My central heating/water pipes are banging when the boiler comes on. Do we have an airlock in the system and if so, how can we stp the banging?

If this only happens when boiler is coming on from cold then it sounds like the problem is loose pipe work and potentially an air lock. Bleed all rads and the pump and any air bleeds any where else on the system when the pump is not running, Have a look at what number the pump is on as this could be forcing the system causing water hammer. The pump ideally wants to be on number 2. Then check for any loose pipes around the pump and in any floor voids and secure as needed. If the banging/rattling is happening when its been running for a while then it sounds like the boiler is 'Kettling', this is caused by the boiler over heating. You will need an engineer to check over your system to make sure all stats and system controls are working ok.

Hi, I'm not a plumber by trade but know my way around a heating system. Your problem is usually caused by loose pipework within the floor space, air in the system can make the noise worse, call a plumber in. Kind regards Paul