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Thread: Evohome in new build house with 2 zone and HW

  1. #11
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    Quote Originally Posted by JamboV6 View Post
    Back from holiday now so would like to get this sorted in the next week.
    Could i not wire the two heating valves to the boiler BDR91 or would that pull too much current?

    with regards to the HW t/stat are you saying to use the danfoss one instead of the probe supplied with the honeywell kit or use it in parallel additionally?

    thanks
    You Could do this but you make no mention of an ABV so when boiler demand ceases Zone Valves close but pump still runs on overrun so would be deadheaded without ABV

    If the Zone Valves were Locked open then uncontrolled Rad acts as Bypass during Pump overrun

    The simplest thing to do is just open Zone valves manually and disconnect electrically as Dan said not being fully open should not cause a problem but if you like do as i done take the heads off Zone valves and then open them fully as if the motor had opened them and leave in this position much easier than physically removing them

    If you want to leave an uncontrolled Rad I would be more inclined to leave a Towel Rail rather than the Hall you can set temp for hall and it will be maintained by HR92 but a toasty ensuite or Bathroom is nice

    As I understand the Existing HW Stat gets wired in series with new Stat so if New Stat Fails then Original Stat will still operate and cut Boiler Demand
    Last edited by mylesm; 16th November 2017 at 06:25 AM.

  2. #12
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    Quote Originally Posted by mylesm View Post
    You Could do this but you make no mention of an ABV so when boiler demand ceases Zone Valves close but pump still runs on overrun so would be deadheaded without ABV

    If the Zone Valves were Locked open then uncontrolled Rad acts as Bypass during Pump overrun

    The simplest thing to do is just open Zone valves manually and disconnect electrically as Dan said not being fully open should not cause a problem but if you like do as i done take the heads off Zone valves and then open them fully as if the motor had opened them and leave in this position much easier than physically removing them

    If you want to leave an uncontrolled Rad I would be more inclined to leave a Towel Rail rather than the Hall you can set temp for hall and it will be maintained by HR92 but a toasty ensuite or Bathroom is nice

    As I understand the Existing HW Stat gets wired in series with new Stat so if New Stat Fails then Original Stat will still operate and cut Boiler Demand
    Thanks for your reply,
    The system does have an ABV
    The reason for keeping the utility uncontrolled is because of the size and shape of it and the radiator it doesn't matter if it heats a bit more often but also I want to be able to set the towel rail as and when independently to other rads.

    Surely the T/Stat probes need to be in parallel, if. They are in series and one goes open circuit it will leave the probe circuit open. If In. Parallel and one fails the other will still work

  3. #13
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    Quote Originally Posted by JamboV6 View Post
    Thanks for your reply,
    The system does have an ABV
    The reason for keeping the utility uncontrolled is because of the size and shape of it and the radiator it doesn't matter if it heats a bit more often but also I want to be able to set the towel rail as and when independently to other rads.

    Surely the T/Stat probes need to be in parallel, if. They are in series and one goes open circuit it will leave the probe circuit open. If In. Parallel and one fails the other will still work
    They need to be in series, therefore if one fails (so leave the circuit closed) once the cylinder heats up the next stat in the series will open and cut off the heat source. The way you are describing would prevent this from happening.

  4. #14
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    Ofcourse, wasn't thinking about it being a normally closed circuit. Nightshifts and jetlag don't make for logical thinking

  5. #15
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    So I ordered all the parts last night, just need to work out the wiring, please see attached image for my current setup.

    final parts list was;
    -main wifi control inc BDR91
    -13 x HR92 rad valves
    -hotwater kit inc BDR91
    -wall mount kit
    -extra trv valve body
    Attached Images Attached Images

  6. #16
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    Have you made a decision re Existing Heating Zone Valves are you keeping them or not

  7. #17
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    Yeah, i'm gonna do what you suggested, isolate and remove the motor and manually crank them fully open.

  8. #18
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    Well Looking at your wiring centre I would remove All wires going to Tp5000 and Tp9000 and red Plug and yellow plug

    Also remove orange wire blue plug from terminal 10 and Grey wire Blue plug from Terminal 2 and place both in terminal 7 which is now a spare terminal this will remove HW Zone Valve Demand

    Terminals 1&2 are Live and Terminals 3&4 are Neutral on your wiring centre

    SO In Your New Boiler Demand BDR91 wire L to 1 and N to 3 and wire A to L internally in BDR or to Terminal 2 in wiring Centre and B to Terminal 10 which is SLB (Switched Live Boiler)

    Your New HW BDR wire L to 1 and N to 3 and A to L internally or Terminal 2 in wiring centre and B to Terminal 8 which will put this BDR in series with orignal HW Stat and Terminal 9 will still Drive HW Valve

    I am assuming Green Plug is original HW Stat and OT Protection and Terminals 1&2 and 3&4 are fed from a suitable fused spur but check all this and make sure to turn up old HW Stat to max as it will now only be used as safety backup to new BDR which is reacting to Evohome HW Demand
    Last edited by mylesm; 21st November 2017 at 01:17 PM.

  9. #19
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    Fantastic, that couldnt be any easier, thank you.

    So wire it like this heating wiring evohome.jpg

    If i wire the honeywell tank stat in series with the original would this be correct heating wiring evohome 2.jpg


    Thanks again for all your help

  10. #20
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    Hot water kit arrived today, so I'm guessing my second drawing is wrong and the evohome stat that is wired to the cs92a wirelessly transmits to the control panel that then tells the bdr91 to switch? Is that correct?

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