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Worcester Bosch Greenstar Danesmoor System Boiler 18/25 Oil fired

Discussion in 'Plumbing and Central Heating' started by ajpen207, 22 Jun 2021.

  1. ajpen207

    ajpen207

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    We are trying to work out what is wrong with the boiler pump which continuously circulates water even when there has been no call to heat the rads or water. We have checked the external thermostatic controller which is working correctly and is correctly wired up. The zone valves are also working normally and are correctly wired up.

    The only way to stop the pump is to turn the whole boiler off at the isolator switch on the wall. We are thinking it is an internal thermostatic issue within the boiler itself but cant see how to check the probe end of the thermostat.

    First post here so apologies if this is in the wrong forum. Any tips would be great. Many thanks in advance. : )
     
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  3. JohnD

    JohnD

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    Have you got a motorised valve something like one of these?
     
  4. ajpen207

    ajpen207

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    Hi
    Thank you for responding. Yes we do and both of them open and close as we would expect. The circulating pump on the boiler keeps going even when the wall thermostat programs for hot water and heating are off. The only way to stop it is to turn the whole boiler off at the isolator switch.
     
  5. oilhead

    oilhead

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    If you refer to the installation instructions, there is a link between the live feed and the pump connection for use in certain applications. Depending on your controls this may need to be removed. Do you have a frost stat? This may be causing the problem if not wired correctly.
    Is this a new installation? If so get the installer back.
     
  6. BoilerBob

    BoilerBob

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    Good call mate could be frost stat u/s. Bob
     
  7. ajpen207

    ajpen207

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    Hi All

    Turns out it was a weird electrical fault with the motorised valve for the hot water. Somehow it was causing the pump to circulate even when the boiler and hot water controls were off. We have fitted a new valve and the pump, boiler and thermostat are now behaving normally for the first time since the boiler was fitted.

    Thank you to all who responded
     
  8. oilhead

    oilhead

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    As the end switch in the valve powers both the boiler and pump, then the boiler must also have been firing.
     
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