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Thread: OpenTherm Operation

  1. #1
    Automated Home Lurker
    Join Date
    Oct 2019

    Question OpenTherm Operation

    I have recently purchased and installed Evohome system. I just wanted to check my understanding as I believe the system is not operating as it should.

    On the controller, if there is heat demand on the OpenTherm (on the summary page) should the boiler fire up. Originally when setting this up, I set up two zones and checked the operation. So when a zone called for heat 2-3mins later the boiler fired up. I completed the installation, and when checking this morning some of the zones are calling for heat but the boiler has not fired up. On the controller the heat demand for the Open Therm bridge is at 100%, as are the other zones. I checked the signal strength and all was OK. Is this normal behavior, as I would expect the boiler to fire every time there was demand, just trying to think is the cycle time had been exceeded or something?

    It could also be due to my configuration as my boiler (Worcester high flow) does not have OpenTherm so I am using an adapter . My next question is, since I am using a adapter to convert OpenTherm to ETS protocol, I am wondering if it best to fit a normal wirless relay on instead. The boiler will modulate heat as required, would this be a better option to explore if my current setup is not correct?


    Combi boiler (Worcester Highflow)
    Evohome controller
    OpenTherm Bridge
    14x HR92 valves

  2. #2
    Automated Home Legend paulockenden's Avatar
    Join Date
    Apr 2015
    South Coast


    If the boiler / heating loop is already up to temperature it won't fire - it'll just keep circulating the water until the temperature drops. Could that be it?

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