Jeff, I had this problem last year and it eventually gave up the ghost and the safety cut out kicked in. I called Glowworm technical support and after spending a fortune on various diagnosis from an air pressure swith to a new control panel, I decided to pay the 195 pound call out for the Heatcall engineer. The call out includes any spare parts and would have been money well spent if I had just called them out in the first place. The problem was the diverter valve which had seized with lime scale. Hope this helps.
Regards
Rob
Rob, May 2006
