Hi I have an Ideal c80ff combi boiler which the central heating comes on full blast even when its set for water only,it cannot be regulated and the only way to stop it is shut down completely. Its not like it all the time sometimes it works perfectly normal but when it does go mad its firing up every 2-3 seconds. I had a similar problem 2 years ago and the engineer replaced the PCB, the boiler is about 7 years old surely we don't need a new one!