DIY Doctor UK DIY Forums

Hi all,

I Have a Biasi M90F Combi Boiler that has developed an unusual problem. The CH works fine but, when the CH's set to summer mode and the hot water tap is turned on the radiators heat up to the highest temperature :shock:

If I completely turn the CH part off, the the hot water will not work at all.

Any Ideas before I call a plumber...?

Cheers in advance

diverter valve/microswitches most commonly,possibly the domestic heat exchanger could alos be blocked allowing water round the rads ,but more than likely the microswitch/diverter valve