My dad has just replaced the valve which switches from hot water to central heating. He checked the system was working when he had finished and apart from one radiator it was fine. The system was left on but by the time I got home an hour later the boiler was out. 2 questions:-
Any ideas what might have caused it?
How do I light the boiler again I can't see a normal ignition switch?
Any help would be gratefully received as my poor dad has worked all day on this and I could do with solving this one myself.