HELP! This happened about 8 wks ago - switched heating on and sudden loud crashing and banging noises throughout house with shunting of pipes - boiler experts suggested 'kettling' due to new pump needed. When they came pump worked fine so suggested flushing out system at a cost of £500!!! I declined! Pump work for about a month then same thing happened. Called different pumber who replaced pump. Worked for 7 days and again crashing and banging with this awful shunting of pipes. Electrician came to check in case 'short' was happening somewhere. Nothing wrong with electrics pumps started up again. For 3 days!! If anyone out there can help with this I would be so grateful. Have bled the radiators and there was a lot of air in system. Should I now be getting the system 'flushed'?