Loud noise from cold feed...

[Tony 1234]

pipes,

How do we stop it, I altered part of the feed now it's banging like hell.

How do I get the air out?

[B17NNS]

Sounds like water hammer.

Are all the pipes clipped firmly in place?

Try adjusting the pressure slightly at the stop cock or on any isolating valves where the banging comes from.

When does it happen? after flushing the loo? running a tap?

Is your system gravity fed or all mains pressure?

[Simpo Two]

Did you change a stopcock from high (mains) to low (gravity-fed) pressure?

[Tony 1234]

Sorted now (thank you) air came out of the taps in the end