Recent banging pipes

[Danno]

I live in a victorian house with a relatively old heating system (25 years or so) Heating/water have always been fine. Until recently.
During the colder weather we have turned the heating up and this seems to have caused constant banging noises through the night.(10minute intervals with around 20 bangs each time) Although they are not very loud they do tend to wake the family up. Banging seems to be coming from pipes rather than rads. Now we have turned the temp back down again the banging is still there?

Any ideas

Thanks in advance

 

[kevplumb]

boiler kettling

 

[Danno]

What is boiler kettling - and how can I remedy it?
Souds expensive?

thanks

 

[kevplumb]

kettling is localised boiling in the heat exchanger

try fernox restorer in a cartridge and inject it into a rad