Hi. I have a Baxi 105E that when the central heating comes on all is ok for 5 - 10 minutes, then the central heating light goes off and the hot water led starts flashing. The fan is still running. As i don't have a manual i can't check what fault this is. The hot water & heating pressures are all ok. If i turn the hot water pre heat all the way down to off, the heating works ok but obviously the wife moans when she has a wash then. Cant win. Any help would be gratefully received.