We had a Saunier Duval boiler installed a year ago and it's been nothing but trouble. The latest thing is that the pilot light goes out and you can't reset it unless you turn it off and on again at the mains. The repair guys can't find a fault with the boiler, and it's not the thermostat. What can it be?

sjh2008, October 2008

Thanks Woodspeed - I guess by pilot I mean the green ignition light. It's a XEON model, brand new a year ago. We've had the engineers to look at it about eight times, they can't find a fault and have replaced two circuit boards and the little door over the control panel, but it's STILL switching off, and will not restart unless turned off at the mains, then on again. The engineers now insist it must be an external problem. Does that sound possible?

sjh2008, November 2008

Only fitted a year ago and it has a pilot????? Boilers for years have had electronic ignition.
However: maybe a s/h or older unit?
There is a heat sensor on the pilot - thermocouple. This may be faulty or not aligned in the flame properly. Part is £10-£15. May not be sealed properly in which case it can blow out. Fan can fail or stick, in which case it shuts down. These devices are for protection.

Woodspeed, October 2008