So your boiler is making strange noises?
Unusual noises coming from your boiler is one of a group of key indicators that it may be faulty. If your boiler is usually quiet but suddenly begins making clunking, banging or knocking noises, it is time to call in an engineer. Such noises are often a sign that air has leaked into the system; however, they can also be caused by pump failure, a drop in water pressure or an excessive build-up of limescale.