Modulation with Multi Zone

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jimb
jimb ✭
in General Questions & Topics
I am looking to purchase a Valliant Ecotec 938 or Veissman 111-w. This will drive 1 zone of radiators and 2 UFH zones (via 2 port valve).

I am thinking to go for the Tado 3 Wireless EU version to modulate the radiator zone via eBus/OpenTherm. I assume I would need 2 wired thermostats for the 2 UFH zones.

Would the wired tado controllers for the UFH support modulation? If not, and it’s simple on/off - can either of these boilers handle being controlled by bus/modulation AND simple relay from the UFH at the same time?

Is my question even sensible, or am I barking totally up the wrong tree here?

Answers

  • johnnyp78
    johnnyp78 ✭✭✭
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    If you search the forum people have asked about this before. I think in theory it’s possible but with a modulating connection your ufh will heat up very slowly.
  • GrilledCheese2
    GrilledCheese2 ✭✭✭
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    Digital bus control provides load compensation, which is suited to a single zone. Multiple zones will have different heating characteristics, so modulating the flow temperature for different loads provides little if any benefit. The UFH zones will certainly have a much slower response compared to radiators because they have to heat the floor before the air. Also, your UFH will be designed to work at a fixed temperature and there's likely to be a mixer on the manifold trying to keep the UFH temperature within limits.

    I'd suggest running the boiler at a fixed low temperature (less than 50°C) that still meets the requirements of the UFH. The radiators may emit less heat than usual, but this can be compensated for by increasing the size of some radiators.

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