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Running Return Pipes Inside Fintube Baseboard?

Harry_6Harry_6 Member Posts: 105
I recently looked at an older home retrofitted with new(ish) fin tube baseboards, in which the installer brought both supply and return in at one end, supplied the fin tube, and ran the return back to the starting point with the return pipe resting on the fin tube, in the enclosure. Is this kosher? It seems like the pipe must be decreasing the heat emitting ability by partially obstructing the fins. Although I'm not sure running it along under the fin tube would be much better. obstruction is obstruction. He was obviously only wanting to have the vertical pipe runs furred in at one spot (they are on the second floor). I also have serious doubts about whether he took into account water temperature drop when he strung several together in series. Any thoughts?


  • Jamie HallJamie Hall Member Posts: 12,717
    Shouldn't be resting on the fins -- that may cause odd noises. But it won't reduce the heat output much.

    On the other hand, stringing several lengths together in series will. How much depends on the flow through them and thus the temperature drop. The output of a baseboard fin tube or otherwise -- is related to the average temperature, not the inlet temperature.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Intplm.Intplm. Member Posts: 1,135
    The return is supposed to be hung in the "enclosure" not resting on the fin tube. This is a common installation practice when no other path for the return pipe can be found. If it makes noise as @Jamie Hall points out. Than you should hang the pipe in the enclosure. Hangers are often provided and built into the baseboard "enclosure". Otherwise it shouldn't be of any concern.

    Also, the heat output should not be affected either.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,945

    1. Running the return line inside the enclosure is very common and considered good practice especially when the other end of the baseboard may have a piping obstruction. It's done all the time.
    2. The baseboard manufacturers commonly sell hangers for the return line for use inside the enclosure. It positions the return line on top of the fins
    3. Heat output with the return line installed over the fins does reduce the heat output (it's negligable)
  • Harry_6Harry_6 Member Posts: 105
    Thank you all for your insight and wisdom. I'll have to see if the pipe may have fallen from the hangers and needs relocation.
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