I have in-floor water radiant heating. There are five zones of varying sizes. In some larger zones there are multiple circulation loops split from the supply and then recombined for the return.

I understand why there are multiple circulation loops. In my setup when there are multiple loops in a single heating zone there are also multiple zone valves (one for each loop within the zone.)

Multiple zone valves in the same heating zone (as I have now) all activate at same time when there is call for heat. This seems to create more wiring and valve complexity and more to go wrong

Why isn't there just one zone valve per zone on the supply line, which would then split after the valve?

  • Maybe to isolate a section if part of it fails.
    – JACK
    Oct 17, 2021 at 17:58
  • I feel like failure isolation is best achieved with a simple ball valve rather than an electronic zone valve
    – Matthew
    Oct 17, 2021 at 18:27
  • You say that zones within zones "all activate at the same time". Is that an observation? Or, are they all wired in parallel so they definitively only can be open or closed simultaneously? Can you trace the control wiring from each sub-valve back to the device, or chain of devices, that control it?
    – jay613
    Oct 17, 2021 at 23:57
  • They are wired such that they can only actuate together.
    – Matthew
    Oct 18, 2021 at 0:25

1 Answer 1


Difficult to know for sure without asking the designer. For instance, there might be limiting sensors to keep the floor from getting too hot, that might be per "loop zone" rather than "per room zone" so they might all start together, & then some of them might stop before others.

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