Grunff wrote:

And if the diaphragm is totally buggered, when you push the pin on the
Schrader valve water will **** out, right? And this means there is no
expansion space, so the pressure relief valve blows every time the
boiler fires. Got it. We need a new expansion reservoir. Many thanks for
the detailed explanation.

If it is the diaphram, you may find it simpler to just add another
expansion chamber elsewhere, rather than trying to get at the original one.

--
Cheers,

John.

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