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Thread: UFH - EvoHome and reluctant plumber

  1. #11
    Automated Home Lurker
    Join Date
    Aug 2018
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    Yes it was rvb99's first approach that best fitted my situation as the manifold came with electric actuators. I totally agree about the sense in keeping manifolds, pumps and wiring centres accessible and I had the luxury of siting it in a full size cellar beneath the space in question. Only problem was that the boiler is three floors above necessitating a long heat shielded connection via the CH pipework. Evohome was fitted some time after the UFH was installed. The floor is flagged so it took a bit of juggling with the schedule but now the spaces concerned are consistently dead right.

  2. #12
    Automated Home Legend
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    Jul 2014
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    985

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    if the entire manifold is serving one heating zone, then electric actuators are completely unnecessary. They are only needed if individual runs are serving different rooms, which can be shut off from others..

  3. #13
    Automated Home Lurker
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    Sep 2018
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    I have a single zone twin loop UFH setup controlled via Y87RF and BDR91 in my new well insulated extension. BDR91 activates the pump and manifold valves are left open.

    As itís in combination with 26 rads, there is a thermostatic mixing valve to reduce the flow temperature. Boiler is Intergas HRE40 SB with OpenTherm module, and an outdoor sensor (unfortunately weather compensation doesnít work with Evohome OpenTherm support though).

    Iím not happy with the UFH setup for a few reasons:

    1. The mixing valve intermittently emits a high pitched whine, appears to be when the flow temperature matches its set point.
    2. Wife complains about 1!
    3. Poor temperature control. Evohome indicates a 40-60% demand for the zone even when the set point is reached, as a result there is an overshoot. Optimum start typically pre-heats for 1.5 hours, temperature increases to more than 1 degree above the set point after a few more hours, still with <20% demand, then optimum stop kicks in 1 hour before set back. Iíve tried reducing the mixing valve set point temperature but Evohome seems unable to adapt.

    Primarily because of 2, Iím going to replace with an HM80 controlled rotary actuator and flow temperature sensor. I hope this will work better with OpenTherm and provide more accurate temperature control.

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