Boiler Kettling?

[Jerry1]

My boiler makes a hissing sound similar to that of an electric kettle, is this what is referred to as kettling and how can this be cured/minimized.

i have a vented system with a f/e tank in the loft, i have recently replaced a zone control valve and am in the process of bleeding air out of the system - the pump gurgles and churns every now and then, and in particular when the hot water is first turned on

The HW circuit was drained then filled after replacing the valve, no chemicals were replaced - should there be a fernox protector in there? would a lack of this chemical be related to the kettling/boiling noise due to there just being plain water boiling in there as opposed to a chemical mix with a much higher boiling point? The whole thing started after refilling the system.

Am in the process of investigating the possibility of air leaking into the system via expansion pipe, but i am unsure of the cause of the kettling/boiling sounds

Any help would be mostly welcome - thanks

 

[Softus]

My boiler makes a hissing sound similar to that of an electric kettle, is this what is referred to as kettling and how can this be cured/minimized.

Yes, and you can reduce it by descaling the boiler.

i have a vented system with a f/e tank in the loft, i have recently replaced a zone control valve and am in the process of bleeding air out of the system - the pump gurgles and churns every now and then, and in particular when the hot water is first turned on.

Are you finding that you have to keep venting? Is so, then I would suspect either air being pulled in, or corrosion in the rads.

The HW circuit was drained then filled after replacing the valve, no chemicals were replaced - should there be a fernox protector in there?

Yes - Fernox MB-1 or an equivalent product.

...would a lack of this chemical be related to the kettling/boiling noise due to there just being plain water boiling in there as opposed to a chemical mix with a much higher boiling point?

Unlikely.

The whole thing started after refilling the system.

Am in the process of investigating the possibility of air leaking into the system via expansion pipe, but i am unsure of the cause of the kettling/boiling sounds

Any help would be mostly welcome - thanks

I still think it's scale.

 

[Guzzles]

I've just descaled my boiler. Symptoms very similar to yours. I used Fernox DS-40, but isolated all the radiators to minimise leak risk. Ran the Ds-40 for 24 hrs (using plenty of hot water to keep tghe system in use) Once neutralised, and fully flushed, I added Sentinal X-100 and X-200 which I'll leave in. All the noise has dissappeared, and the bolier is not tripping like it did.

 

[Jerry1]

Thanks for all the help - have added a descaler to the system, ran it for 24 hours drained it and added a protector.
noise has disappeared - problem solved
thanks.

 

[Softus]

Thanks for letting us know - it's always good to get feedback.