Evohome HR92s not sending demand for heat.

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  • rvb99
    Automated Home Sr Member
    • Oct 2017
    • 74

    #16
    Your set up seems a little confusing. The heating bdr should be bound to the evohôme which it seems it is as the ufh comes on and the boiler fires.

    Now for the upstairs .Is it that the boiler does not fire or that the pump does not run or that the zone valve for upstairs is not opening .

    Does the bdr come on when the upstairs HR92s call for heat? If yes then it seems to be a zone valve or heating pump wiring problem .

    The fact that upstairs only comes on when the ufh heating is on suggests perhaps they are sharing the same zone valve and possibly the heating pump. However, The ufh most likely will run without the heating pump as the ufh internal circulating pump will draw from the heating circuit ( mine will but I still switch the heating feed pump with the boiler) . So as you say it’s probably the heating pump not switching.

    If the zone valve for upstairs is opening then the pump should be switched , either directly from the bdr or via the relay output on the upstairs ( +ufh?) zone valve. Ie when the valve is open one of the relay wires ( orange - but check ? ) becomes live and can be used to switch the pump ( and also the boiler in the case the boiler is not directly wired to the bdr)
    Last edited by rvb99; 8 April 2018, 12:14 PM.

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    • Ozzx
      Automated Home Jr Member
      • Oct 2017
      • 10

      #17
      Sorted now! Thanks all for the help. It was actually a faulty zone valve actuator, when I opened it up I found that some of the teeth on the motor cog were broken which stopped it from fully opening and the switch never activated to send the demand to the boiler. I replaced the zone valve actuator and all is working perfectly :-)

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