"John" wrote in message
...

"Phillip Brown" wrote in message
When I returned on Sunday, the thermostat had turned itself on as the
house was below 21-degrees, but the boiler wouldn't turn on. Nothing I
could do would make the boiler start up again. I have tried:

Replacing the thermostat

Why? did you by any chance test it and prove it faulty or just make a
guess?
Seriously what is your level of technical expertise in tracing a possible
fault?

Forgot to mention, the thermostat had been behaving strangely for a week
beforehand. E.g. the required temperature was set at 24-degress, the room
temperature was 25, yet the thermostat had not clicked 'off'. It is a
Drayton Digistat 3 and previous to this worked fine for a year. My logical
conclusion was therefore that the thermostat had given up the ghost and was
failing to turn on my heating system.

Testing the manual control of the motorised valve
Turning off/on all the switches on the timer
Checking the fuses to the main system and on the boiler's PCB

When the thermostat turns on, the valve opens and the pump starts,
however the boiler just does not ignite. It also does not make the
'humming noise' that you get for 10 seconds before ignition, which I
assume is the fan?

Is it possible the fan could be faulty, or is there some other
possibility between the timer (which works as it too turns the pump and
valve on and off) and the boiler?

I can't recall if this boiler has an overheat thermostat which requires
manually resetting. If it has find it and test it for being open circuit.

Could you point me in the direction of what to look for? I see nothing in
the manual about this.

In the past, when the water ran dry in my system, it did shut itself down,
but seemed to come back on after an hour, of its own accord.

Thanks for the ongoing advice.