The boiler keeps heating the radiators even when I have switched to hot water only. Sometimes the only way I can prevent this is to turn the boiler off completely. It frequently locks out and the reset light goes red. I have already had the boards replaced and the diverter valve replaced

PH, October 2009

flow switch stuck on, boiler thinks you have a hot water demand so fires up and cos there isnt a tap open it goes round the radiators =) replace hw flow switch, few quid, power off, cold water off, hot tap open pull wiring connector off and unscrew sensor, new one in, tighten, wiring back on, water back on, observe for leaks, power back on.

ste, October 2009