the water runs hot and combi seems to be working fine but the central heating wont turn on thermostat turned up clock switches set to constant. it seems there are no flashing neons to indicate a fault and when i try to reset the boiler it goes back to how it was before

jassani, September 2011

When boiler cold and call for heat and boiler should fire, if not than is electrical fault and not calling for heat, check electric first.
OR If boiler fires on heat call and you have no heating than diverter valve is stuck to hot water side so you need replacing diverter valve

k, September 2011

firstly, when you say you reset your boiler and it goes back to how it was before, do you mean it works ok then or does it continue to be in fault condition?
Richard is right, that a common fault on the baxi (and some other makes) is that the hot water diaphragm can perish but, you need to give more info to get the right diagnosis cos, there are many faults on boilers with similar symptons. Is the hot water demand light on constantly?, if so it could be the hot water spindle stuck out keeping the microswitch on, if no hot water light on(tap symbol) then it could be your timer is faulty or your room thermostat is faulty.

Stephen, September 2011

the hot water runs fine its the heating that wont turn on

jassani, September 2011

Hi there is a valve inside the boiler that opens when you run the hot water and moves back when you stop running it to the central heating it sounds very much like yours is stuck. it is called the domestic hot water valve. you can buy a diaphragm kit off Ebay for around £7 or you couyld try a local plumbers for the kit. they are very easy and stright forward to fit.

Richard Scanlon, September 2011