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Thread: Help with S Plan 3 BDR91 Wiring

  1. #1
    Automated Home Lurker
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    Default Help with S Plan 3 BDR91 Wiring

    Hi all,

    I currently have an Evohome setup and my heating is an S Plan config. I'm looking for help confirming the wiring for adding a 3rd BDR91 controller into this setup in order to take advanced of some of the newer features in the latest beta software. These features aren't available when BDRs are only configured under the stored hot water config. The setup that I'm trying to achieve is

    BDR 1 - Boiler Control
    BDR 2 - Central Heating Zone Valve
    BDR 3 - Hot Water Zone Valve

    I've attached a diagram I edited from the Evohome manual but I wondered if someone could confirm that it's correct or point me in the right direction.

    BDR_WiringDiagram.jpg

    Cheers
    Spence


    I've just noticed that the image size seems very small, here's a link to a high resultion version.

    https://photos.app.goo.gl/tnuZ2cRa6cfDtEMF7
    Attached Images Attached Images
    Last edited by spence189; 7th December 2020 at 08:40 AM. Reason: Added link to photo

  2. #2
    Automated Home Legend
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    Sep 2014
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    Scotland
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    2,322

    Default

    Quote Originally Posted by spence189 View Post
    Hi all,

    I currently have an Evohome setup and my heating is an S Plan config. I'm looking for help confirming the wiring for adding a 3rd BDR91 controller into this setup in order to take advanced of some of the newer features in the latest beta software. These features aren't available when BDRs are only configured under the stored hot water config. The setup that I'm trying to achieve is

    BDR 1 - Boiler Control
    BDR 2 - Central Heating Zone Valve
    BDR 3 - Hot Water Zone Valve

    I've attached a diagram I edited from the Evohome manual but I wondered if someone could confirm that it's correct or point me in the right direction.

    BDR_WiringDiagram.jpg

    Cheers
    Spence


    I've just noticed that the image size seems very small, here's a link to a high resultion version.

    https://photos.app.goo.gl/tnuZ2cRa6cfDtEMF7
    At a glance that looks like the correct diagram.

    If you already have a two relay system with the relays operating the hot water and heating zone valves all you're essentially doing is disconnecting the orange wires from the zone valves and substituting the output of the 3rd relay to the same point that goes to the boiler - it is taking the place of the microswitches in the zone valves. (I would also be inclined to disconnect the grey wires on the zone valves for safety reasons as there's no need for them to have switched live 240v going nowhere even though they should still be terminated in an empty terminal block)

    Once you've wired it up just go into boiler/appliance control (depending on firmware version) and bind the new BDR91 and you should be up and running. I did the same as you when I moved from an already working 2 relay system to a 3 relay system.

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