineering type regarding staple up tubing installation.


    While there, check out their extruded aluminum heat transfer plate. I tested them at the college I used to work at, and they are VERY effective.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • kcopp
    kcopp Member Posts: 4,386
    edited April 2012
    Im in New Hampshire....

    what a shame... prob no heatloss done and obviously a poor install. What town is this in? Best way to fix it is to pull all the insulation down and start again. Do the math 1st!
  • SWEI
    SWEI Member Posts: 7,356
    Hydronic Wall of Shame

    candidate for sure.  They must have been terribly concerned about the flooring guys nailing the tubing, so they decided to place it safely out of harm's way.

    I look forward to seeing what comes of the IAPMO efforts.  Knowing that ME is involved lowers my blood pressure a bit (whenever I hear the phrase "new code" I tend to cringe a bit.)

    We'll be tearing the Venetian plaster ceilings out of a very nice house this summer in order to post-install plates.  The original installers used 3/8" plywood standoffs to keep the tubing from touching the subfloor, then installed foil-faced polyiso 2" below the tubing.  Atmospheric boiler cranks away all day at 140-150F (no mixing valve) and short cycles on the slab below while freezing the second floor.
  • Gordy
    Gordy Member Posts: 9,546
    New method

     Of radiant heating. Indirect radiant heating IRH. You heat the floor joist, and it heats the floor. Some draw backs. Floor joist are not a very good conductor of heat, and stripping with layout at 16" oc..............Just kidding UGHH. I can imagine the modular sales pitch. Oh goodie RFH is an option. I wonder what that option cost.

This discussion has been closed.