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Openthem and pump long run times

Discussion in 'Plumbing and Central Heating' started by ^woody^, 3 Jan 2021.

  1. ^woody^

    ^woody^

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    I've had a new combi boiler controlled by Opentherm (Drayton Wiser) for a year now, and something really niggling me is the apparent long time that the boiler pump is running. It can literally be running for hours non stop some days.

    Apparently the theory is that the boiler is made to run for longer at a lower temperature, and avoid constant cycling. Also apparently, there is more wear in on/off cycling than in having the pump run continuous for long periods.

    Can anyone put my mind at rest that long pump run times are normal for Openthem?

    Also what is a pump's lifetime expectancy, under almost continuous running compared to cycling. Am I worrying unnecessarily about early pump failure from this continuous running, or would the manufacturer have allowed for it?
     
  2. muggles

    muggles

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    What boiler do you have?
     
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  4. ^woody^

    ^woody^

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    Baxi 830
     
  5. muggles

    muggles

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    Ah, that may be your problem. The Baxi range is well known for being rather temperamental on OpenTherm. I believe it plays reasonably well with Nest, but not so well with some other controls. Baxi might be able to offer a firmware upgrade if you call them, but I don't know whether the issue has actually been resolved yet.
     
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  7. muggles

    muggles

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    Here you go, found a relevant bit of info from someone who knows. Essentially Baxi have used some bits of the OpenTherm communication protocol to provide control, but they aren't members of the OpenTherm Association and haven't fully implemented OpenTherm in the way it was designed. Baxi boilers aren't OpenTherm certificated. Ergo, they only work with Usense and Nest.

    Baxi not OT.png
     
    Last edited: 3 Jan 2021
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