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Thread: Evohome controller multi comms faults.

  1. #21
    Automated Home Legend paulockenden's Avatar
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    Quote Originally Posted by Drpepper View Post
    Interestingly a couple of evo certified installers have now both told me that as I have HR92s on all but two rads (recommended at time to ha e two without), there's no point having the CH valve at all and the BD91 should be wired directly to the boiler for demand as the HR92s control the opening and closing process at a rad level.
    That would only be true if you had HR92s on all of your rads (and an ABV).

    Without them, if you did as you've described, you'd have those rads coming on every time your hot water tank needed a top up, even on a sweltering hot summer day.

    P.

  2. #22
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    Tbh as they are in an open plan utility room and a downstairs WC that don't need separate heating as they get it from surrounding space I'm pretty sure they are turned to close.

  3. #23
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    My dual controller Evohome system was part of a full replacement of boiler, rads (around 26, I forget the exact number), and all pipework - I chose to keep the zone valves for simple reversion to a non-Evohome control system and so that I could more-easily see what was happening. The delta cost was trivial and the only downside seemed to be that there are a couple of additional points of failure (although 2-port valves seem to be very reliable compared to the 3-port, Y-plan, valves).
    Why remove valves that are already fitted, especially when not all your rads are being controlled?

  4. #24
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    Yes, a valid point to be fair.

    Reason one would be the CH one has failed so at least needs a new head, second would be one installer is telling me there's no point having them and another is telling me I shouldn't have them.

    Obviously the original installer thought there was a point. These differing opions are all from evo home certified installers which doesn't help. It will probably come down to who can get round first to sort it tbh.

  5. #25
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    Hmmm, the one "certified evohome installer" that I dealt with was worse than a waste of space.

    If you want to try operating without the C/H zone valve before deciding whether to replace the head or not (<30) then lock it open and use the BDR91 output to drive the pump and boiler directly. I haven't done this but I presume you just bridge the brown and orange z.valve wires - check the diagram in the Evohome book.

  6. #26
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    Quote Originally Posted by DorrisMancer View Post
    Hmmm, the one "certified evohome installer" that I dealt with was worse than a waste of space.

    If you want to try operating without the C/H zone valve before deciding whether to replace the head or not (<30) then lock it open and use the BDR91 output to drive the pump and boiler directly. I haven't done this but I presume you just bridge the brown and orange z.valve wires - check the diagram in the Evohome book.

    This is what I did with my setup, Locked the CH valves open using the manual switch on the valves, electrically isolated them and had the BDR91 fire the pump and Boiler

  7. #27
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    It does seem to be an installer lottery... Anyway I have one that has a good rep lined up he's just busy as its that time of year.

    I'll have a read of the manual tomorrow and maybe try that, or as we have the home emergency cover with the house insurance I may try and get someone out that way. They probably won't know Evo but presumably could interpret the manual or at the very least replace the head on the valve as an Interim.

  8. #28
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    Just made the modification above, manually opened CH switch, locked it and isolated electrics on it.

    BD91 for the CH now firing boiler direct. I also changed boiler demand in the system config from 'none' to 'boiler relay' which I assume is correct given the mod.

    I'm not going to have the valve taken out as if the system ever went back to none Evo that would prob again be required (granted likely with a new head).

    So far so good anyway......

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