Hi. Help please. Central heating ok but no hot water. On h/w mode the pump runs but can't hear the boiler fan and burner does not light. No fault lights showing just the green light to confirm h/w mode. Water pressure and flow is fine. The pins on the diverter valves pop out ok and as far as I can see the microswitches ok. have tried over riding them by connecting the wires together but this makes no difference. Am I right in assuming that the pcb is faulty? If I take off the temp sensor wires the panel shows them as faulty so I am assuming they are ok