If i blow into the APS (via restrictor) the boiler lights up, heats and runs for about 5 minutes but will not start again even when the room thermostat or hot water thermostat is calling for heat. I know the central heating pump is working and the boilers fan seems to be going strong.
I suspect the mid position valve (MPV) is faulty as recently i found that the radiators only get hot if i am calling for hot water and the MPV is set on manual.
I would like to get the system working prior to signing up for a British Gas care plan.

Any ideas?

Steve Brown, November 2008

Hi Matt, The fan only starts when i blow into APS now. The system was making HW via timer ok but no CH unless as i said the MPV was in manual position - as soon as HW tank was full, call for CH was no longer firing boiler. I have used Glow Worms troubleshooting guide in the manual and that says the cable harness or connections to fan are faulty but i know thats not right because if i blow into APS 240v appears on the fan wiring - but not before i blow into APS. Can the MPV hold the system off if its faulty?
Thanks in advance
Steve

Steve Brown, November 2008

why are u blowing into the aps if the mid pos valve is faulty ?? if the fan is running the boiler is being told to fire

matt, November 2008