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Washbay Radiant Tube Depth and Installation Code for Cast on Grade Concrete Floor

I have a customer who put floor heat in his truck washbay, new construction. The contractor cannot tell me the depth of the tubing or the precise location so it is preventing me from installing the wash equipment as normal, with 1/2" concrete wedge anchors to a depth of about 3-1/2" is normal. I have not found any regulation, code, install instructions regarding this issue from anywhere. Even on this site the answers are vague and ambiguous to this question. Does anyone have a guide, code or instruction for 5/8" pex tubing depth and install for 6" concrete? I hit one tube in the washbay floor near the wall at a depth of less than 2" and am now reluctant to do anymore drilling. I was able to mount 90% of the equipment because we provided a lay out and anchoring plan in the washbay before construction which we crossed our fingers and went with. In the equipment room one pump ended up being moved to a new location due to the pipe routing and plumber preference. This is now causing the problem of the pump not being bolted to the floor. My goal is to provide the guideline, code or whatever, that should have been followed by the contractor which then relieves my responsibility if the anchor bolts penetrate a heating tube. I have read that zip tying the tubing to the rebar in a tight and know pattern is the correct installation method but cannot find it any where in AIA or manufacturers install guide. Help anyone?!


  • GGross
    GGross Member Posts: 696
    You would likely need to find out the manufacturer of the tubing first. In my experience the tubing manufacturer will specify a recommended depth for given applications. The reality however, is that it is very difficult to install tubing in a slab at an exact depth, and generally speaking it is not possible for the tubing to all be at the same depth in a 6" slab. Manufacturers would tend to recommend the tubing be suspended higher in a deeper slab, to allow better heat transfer to the floor surface. If I had to take a wild guess I would have to guess that the installer is within all manufacturers guidelines, but I am interested to hear what you find out. There may also be separate codes that apply to your state, or commercial codes for your application. If an engineer is involved, include them in this as well

    I have designed several similar jobs, and we are generally instructed by the engineer as to where equipment will be installed in the building, so that we can avoid those locations with tubing. In one case we had an issue like yours, where the building owner left the equipment off the print, because he did not want the county to inspect his building as a "mechanics shop" and instead build it as a heated storage building. i believe they were able, with the help of infrared camera, to determine where the tubing was in order to avoid it in the equipment anchoring process.
  • GroundUp
    GroundUp Member Posts: 1,652
    There is no code specifying a tubing layout or depth- every job is different. Either you get yourself some thermal imaging equipment and find the lines to avoid, you use shorter anchors, or you make a deal with the owner that you're not responsible for hitting any of the tubing. If you already hit one at 2" deep, assume it's all 2" deep. It could be anywhere from 6" to 24" apart, depending on the knowledge level of the installer. I find it very hard to believe that the installer can not tell you the spacing or depth- this sounds pretty sketchy.
  • johnsonwash
    johnsonwash Member Posts: 2
    Thanks for your comments. The General is not being very cooperative, this is owner furnished and installed instead of through the GC. Owner saved the markup cost of my equipment but then has an uncooperative contractor. It's too bad some regs are way strict and others of importance are non-existent. Thermal ratings and concrete strengths are very thorough sciences and we have combined them for decades now. Alas, there is also no reg for how to clean out a milk hauling tanker truck before it gets filled again. The only criteria there is industry provided and the hazards of in floor radiant heating install criteria are likely not deadly. :smiley: We will take the thermal imaging route and put this to rest, unless the tubing is in the way, then epoxy maybe.
  • hot_rod
    hot_rod Member Posts: 19,896
    Its pretty amazing what you can do with epoxy anchor methods these days.

    The infrared camera would locate the tube accurately, but not the depth.
    2" below the surface is an ideal location for tube for both heat flux and for adequate aggregate coverage over the tube.

    Tube rarely stays exactly where it is placed, especially when the mud is pumped over it.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream