Boiler kettling noise

[hansi]

My Glow Worm F55 boiler makes a kettling noise just before it switches itself off at the end of a cycle. No problem with the hot water or CH, just the annoying noise. Also my pump (Comet SMC 2-130) has three settings on it. I always have it on the first setting mainly because that is how it was when it was installed, but what do the other settings control. Ok, my boiler is 25 years old but is always serviced by BG annually and they always say it is in very good condition. Any suggestions please?

 

[Hugh Jaleak]

Kettling is due to scale or sludge build up in the heat ex, system may want a clean. Settings on pump refer to speed, 1 being lowest. While its still working I wouldnt worry, you're lucky. BG like selling new boilers!

 

[Keston]

dont know if it has a condensate trap but if it does check that for sludge also.

 

[hansi]

Kettling is due to scale or sludge build up in the heat ex, system may want a clean. Settings on pump refer to speed, 1 being lowest. While its still working I wouldnt worry, you're lucky. BG like selling new boilers!

Don't I know it! I'll ask the BG engineer if he can clean it at the next service.

 

[Hugh Jaleak]

Cleaning in this context means a powerflush of the pipework and heat ex in the boiler. Be aware AFAIK BG can charge up to £800 for this. Do you know if the system has inhibitor in it at the correct concentration?