Rafal Kaczynski
Hi Anthony when you had your boiler installed? If not long ago and if it is still under guarantee please get in touch with installer to rectifie a problem. Rattling noise when CH is on it could be a cause of debris left in CH system due to poor instalation and commisionig. It can be exceed solder making that noise while pump is operating. Every boiler installation required flushing system before 1 st start so if they did not do it this is a problem. Get your installer back and do not pay him call out charge if he will ask for it. Hope this will help
