Loud banging when central heating comes on

[saddler78]

Hi.
My central heating system makes a lot of loud banging noises when it comes on and goes off. Lasts for about 15 minutes when it comes on but then very little noise until it goes off again. Any ideas?
Thanks

 

[45yearsagasman]

Any Ideas? With so little other info, don't expect much help.

 

[buck51]

First guess, would be expansion and contraction of the pipes

 

[Homesafe]

Second guess, weak pump
Third guess, air lock
Give more info like system sealed or not will help .