can anyone help? the pilot light keeps going out when i use the hot water,it runs fine but when i turn the tap off the temperature goes to 70 c and knocks the pilot off. it works fine when the central heating is on. the system is about 14 years old.

john, April 2009

Could be a Scaled Hot Water Heat Exchanger

Boiler Repairman - Ipswich, April 2009

check pump over run, if water not circulating the overheat stat will keep kicking the pilot out, also check the operation of the the diverter valve and micro switch if this is sticking and not shutting of the boiler will be firing still and no water ciculating, boiling the water

STE, April 2009