Hi, have a 2 year old Baxi HE boiler which has been a nightmare from day one with air noises in the boiler that no one (even Baxi) seems to be able to sort out. Last winter I had alot of noise from pipes in the house aswell but had lots of work done to create space around the pipes and that is now alot better. One main problem remains. When the boiler switches on the central heating there is a couple of noises like a thud or a crack in the pipe leading to the lounge radiator. What could this be, does anyone have any ideas? Am happy to give more details if this will help.