Water hammer arrester but i dont have qater hammer

[stevethespreader]

Hi lads just had a new boiler fitted and they put a water hammer arrester under the boiler i started getting water hammer " ive never had this before" so i called them back and they cured the problem by taking the water hammer arrester off and said it was that which was causing the water hammer even though its supposed to cure it ive never had a water hammer arrester before and was glad that the hammering stopped but the company rang me back and said they want to fit another type of hammer arrester i said why? There is no water hammer so i dont need one, they said the boiler company warrenty is only valid if ones fitted im not sure if i sould let the put one in the one they are talking about fitting requires maintenance, to sum it all up they are insisting on an arrester but i dont have water hammer but if i dont the guarantee is void thoughts anyone? The boiler is a valiant 825

 

[CBW]

@ScottishGasMan might know this answer, I couldn’t see anything in the installation manual for the ecofit pure 825 or the EcoTEC plus 825, it mentions a system separator, which removes air.

 

[picasso]

It’s being fitted because in all probability you have a water meter or check valve on the water supply, it’s giving the expansion of the hot water somewhere to go, it should be fitted if the company want to install it.

 

[ScottishGasMan]

What Picasso said.

Any combi boiler fitted on a metered water supply, or any supply with non return valves in the cold feed system should have a mini expansion vessel fitted to prevent shock on the hydraulics and overpressure if preheat runs.