reducing burning time and pipe banging

[vasehedar]

After switching on the central heating switch, the boiler would fire up and burn for about 2min and stop. The second time it fires up. it would only burn for about 1min while the third time it would only manage to last for about 30 seconds before stopping. This reduction in burning time would continue until it would burn for about 20 seconds before stopping. Beside the problem, the pipe seem to bang quite loudly from time to time (very unpredicatble as to when it starts to bang)
Does anyone know what is causing the reduction in burning length and solve the banging pipe problem?

 

[Stod]

Sounds as though your pump's not working.

 

[oilman]

See this