Banging/Clicking CH pipes

[str]

What could be the reason/cause for GCH pipes to bang/make a clicking sound?

This happens on only one of our upstairs radiators and only happens at 9.30/10 pm when the system has been on for 4/5 hours

Almost sounds like a leak dripping but this definitely not the case - stumped

 

[Diyisfun]

Its expansion & contraction

 

[str]

and the noise is due to the fact they have been fixed at regular intervals?

Nothing to worry about though?

 

[Diyisfun]

If I have hot water then the heating goes on, I get banging on 1 rad. If the hot water is not on & the heating goes on there is no banging.
What I like about it every moring at 6.30 is I know the heating is working.