the pilot is on.... the room thermostat are on max...hot water thermostat on the tank is max
yet no central heating or hot water !!
both were fine until yesterday; the only thing that was done was to reduce the temp on the hot water tank thermostat couple of days ago !

dev, May 2011

If the pilot light stays on, but the boiler won't light when you move the thermostat to position 6, then it is likely to be the gas valve. It is the most common fault, after the thermocouple.
In round figures the gas valve will be about £80 and the thermocouple [if you ever want one] about £10.
Plus VAT, but quote the RS number on the inside of the drop-down flap.

keidal, March 2016