In message , ARW
writes
On 10/02/2019 20:40, Tim Lamb wrote:
In message ,
writes
On Sunday, 10 February 2019 19:33:38 UTC, Tim Lamb* wrote:

what would happen to a W plan system during a power outage?

everything stops & goes out, except the pilot light if a boiler has
one. What is the unknown there?
Er.. whether the thermal energy in the heat exchanger is sufficient
to overpressure the system with no circulation.

The pump overrun is there to remove the excess heat from the boiler.

The worst a powercut can do on a W plan is cause an overheat trip on
the boiler stat.

Hmm.. the only symptom of an issue was the unexpected zero pressure
reading. Fired up and operated normally without any other adjustments.



--
Tim Lamb