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Thread: EvoHome S-Plan heating relay operates with HW demand

  1. #11
    Automated Home Ninja
    Join Date
    Aug 2016


    There's your problem. You don't have a BDR91 directly controlling the boiler - they're controlling your central heating and hot water valves. Boiler control should be none. Evohome is not (directly) controlling your boiler. The orange wires from your valves are.

  2. #12
    Automated Home Legend
    Join Date
    Sep 2014


    Quote Originally Posted by fysmd View Post
    Thanks DBMandrake, my setup is almost as you describe: I have replaced my old two channel timer with the two BDR91s and removed the old thermostat completely.

    The BDR91s are wired to the valves as you say and the orange wire from each is cabled to boiler demand.
    Surely if I bind both into hot water, I'll only get heating when there's hot water demand? I'm confused.
    Yes you are.

    From the pictures you posted later on you have your system set up incorrectly - you have added a boiler control relay when you shouldn't.

    In the stored hot water configuration it will ask you if you have a zone valve for both hot water and heating, say yes to having both valves.

    Then it will ask you to bind in order - hot water sensor, hot water relay, central heating relay. This is where you should be binding the central heating relay NOT as a boiler control relay, which must be set to none.

    Fully clear the bindings on both BDR91 with a 20 second button press then set boiler control to none and stored hot water to none to clear all the relay bindings at the controller end.

    The go into stored hot water and follow the prompts to bind hot water sensor, hot water relay and central heating relay.

  3. #13
    Automated Home Lurker
    Join Date
    Dec 2017


    O - M - G !! I feel so stoopid!

    Yep, I've followed the instructions (properly) now and have proper control over both heating and water valves.

    A MASSIVE thank-you to everybody for helping me sort this out.

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