Central Heating problem

[AnonymousImport]

I have a 19 years old central heating system with a Kingfisher Potterson boiler and been brillant until now ! When the Hot water come on after approx 10 minutes,there's banging noises which lasts about 2-3 minutes (not sure if it air or water) from the expansion tank via vent or feed pipe ,then everthing okay.I have change the motorized zone valve,pump and open up the by-pass valve still no different!.I'm now flushing the system with Fernox cleaner hoping to clear any possibly blockage etc.Some feedback from plumbers running out of idea!One suggested change the cylinder.Any idea ?
Regards
Andy Mason

 

[AnonymousImport]

I's got to be air mate,try connecting a hose pipe from the kitchen cold water mains fed tap,to the hot water tap,open both taps fully
,that will push the air out of the system.

 

[masona]

Thanks for the info,I took the boiler thermostats apart and blew out the dusts & hoover and turn the setting slightly down.It's now okay ! I think what happening, the boiler was overheating the water too quickly and therefore expanding to the expansion tank via the vent. I also turn up the pump setting to number 3 to speed up the water flow to reduce overheating. So far so good !

[Edited by masona on 11-01-2003 at 19:26 PM GMT]