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  1. #1
    Automated Home Jr Member
    Join Date
    Oct 2016

    Question new to evoHome - existing Honeywell wireless room thermostat

    Dear all,

    Apologies for a lengthy post and probably some very basic questions.

    Being a little tired of the wrong part of the house being too warm or too cold respectively I have just ordered the Honeywell evohome WiFi Controller and the Honeywell evohome Radiator Multi Zone Kit (aka HR92s)

    My current boiler is a Worcester Greenstar Ri, and I believe the heating system is wired up as an S-Plan with two motorized valves, a wireless Honeywell Room Thermostat (CM727, and a dual channel timer for HW and CH. I have attached a photo for clarification. The cable coming on from the top right part of the photo comes from the timer.


    I have this idea that converting to Evohome might not be that challenging (that is if I want it to control CH only), but am going on a number of a assumptions and would be extremely grateful if someone could confirm or deny the below...

    From looking at my current setup I am assuming that

    a) my current setup is one, where once there is demand from the hot water cylinder thermostat or the room thermostat, the respective motorized valve opens, and the valve itself is then sending an on signal to the boiler + pump?

    b) My current room thermostat is already using a BDR91 as visible on the photo, which is the same box the new evoHome WiFi Controller can be linked to

    c) When I receive the WiFi Controller I can just take the batteries out of the old CM727 thermostat, follow the unbind procedure on the BDR91, and then bind the new evohome WiFi Controller to the existing BDR91

    d) That when I then further pair up all the HR92s with the new WiFi Controller I'm pretty much "done" as far as the CH goes - I can then switch the timer to "continuous", configure the HR92s as different zones, and if one of them drops below the set temperature it will operate the CH motorized valve through the existing BDR91, which will then turn on the pump and boiler through the existing wiring, in the same way it would have done so with the single wireless room thermostat - difference being it now does this "from every zone"

    e) That I do NOT configure the BDR91 as a boiler relay in evoHome, as it controls a motorized valve

    e) That I could, if I wanted, add another BDR91 to control my second (HW) motorized valve. That this new BDR91 would be linked up with a new CS92 transceiver that would in turn be connected to a CS92 strap-on sensor. I would have to follow the wiring from the current strap-on sensor (which is a Honeywell L641), which probably runs to the current junction box and controls the HW motorized valve. This would be disconnected, an instead the new BDR91 would be connected to that motorized valve.

    As I said I'm completely new to this. I hope this makes sense and would be extremely grateful for any answers.

    Please let me know if anything is unclear

    Many thanks - Martin
    Last edited by mart1711; 24th October 2016 at 10:32 PM.

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