Persistant banging

[Mato]

When the radiators are on every minute or so i have a banging noise that lasts for about ten bangs.... more like a dull thudding than a bang but annoying none the less. It starts fast and by the tenth has slowwed to a halt.
It happens consistantly while the heating is on and can be timed with a stopwatch.
Is it expanding pipes? Trapped air?..... Help.

 

[Polly1]

As far as I understand it, that's your pipes expanding and the noise is probably the pipe against the joist under your floor or wherever the pipe is pressing against wood.

It is possible to cure this problem by stuffing something soft & heat resistant between the pipe & the wood.