Hi, our heating system (Baxi Combo 80e) has developed a fault. When we run a hot tap we get not very hot water, but the radiators heat up too! The LED display shows no fault. I have checked across the diverter valve microswitch and it has a 6v supply until tapwater demand, then the valve stem comes out and switches it off. The stem coming out would surely mean the valve is ok? Butl other forums say that the valve is usually to blame. The stem coming out puts doubt in my mind. Has anyone had experience with this fault? Many thanks.