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Thread: Evohome Help Please.

  1. #1
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    Default Evohome Help Please.

    Upgraded installation of Evohome with UFH- HCC80R + extension, DT92 thermostats per zone, HW using tank and CH upstairs, all radiators with HR92's. The original installation was an "S" plan system. The pipe to the UFH has been joined to the "T" point after the original CH motorised valve. There are two BD91's one in HW circuit controlling the original motorised valve for that and one controlling the other CH original motorised valve. The UFH pipe then travels through house until it gets to another new motorised valve followed by the controller and pump for the UFH zones.
    How should this be wired and bound? Is the plumbing correct? Do I need the CH motorised valve at all? Should I have a BD91 for the boiler?

    The boiler is an Oil fired unit non combi.

    Thanks for any help you can give me.

  2. #2
    Automated Home Ninja Dan_Robinson's Avatar
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    That's a disaster of an installation.

    Get rid of the heating zone valve and bind the bdr to be heat demand.

    It's all in the manual.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  3. #3
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    also I don't understand why the UFH circuit is after the CH Valve. You then effectively can't run your underfloor without your upstairs being on. Like Dan said, since your entire CH is now under the control of Evohome get rid of all the CH zone valves both rad and UFH. One BDR91 should fire the boiler the other should operate the HW valve. That's it.

  4. #4
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    Quote Originally Posted by bruce_miranda View Post
    also I don't understand why the UFH circuit is after the CH Valve. You then effectively can't run your underfloor without your upstairs being on. Like Dan said, since your entire CH is now under the control of Evohome get rid of all the CH zone valves both rad and UFH. One BDR91 should fire the boiler the other should operate the HW valve. That's it.
    I hear what you say and I am obviously an amateur here, but without CH valves won't the pipes all get hot when the HW comes on? I realise there's no flow but having no CH valves sort of needs thinking outside of the box for an oldie like me.

  5. #5
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    no where to go = no flow.

    So if Evohome has all the CH devices off the water isn't going to flow anywhere in the CH circuit. So no, even the pipes won't get hot beyond about a centimetre or two past the first T.

  6. #6
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    Quote Originally Posted by Chrisnoy View Post
    I hear what you say and I am obviously an amateur here, but without CH valves won't the pipes all get hot when the HW comes on? I realise there's no flow but having no CH valves sort of needs thinking outside of the box for an oldie like me.
    When You take away the Existing CH Valves and replace with HR92s you dont have no Central heating valves as you say you actually have one CH valve for every rad so they will be closed if no CH Demand

    So HW can heat without heating Rads

  7. #7
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    Quote Originally Posted by mylesm View Post
    When You take away the Existing CH Valves and replace with HR92s you dont have no Central heating valves as you say you actually have one CH valve for every rad so they will be closed if no CH Demand

    So HW can heat without heating Rads
    Yep, I see it now, thanks to all for this advice, very much appreciated.

  8. #8
    Automated Home Ninja Dan_Robinson's Avatar
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    Good luck dude.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  9. #9
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    Maybe I've misunderstood the answers, but what's so wrong with a zone valve on the C/H? I have 3 zone valves: one for DHW and one for C/H (both controlled by BDR91s) and one for towel rads (currently controlled by a 7 day timer, see my earlier question about how to bring this under evohome timer control)

  10. #10
    Automated Home Ninja Dan_Robinson's Avatar
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    The hr92 unit is effectively a zone valve in its own right.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

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