I recently went through the fault analysis in the manual as i was having problems with my combi and through all the tests i did came to the conclusion that the pcb was Knackered so i went out and bought a new one and installed it.It still wouldn't fire up and so i checked various other things which seemed to be wrong and sorted them out,evereything seems to be fine now apart from the gas valve will not open. The fan fires up and is working fine, the pump is working fine,the pilot is working lovely,the room thermostat is fine, but the gas valve just will not open. The modulater is getting the correct voltage and seems to be working fine, the gas valve though does not seem to have any power going to it. If i take 24v ac and connect it to the gas valve it does work, but this is not right as i shouldn't need to re-wire on a new board, also when the heating goes of with this arrangement it doesn't cut off completely and the gas still comes through although the flames are really tiny, and the pump and fan are still working fine. I wanted to know if anyone out there knows if the fault lies with my new pcb or if i need to check something else as something is preventing the relay on the board from swithching the 24v ac onto the gas valve. Please help as i am desperate.
- posted
19 years ago