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

Heating all zones at once or make them take turns?

amSteve Member Posts: 1
Consider a residence with a manifold supporting 6 zones/pex loops that, taken together heat 1600 sf. It's an open floor plan without walls between entry/living/media/dining/kitchen. Beds and baths are on a different manifold.

Floating slab on grade -- 2" formular on the grade -- 1/2" pex stabled to the formular, covered by 4" inches of concrete.

Is it more efficient to run all zones wide open at once or can an argument be made that it's preferrable to devote the full boiler output to one zone at a time.



  • hot_rod
    hot_rod Member Posts: 22,251
    In a perfect system you would like to match the heat input to the heat loss without a lot of stop and starting of the components, boiler, pumps, valves, etc.

    The most efficient mode to run the boiler is off :)

    Next best is in it's "sweet spot" if it is a mod con, the lowest possible return with the burner modulating around the ever changing load, no, or very few stop/ starts.

    A properly sized and installed mod con on reset control, zoned within its modulation is about as good as it gets. If micro zoned below the lowest turndown, most mod cons are, in shoulder seasons especially, a buffer can help eliminate cycling.

    It always comes down to how good is good enough, control and $$ wise.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,039
    edited March 2021
    If bedrooms aren't involved, I like one zone, especially if it's an open floor plan.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • amSteve
    amSteve Member Posts: 1
    thx -- appreciated.