Related because its interesting.

Having achieved SOME stabiliy by not using one ring at all, suddenly the
damned thing was tripping again and I managed to get it consistent
enough to narrow it down to the system boiler.

Engineer came, and it didnt trip. Pump was OK BUT he took the cover off
and said 'tracking inside - waters been dripping in - well I knew that
there was a leaking gate valve by the pump, that weeped at high
pressure, and I had suspected the pressure vessel, since pressure change
hot tpocold was rather higher than i remembered... sure enough when he
hit the schrader valve, out came water not air.. So new gate valve and
pressure vessel in today and that's the next issue done with I hope.

So the failure mode was :

pressure vessel diaphragm=over pressure=blown gland in gate valve =
water in electrics = RCD trip.

It's like being in government after years of Labour this house is.
Everything has been left and not fixed or bodged.

Thats what comes of marryng an art student with mental issues...


--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.