Potterton Promax boiler making extremely loud noise?

[Ben Thurgood]

I have a Potterton Promax HE, and when I turn on just the hot water it is fine. However if I turn on the hot water and heating, after about 15-20 minutes it starts making a noise like it's going to bring the whole building down! I recorded a video...

Potterton Promax HE noise - Streamable

Any ideas what this could be? The heating itself works, but I have to switch it off after 15 minutes before this sound kicks in, as I don't want to do any damage to it.

Thanks

 

[ShaunCorbs]

Best to call a gas safe engy out or if your with British gas plan

Needs sorting / fixing

 

[king of pipes]

Gsri is needed i am afraid cheers kop