Cold mains water hammer when taps are turn ON?

[Ian101]

The cold mains is in 22mm copper on a pipe run to to a bath and basin taps next to each other. The mains water is 4 bar static, no PRV or check valves. The bang happens seconds after the cold tap is turned on at either the cold bath or basin tap. There is a 0.5 litre potable water expansion vessel about 4 metres away prior to a combi boiler. There is a mechanical water hammer arrester 6 metres away close to the mains water stopcock. Don't want a PRV due to installation difficulties and the filter servicing required (very hard water). Given this, any ideas on the best way to resolve this please?

 

[Subby]

Clip all pipes correctly and lag them anywhere they are touching anything

 

[Ian101]

It's impossible to reach the pipe to clip at one section (an elbow joint). Do you know if a mechanical water hammer arrester, such as the Altecnic 525040, installed a few metres upstream would resolve this?

 

[Subby]

The shock arrestor should be fitted with a pressure reducing valve just after the internal srltop tap, or just after the first branch to allow full pressure at the first outlet (usually kitchen sink)

 

[Subby]

Altecnic also do a pressure reducing valve with a pressure gauge cheap as chips from plumb center or pts

 

[Ian101]

Thanks for the replies. Do pressure reducing valves require maintenance in a very hard water area?
Which make and model of adjustable pressure reducing valve is the most reliable, ideally fit and forget?
I don't mind pay out the extra for the reliability.

 

[cowdrayplumber]

I use Caleffi pressure reducing valves and I've never had a problem with them. I work in an area with hard water too.

 

[Ian101]

Thanks for the suggestion. I read the instructions for the Caleffi PRV here:
caleffi.com/sites/default/files/file/581035.09.pdf

Unfortunately, the instructions state the PRV cartridge needs cleaning at least every 12 months and a water hammer arrestor should be installed close by to prevent risk of damaging the PRV! Might be working perfectly for the first few years but several years later without being maintained, who knows. Does anyone know of a PRV that does not need to be maintained please? I believe there are some about but can't remember the manufacture name.

 

[ShaunCorbs]

There isn't one