Have put a multimeter across the pilot gas valve and get 240v across the main gas valve I get only 2to3 volts but the black wire to earth is 240volts and the white wire to earth is 240 volts

Jean, February 2009

Look through the little window and check the pilot flame is heating up the thermocouple tip properly. It should be all around the tip. If it's not hot enough or if the thermocouple tip is burnt away, the gas valve will not allow gas to the main burner. Mine burn out every 18months in an Apollo 60/80. £7 at a plumbers merchants, but you shouldn't dismantle the boiler unless you know what you are doing. ( I've kept mine going for 26 years, only that b----y thermocouple goes wrong!)

BryanL, February 2009