Many thanks again for your help - it's much appreciated.
I've now adjusted the pressure and the gauge is now sitting nicely in the green at about 2, however the same problem remains. Boiler fires up when I turn a hot water tap on but the CH is not working. As soon as you turn the hot tap off...
Hope someone can help.
I've had my current boiler for three years - no problems with it at all, until yesterday when it didn't fire up in the morning. I flicked the reset switch a few times but nothing, so I left it planning on calling an engineer later on. But five minutes later it came on...