Is there a problem with my worcester 35CDi combi boiler?

sounds like a drop in water pressure when you have 2 taps open is affecting the divertor valve which then breaks contact with the hotwater microswitch and the hotwater neon goes out with the boiler following suit. if you think that the flow from the taps is as normal then the divertor valve will be suspect,usually last 5 yrs.worth checking if British gas do a fixed price repair of £156 in your area

combiking
March 2008