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Radiant heat and condensation worries

BenWoj Member Posts: 33
I'm in the process of replacing my baseboard heating with underfloor heating. All but one room has been converted and as I'm thinking about water temps, I vegan to have questions.

If I keep my boiler at its current temperature to heat the one baseboard heated room, I'll need a temp mixer to cool down the loops with underfloor heating, but how much before I have to worry about condensation? Do I monitor return temp to make sure I'm always above 140 degr?

Thanks ahead of time for the replies


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    without knowing any of the details.....

    Yes, you should have mixing and boiler protection.  Hopefully you or someone designed the whole system for radiant, and you'll know the temps you'll need.  You'll be below 140 for sure and will need pri/sec piping or a 4 way mixing valve, for starters, with outdoor reset. I wouldn't raise the temp just for the one room of baseboard, without doing the math.  If your lucky the baseboard is oversized, (or you could add more) and it wont matter.  Splitting it into its own zone may cause short cycling.
  • BenWoj
    BenWoj Member Posts: 33

    I'm still doing my fair share of research before I get it up and running (hopefully sooner than later)

    Correct me if I'm wrong, but a 4 way would work better then a three way because it would return a higher temp to the boiler?

    I looked at doing an outdoor reset, but from what I've read since I don't have a condensing boiler my temp will have to stay above 140 deg which doesn't give me much of a benefit. Is this something I should read into a little more?

    I'm not sure if I'm doing my heat loss cal correctly. Would anyone be able to check my math?

    Room is 27 x 15

    Front exterior wall is 27 x 6. R23 4 windows, each one is 2'10" x 1'3"

    Side exterior wall is 15 x 8. R23. French doors 72" x 80"

    Back exterior wall is 27 x 6 R23. No windows

    Side interior wall is15x 8. R23. A door 36 x 80

    Ceiling is vaulted so there's two 27'x 9'. R33.5

    I'm Michigan so my T I've been using is 72 and -10
  • Zman
    Zman Member Posts: 7,550

    Outdoor reset will improve the comfort of the radiant side.

    Tekmar makes some really nice controllers that provide reset and boiler protection. 4 way mixers or injection pumps will do the same thing.

    Tekmar make the controls for the Taco X blocks. A nice clean solution.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • BenWoj
    BenWoj Member Posts: 33
    Taco x block

    Thanks for bringing that up Carl, that's something I'd be very interested in. Looks like I can connect more than one zone to it as well. Need to calculate gpm, head, as well as other heat loss in additional rooms.

    When doing my load calc I came up with about 4044 btu/h.

    Does this seem right?
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