Noise unvented hot water

[jsb]

Hi,
We've got a problem with our unvented Range Tribune hot water system. Quite often when we turn on a hot water tap we get a loud banging and then quite often a moaning sound - almost like a diggerydo! - for a few seconds. We have a PRV in the garage reducing the incoming pressure to 3 bar, though reducing this to 2 bar makes no difference.

When we initially turn on a hot water tap there is a high pressure rush of
water, then the bong/banging/moaning happens after which the water pressure drops significantly. The plumber who installed the setup has said that the bong/banging noise is due to the non-return valve in the combination valve which makes up part of the Range Tribune installation, but replacing it has made no difference. The moaning appears to come
from under the bathroom floor!

Any ideas? Could it be loose pipes? How often should the pipes under the floor be clipped?

Thanks

 

[BLOD]

Check the pressure at your bathroom hot tap & drop the pressure of your expansion vessel to slightly below that - hopefully the noises should stop

 

[jsb]

Hi Blod

Should I measure the pressure at "normal" pressure or in the evening when the noise occurs and the pressure seems to be higher? The plumber's already changed the expansion vessel once and has set the pressure to 3 bar like the PRV on the mains inlet to the house.

I've tried to attach a zipped wav file containing the noise but it's just over the 100 kb limit but can email it to anyone interested (or who wants a laugh ).

Cheers

 

[Jeet]

Hi Blod
Have you found the cure for this embarrassing noise, As I too am suffrring from the same I Have a service contract with National company and its like banging your head against the wall they have tried all the above and lot more to the point where they are refussing to attend to the same problem.

Help
Jeet

 

[Gray0689]

Had this problem with range cylinder before it was sorted by changing the flexi hose to expansion vessel to hard copper

 

[jsb]

Range themselves send out an engineer who solved the problem by reducing the pressure on the expansion vessel connected to the hot water cylinder from the normal 3 bar to approx 2 bar.

Hope it works for you!

Jonathan