boiler clanking

[craig1]

Hello,

When the boiler has been fired up for half an hour it starts making

a banging/clanking noise. I then switch the boiler off, and then back on

again and the clanking stops. could anybody tell me what causes this and

how I may rectify this problem.

Thanks.

 

[Bahco]

Could be air, or you might not have a bypass fitted or opened enough.