A boiler installed by dodgy plumber with lack of electrical knowledge 2 yrs back in my sisters house has been cutting out from the outset after some tapping noises. Will run if turned off for a while. Suspect overheating due to incorrect wiring? Pump overrun? Does anyone know where to download a wiring diagram for this system? Mabe you know what the problem is? Any sudgestions? I am a knowledgable electrician but do not live near my sister and dont work usually on boiler systems!