Perplexing one - Replaced thermocouple on boiler after pilot went out.
Pilot will light and stay lit until running heating, boiler cranks up fine but after short while pilot and gas valve shuts off. Checked the thermocouple output (31mv), the overheat device is sound. The process can be repeated after short while, indicating the boiler temp has an effect (although system has not reached full temp before cuts out)
Programmer, Boiler and room thermostats are OK and Solenoid on gas valve operates OK.
I've run this with a meter on interuppter contacts thinking the thermocouple may be going open circuit when running, but it's ok, as must the overheat as it too would show as open. I'm thinking the electomagnet of the pilot control valve may be at fault - could it be anything else?
The gas valve is 6months old and the supplier won't replace on warranty as the pilot light appears not to be at fault, and the boiler starts, thereby they argue the valve is functioning OK
Pilot will light and stay lit until running heating, boiler cranks up fine but after short while pilot and gas valve shuts off. Checked the thermocouple output (31mv), the overheat device is sound. The process can be repeated after short while, indicating the boiler temp has an effect (although system has not reached full temp before cuts out)
Programmer, Boiler and room thermostats are OK and Solenoid on gas valve operates OK.
I've run this with a meter on interuppter contacts thinking the thermocouple may be going open circuit when running, but it's ok, as must the overheat as it too would show as open. I'm thinking the electomagnet of the pilot control valve may be at fault - could it be anything else?
The gas valve is 6months old and the supplier won't replace on warranty as the pilot light appears not to be at fault, and the boiler starts, thereby they argue the valve is functioning OK