Kettling is quite an old fashioned term which was originally used to describe literally a "boiling up,bubbling"noise which could often occur in old boilers. The old Ideal-Standard wall hung boilers suffered with it quite a bit. The problem seemed to be caused by the fact that the actual casting could have a some small "holes" or crevices inside where a small amount of air would get trapped and cause the noise. The noise could transmit through pipework.
Your problem could just be air in the heating system which would normally be most apparent when trapped in the pump. You would not call this kettling. Everything on your heating system needs to vented throughly inc. the pump. with it all off. If you have got noisy hot & cold water pipes thats a whole different problem. Good Luck!
David, October 2010
