andrewpreece wrote:


You would probably do best to locate the expansion reservoir doughnut (
possibly painted red, at the back of the combi, about a foot across??? ),
and see if you can pump it up via the bicycle repressurising valve. Then
keep an eye on the system pressure, maybe for several weeks. If the system
loses the ability to regulate pressure again, then it'll probably need a new
expansion reservoir, 'cause the daphragm will be leaking.

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.


--
Grunff