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Thread: Switched to evohome & caused damage to boiler?

  1. #11
    Automated Home Legend paulockenden's Avatar
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    But note that if it's on your normal heating loop it'll only work as a bypass if:

    a) all of the other rads have HR92s or whatever, and most importantly:

    b) you don't have a CH valve, or else somehow (mechanically or electrically) you keep it open whenever the boiler is firing or over-running.

    P.

  2. #12
    Automated Home Sr Member
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    I'm the same as dty - I have 3 towel rails that are partly open plus an 'over run' in the garage which (usefully) heats a radiator there.

  3. #13
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    I have a similar boiler and the bathroom rad has no temperature regulation gadgets fitted so the boiler has always something to do.

    Plus sometimes evohome can run your boiler in error and rather than just the boiler groaning in the middle of the night with the bypass valve open it can do something a little more useful and quiet.

  4. #14
    Automated Home Sr Member
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    To think it could all be solved if you could set the hr92 to a minimum open level. Also a delay in switching radiator valves off so the boiler can do it's overrun. I would love to be able to set the hall and bathroom to a minimum of about 5% each.

  5. #15
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    Quote Originally Posted by robj20 View Post
    To think it could all be solved if you could set the hr92 to a minimum open level. Also a delay in switching radiator valves off so the boiler can do it's overrun. I would love to be able to set the hall and bathroom to a minimum of about 5% each.
    The problem is that the HR92 has no practical way of knowing if a given valve position actually results in any flow or not. DBMandrake will be along shortly to explain his theories about the relationship between the HR92 reported valve position, the actual valve position, the deadbands at either end and how they relate to flow, and how the whole lot relates to boiler demand.

    3... 2... 1...

  6. #16
    Automated Home Sr Member
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    Quote Originally Posted by dty View Post
    The problem is that the HR92 has no practical way of knowing if a given valve position actually results in any flow or not. DBMandrake will be along shortly to explain his theories about the relationship between the HR92 reported valve position, the actual valve position, the deadbands at either end and how they relate to flow, and how the whole lot relates to boiler demand.

    3... 2... 1...
    You could easily as part of an advanced setup have the valve operated manually from closed open until you have flow and set one step back as 0%

  7. #17
    Automated Home Jr Member
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    So I understand the idea of a bypass radiator...

    What I'd really like is a different bypass rad according to the time of day...

    I currently use the smaller of 2 radiators in the main room, and the larger one rarely 'opens'. This is OK for daytime.

    What I'd really like is for it to switch to the rad in my eldest's bedroom at night. During the day her bedroom is set to 15C (she's at school), and we keep the door closed (this alone is going to save me a fortune). However, at night the thermostat is constantly calling for heat (and thus the downstairs room is kept unnecessarily warm).

    Any thoughts on an automated way of achieving this? Say main room from 7am to 11pm, and bedroom from 7pm to 8am?

    Actually, I think I can do something with some HR20s. Or is there are better programmable TRV someone could recommend? I heard some people suggest Terrier i-temp i30s.
    Last edited by zxdavb; 8th February 2018 at 12:37 PM. Reason: added a question at the end

  8. #18
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    What we appear to be suggesting is an additional setup criteria per zone that either creates or not a boiler demand. Now that we have an electric zone type that does precisely that, has any one actually tried to see if an HRxx will bind with such a zone type?

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