Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Radiant heating safe?

Bosco Member Posts: 26
Due to extremely cold weather ,Is it safe to turn on boiler 24/7?


  • Jamie Hall
    Jamie Hall Member Posts: 16,602
    Say what? If the boiler is properly installed, and the safeties on it are working as designed, why not?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,188
    If your system was designed perfectly, in an ideal world you would have true thermal equalibrium, and your boiler would be running 24-7.
  • Zman
    Zman Member Posts: 6,790
    I would suggest combining your 2 posts and providing some pictures. It sounds like you have a design/installation error in your system that should be investigated.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    If my boiler would run 24/7 for all outside temperatures below 70F (my warm water shutdown temperature), I would think I have got the outdoor reset curves just right.

    My boiler will run each of two zones with their own reset curves, which is just what I need because my radiant slab at grade zone has completely different needs than the fin-tube baseboard zone.

    My downstairs thermostat called for 13 hours 22 minutes of heat yesterday, when it was kind-of cold out. A day starts at 12AM each day and runs until 12PM of the same day; i.e., 24 hours. The missing hours were during the daytime.

    My upstairs thermostat does not record its on-time. It comes on and off more often because it is baseboard and not radiant slab.

    It took me several years to get the ODR curves set well. I did not wish to pay my heating installation company big-bux/hour to sit around to diddle the curves, so I did it myself. I first calculated the ODR curves from my heat loss data, and that helped a little bit, but I made too many assumptions about thermal conductivity of the exterior walls, and the leakage due to strong outdoor winds. The big problem in setting the curves is that I cannot set the outdoor temperatures and hold them for a couple of days at a time; I must wait for nature to change them. With radiant slab, things do not change quickly.
  • Gordy
    Gordy Member Posts: 9,514
    Your heating system should be on. The thermostat will tell the boiler when to turn on, and off. No need to manually turn on heating.

    But then some assumptions are made in my statement.