The boiler is approx 4 yrs old. Both heating and water worked fine until recently when the heating has packed up all together. This hasn't affected the hot water at all.
I've tried restarting boiler, display shows (c) for a few seconds then shows (d) which is the hot water. The heating still does not come on. HELP!

a desperate woman :(, April 2012

if you have a dripping tap, even a slight drip, this will cause the boiler pre-heat to activate and you get no heating. make sure no taps are dripping first off, if still showing 'd' the turn off the cold water supply to the boiler, if you get heating after that then you may have a leak somewhere on the hot water pipework. i know it sounds daft that a drip will cause this, but this boiler uses the hot water temperature sensor to detect if a tap is running and even the slightest amount of water running causes this.

Ian, April 2012

Might sound a bit obvious but have you checked the water pressure gauge is 1.5 bar usually underneath these boiler small round gauge showing pressure

Bal, April 2012