It is a condensing Combi boiler. British gas engineers say they need to call out the Worcester Bosch engineers, as the technology is a bit new to them.
The Booming noise occurs while the circulating pump is still running, but after the burner goes out when the room thermostat switches off...
A newly installed boiler from British gas, but they haven't come across this problem before. When the CH switches off on the room thermostat there are repeated loud bangs from the top of the boiler which last until switching the boiler off at the mains. Any ideas?