raden wrote:
....
Best first to check that the solenoid isn't open circuit


The solenoid is indeed open circuit. When it's switched on, it has 240V across
it, but nothing happens.

I learned that Honeywell do replacement operators (solenoids) for their valves.
Details at
http://content.honeywell.com/uk/home...s%20Spares.pdf

I expected that to be a cheaper solution than replacing the entire valve
assembly, and a lot easier.

Ed Sirett wrote:
....
The valve used is a multifunction unit.
It comprise the thermocouple valve, pilot supply, solenoid valve and
gas pressure regulator. The operating solenoid is integral with the whole
valve.

After the main valve (likely £50-100) is replaced you would adjust the
pilot flame and set the burner pressure to that indicated on the rating
plate then confirm that the gas rate is 90-105% of the intended rate.

Thanks for that. How is gas rate measured? Also, how is the pilot adjusted?

Regards

Edwin.