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Retrofit for high temp radiators

Gene Davis_2
Gene Davis_2 Member Posts: 71
My heating pro installed in new construction, a heating system for the main floor of the 2200 sf main floor, and 2200 sf unfinished basement below, that is basically a one-temp system.

In addition to the underfloor PEX running in Wirsbo joist track plates, supplemental heat is delivered to some areas under large windows by means of Runtal flatpanel baseboard rads. Feed temp to these is the same as to the underfloor.

Boiler is a WM Ultra 80 propane with outdoor reset.

I'll ask him, but I thought I would ask here as well. What would be involved in doing a high temp to the rads?


  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    high temp rads

    Pretty simple actually. With the Ultra boiler there is a high temp or domestic water connection on the boiler as well as a heating call connection. You just need a priority circulator or ZV controller to run your high temp zones and DHW circ and connect the end switch to the DHW contacts on the boiler. When either the high temp or DHW zone calls, the boiler goes into priority mode, shuts down the heat demand signal and goes to pre-set high limit, them reverts back to normal operation when the high temp demand is satisfied. You can even use a two stage stat to bring on the high temp rads only when the radiant can't keep up.
  • hr
    hr Member Posts: 6,106
    that would be one way

    or determine the maxium supply temperature needed for the radiators. Run the boiler at that temperature via the OD reset feature (design temperature on design day only). Then either a dumb, 3 way manual, which would float with the reset curve, or smart mix down device for the radiant temperature.

    Before that I would run a room by room load calc to see where if any place the radiant falls short of the loads. Usually a combo of floor panel and rads handles most residential loads. If that is the concern?

    You can find output data for those rads online to add up the various emitter outputs.

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