My combi boiler keeps losing pressure when the central heating has knocked off. Just using hot water it is fine. Can anyone help please.?


We have checked the radiator pipes to see if wet and all the joints on the pipe work, everything seems to be perfectly dry.

2 Answers

  • hooray
    Lv 5
    3 weeks ago

    As Girlie Electrics says, expansion vessel is a likely culprit. The diaphragm wears out after a few years. Sometimes the Schrader valve fails. How old is your boiler? The pressure relief valve might be the problem instead, or it could malfunction after operating in response to the expansion vessel failure.

    You're probably also losing pressure when you use hot water, it's just not as noticeable because heating places a much heavier demand on the boiler.

    Time to call someone out, you can't repair this yourself.

  • 3 weeks ago

    Failed pressure vessel or faulty pressure relief device.

    (Assuming there are no visible puddles around a radiator) 

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