Water hammer

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Hi
I've got a non vented system, and since I had the pressure release valve changed , when I turn the hot water tap on I get a very loud noise emitting from the cupboard when the tank resides
The valve has now been replaced again but I still get this load noise. It doesn't happen every time but it's so annoying.
 
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Well, you know that it's the ball float bouncing up and down, when it's down it lets water in which causes a shock that makes the ball come up and bounce again. what it needs is a baffle plate. what I did once was to screw a small piece of ally plate at right angles on a post so the plate was below the ball, just, and fastened the post to the ball arm with a jubilee clip. that baffled the bounce ability.
 
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I had a similar noise after my boiler was changed, I tried several things to cure it before someone (not my plumber - I had asked him and he just suggested foaming around the pipe!) suggested changing the tap washer. It was about 40 years old at this point and rock hard. Simple and cheap fix that anyone with a bit of nous can sort out.
It was misleading because the noise did not appear to come from the tap itself, rather somewhere back along the pipework.
 
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Thanks for your suggestion
I've installed a water pressure reduction valve, set this to 3 bar when cold water tap open, set the pressure tank to 3 bar.
I still get water hammering in the morning, like a machine gun going off.
My plumber has tried to fix it, but can't
 
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okay, more suggestions, a piece of pipe on the ball valve so the water enters under the surface of the water when it's nearly full,, Change the nozzle inside the ball valve to a red high pressure one which will reduce the flow.
 
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Hi
My header tank is shut off, i occasionally review it too check water levels.
This water hammering is worse first thing in the morning, and only occasionally happens during the day.
My plumber has tried his best even brought in another plumber nut no success
 
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can you reproduce this noise at will? can you see in the supply tank when this is happening? can you cut off the cold supply to the boiler ie is there an isolation valve/tap?
 
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Two plumbers have tried to find the problem,
It's to do with the incoming mains water pressure and the expansion tank pressure. The manufacture of the non vented tank state, " the expansion tank is forcing the water at a greater pressure than the mains water pressure".
The expansion tank is set at 3bar, and the water incoming pressure is set at 3bar with hot water flowing.
It's worse first thing in the morning, like a machine gun firing
 
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okay,, right, the mains water is connected to the boiler, you pump up the system, your boiler expansion tank, using the link to usually 1.5 bar, and then the connecting link to the boiler is shut off. no mains pressure water goes through the boiler. It only has the pressurised water you filled it with which circulates with a central heating pump.
The boiler heats your airing cupboard cylinder, which also has an immersion element in it, via a sealed coil of pipework within. no water from the boiler goes to the taps. your hot water comes from usually an attic cold storage tank, it enters your cylinder near the bottom and when you turn your tap on this releases water via the pipe on the top of the cylinder and goes to the tap.
is this your system, do you have a hot water cylinder, do you have a cold storage tank in the attic?
 
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Hi
It's a non vented system, only tank in the loft is a header tank to replenish the CH .
The expansion tank is set to 3 bar, the mains water is set to 3 bar when hot water is running.
 

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