Boiler sounds like a sinking ship!

[eyespy999]

Hi there

When my boiler is in hot water mode only it is making a rather load groaning noise which is periodic. When in heating mode it is fine.

I have recently flushed out the heating system and it runs like new except the hot water mode.

It is a system boiler.

Can anyone assit with a solution please?

Many thanks

 

[45yearsagasman]

Make and model?

 

[eyespy999]

Its a brittony chaffateux system plus 100.

Thanks for your help.