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Fin-tube under floor radiant

Bob Gruber
Bob Gruber Member Posts: 5
Anybody know where I can find engineering info (spacing & btu output)for fin-tube underfloor radiant?


  • Art Pittaway
    Art Pittaway Member Posts: 230
    Radiant with fin tube

    An almost identical post just fell off this site. Fin tube in the floor joist area or used under the front of a bathtub is documented back to at least the early 1950's. I have a great book called how to build a house for $3500.00 with reference to the tub. I do not believe I have ever seen engineering data for fin tube in this application. But, the bottom line is radiant systems have universally gone to tube stapled, clipped, or embedded in some type of floor, wall or ceiling. The companies provide sizing info, installation guides and warranties. Go to the "Manufacturers" and other sections of this site to learn more about radiant heating. Also the "Radiant Panal Association" has lots of info dedicated to radiant heating on there web site. Good hunting and safe 4th of July.
  • hot_rod
    hot_rod Member Posts: 21,793
    I'll bet

    there are lots of fin tube floor systems in service out there. Interestingly Larry Drake sent me pictures of this exact system in his dad's home. I suspect a 50's vintage.

    Basically convection transfer, probably need to run them a bit warmer than direct contact staple or transfer plate systems. Probably better transfer than plain suspended tube systems, however.

    I thought the older IBR design manuals touched on this, I may be hallucinating! Been a long hot day :)

    Seems the UltraFin system is trying to use this approch with pex as the conductor pipe.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    I stil install fin tube under floor. I just got done doing a master bath. The house was a remodel. If you are just trying to heat the room then put enough fin tube to supply the BTU's needed. I use 100 BTU's per foot. If under carpeting you can go every other bay or spaced even farther apart if you don't need much tube. If you are under tile or vinyl then you need some tube in every bay or you have to drill transfer holes between the bays to keep from having hot and cold spots on the floor.
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