Help with kettling boiler

[Giles]

Hi, I am new to this group and am not a plumber or any good with DIY infact so be gentle with me please! I have recently moved to a 6 year old house with an Ideal Classic FF boiler that suffers from kettling once warm. I have had 2 plumbers look at it, 1 said the system needs pressurising whilst another just advised as I live in a hard water area to put a bottle of Sentinel x100 into the header tank. After a bit of research I thought the Sentinal option would be the less painful. I poured a litre of x100 into the header tank but really can not see how that will circulate through the system? So the question is do I just sit and wait for it to circulate or do i have to do something to force the water from the header tank in to the system? As another supplementary question was the first plumber trying to rip me off? Thanks for any help and advice. Giles (Leics)

[Andy Hall]

You would need to check with the boiler manufacturer as to whether it can be made part of a pressurised system. Some cannot and are only suitable for open vented arrangements. In any case, I am not sure that it would improve kettling.

There is value in having a corrosion inhibitor in the system and that is what X100 is. However, it is not intended to do anything about kettling.

A noise reducer such as X200 might make an improvement.

It will eventually because as the heating water expands and contracts with heating and cooling, there will be some mixing.

The normal procedure with liquid corrosion inhibitor additives is to turn off the mains water or tie up the ball valve, then drain off about 10 litres of water from the drain c*ck. Add 80-90% off the additive to the header, then turn the water back on to fill the system. Finally add the remaining inhibitor. For a noise reducer you could add the lot in one go and top up.

It's worth having a sealed system if you can - refer to Ed Sirett's Sealed System FAQ referred to in his signature.

[Giles]

Thanks Andy, I appreciate the information and advice. Giles

[Andy Burns]

Pressurised water will have higher boiling point, therefore less likely to suffer localised boiling in the pipes/boiler.