Worcester 20/25 heatslave not firing

Nice one Terry.

Might be worth adding that it is not uncommon for a fire valve to be fitted rated at 65c.

Most boilers require a 90c fire valve, so might be worth checking the brass valve body, where the temp rating is marked.
Looks like mine is 65c,
Boiler still not right ☹️... it is still tripping the lock out but now it does not trip the fire valve??
Seems to trip when high demand is on the boiler.. Anyone any ideas what to test now??
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Well that me up and running again, thanks to everyone that helped, much appreciated....

I now need to do two other small jobs on the boiler that I'm unsure of......
Any help /advice very welcome

1) I was told a while ago that the expansion vessel had water in it and needed to be drained and re pressured.
2) the auto air vent is leaking water and needs changing, I believe to change this the system needs de pressurised before doing this, how do I de and re pressurised the system

Are these jobs I can do myself or do they require specialist tools etc?


Boiler needs draining of water and drain valve left open whilst rest of heating circuit is isolated via shut-off valves, otherwise you'll need to drain whole rad system down to below boiler location. Then you pressurise vessel with air, using pump and gauge to MI specs (usually about 0.8bar). If it fails to hold that you'll need a new vessel. Also change auto vent whilst system is drained.
If it is locking out on the burner control, and the fire valve hasn't now tripped, it could be for a number of other reasons, all to do with the burner.

Fuel starvation is commonly to blame if it fails after a period of running.
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