ok - Boiler working c/heating & hot water work together - hot water does not work on its own. New honeywell room thermostat fitted & New honeywell is it control box in boiler room + New 3 way valve. All seem's ok untill I turned room stat down - as it reached room temp which I assume would turn boiler/heating off the main heating fuse tripped out. Resett the fuse and now the Heating works but the hot water does not and if I select H/water only on the control the light flickers on/off. NB if I select h/w and c/h both lights are on as they should be although the h/w does not heat up. Can you offer any advice ? sure hope so. cheers j