Fitting water hammer arrester.

[Spedley]

My 3 bar water tank is upstairs and my shower and tap are about 20 metres of 15mm copper pipe away from it. The shower seals were made for 1 bar maximum but they seem to cope fine with 3 bar but just can't manage the water hammer effect from the sink tap turning off quickly.

Rather than replace the shower (remove tiles and extra plumbing etc) fitting a water hammer arrester will probably fix the problem but should I put it near the tap or the shower? The tap is at the end of the pipe and the shower is tee'd off 3m before that.
I doubt it will make much difference but I'm just checking.

 

[bobasd]

you raise a few questions butyou'd be better off gettin in a plumber who can take various an accurate psi's across the installation. an maybe chose a bestposition for a pressure reducin valve PRV an see if the tap is fit for purpos.

 

[John D v2.0]

should I put it near the tap or the shower?

should be on the leg of the appliance causing the issue i.e. the tap. but with 20m of 15mm in the system anywhere at that end would help! that is a lot of mass of water on the move.

 

[Spedley]

Thank John, that is pretty much what I thought.

 

[hard-work]

Fit it near the offending tap, as been mentioned. It will protect many brassware fittings.

If you have 1 bar rated brassware with 3 bar pressure, and it is holding out, then it will eventually leak or you are in luck with it holding out. When on hols turn off the mains stoptap and release pressure just to be sure. Don't want to return to a domestic lake.

 

[Spedley]

Good advice, thanks! It's only a temporary measure until I have more time and money to do a proper job and replace it but that'll probably be nearer Christmas. We do have another shower so I could just leave it but this is my favourite!

 

[bobasd]

just sayin but

strikes me as the above posts aregivin the op uncertain advice about bein specific where to fit a arrestor.
as far as i now 3Bar is to much for any part of any domestic system.
we dont know the pipework layout an the sink could be akitchen sink or abasin in a bathroom.
could even be down to a faulty tap?

if the arreator was fitted near the tap then
unless the showervalve has a psi limiter whats protectin it?
dont s/valves most have a 1.5bar limit?

an now the op mentionsanother shower - what else is branchin off?

20m = 65ft , thats a long run in a house?

 

[John D v2.0]

3 bar is pretty normal for a domestic mains supply. true vented would be a lot less, well under 1 bar though

 

[Bodd]

It could be as simple as replacing the incoming main stop cock

 

[bobasd]

your right about the 3Bar being normal or as common as lower pressures.
i was talkin rubbish.

it could be the incoming stop cock but it could be a few other things.

 

[AdrianUK]

A PRV can do nothing about the static pressure (no flow). It can only reduce the dynamic pressure (ie. when the water is running).

You could also try an 'old school' water arrester - a length of vertical 28mm pipe with closed end (the trapped air acts as a shock absorber). Water hammer can exert alot of sudden force, the 'kick' can easily be several 10's of BAR if the stopping of the flow is rapid enough.

 

[hard-work]

A PRV can do nothing about the static pressure (no flow). It can only reduce the dynamic pressure (ie. when the water is running).

You could also try an 'old school' water arrester - a length of vertical 28mm pipe with closed end (the trapped air acts as a shock absorber). Water hammer can exert alot of sudden force, the 'kick' can easily be several 10's of BAR if the stopping of the flow is rapid enough.

Air eventually disolves in water pipes. Shock arrestors are cheap enough.

 

[hard-work]

just sayin but

strikes me as the above posts aregivin the op uncertain advice about bein specific where to fit a arrestor.
as far as i now 3Bar is to much for any part of any domestic system.
we dont know the pipework layout an the sink could be akitchen sink or abasin in a bathroom.
could even be down to a faulty tap?

if the arreator was fitted near the tap then
unless the showervalve has a psi limiter whats protectin it?
dont s/valves most have a 1.5bar limit?

an now the op mentionsanother shower - what else is branchin off?

20m = 65ft , thats a long run in a house?

In many cases two shock arrestors may be needed, or one big arrestor (expansion vessel).

 

[picasso]

If you want a prv that controls the static pressure fit a "drop tight" prv, Honeywell do5 or similar.

 

[bernardgreen]

I was reminded about this post I made a few years ago. The device is still working ( but not on my machine )

For a washing machine a home made arrestor will normally suffice

.

After time the trapped air will have dissolved into the water. Then close the isolator, loosen the connection to the washing machine hose to drain the water out of the 22 mm section. That replaces the trapped air cushion.