Pressurised plumbing system noise

crazy600

Previous post
"Has anyone any ideas?
I have this loud groaning noise coming from the area of my pressurised hot water cyliinder, which includes expansion vessel.
I had this problem a while after this new system was put in, had many plumbers look at it, and there only sugestion was to move the grunfos mq pump to the ground floor(it was orig in attic with cylinder) and turn expansion vessel on its side.
Did this, with much expense and hey presto problem gone! now 6months later the noise is back again (it would wake the dead). help please"

Changes made to system - still have the noise - HELP
The plumber changed the temp/non return valve, which is between the pumped mains water and hot h2o cylinder from spring type, to open shut valve type, he moved the cold water to also go through the non return valve. Now I have the noise on both the hot and the cold.
He checked the cylinder temp to make sure it was'nt cooking and it's fine, he also checked the pump to make sure there was no dirt blocking the line. He has run out of ideas. I'm at myy witts end. The only other suggestion seems to put a pressure reducing valve before the non return which we could try to throttle down and see if it makes a difference.
The pressure was checked in the potable water expansion vessle and it is 3.25, plumber could not get it to 3.5bar.
Suggestions anyone

crazy600

How close is the expansion vessel to the cold supply for the cylinder.

crazy600

approx 3ft distance 4ft pipe work
UTube Video of instillation:
http://www.youtube.com/watch?v=lwf8yP0rigk

crazy600

Sorry Gary71 misunderstood question.
The expansion vessel isapprox 34ft from pumped mains supply, before the changes when we first had the noise it was only 2-3 ft from pumped mains

That could be you're problem, it's good working practises to have the expansion vessel as close to the cold feed to the cylinder as possible, what can happen is as the pressure is released from the cylinder after you open the hot or cold then the pressure stored in the expansion vessel can generate a noise as it is released, that resonates along the pipe between the vessel and the cylinder. Gary.

crazy600

Sorry Gary71, I'm a complete dipstick, it's my origional answer, 3-4 feet between the expansion vessel and cylinder, the pressurised feed comes inbetween the xpansion vessel and cylinder but on the same line

The noise is a pressure issue, sometimes I find that it's to do with a higher pressure on the cylinder side repeatably forcing the non return valve back on it's seating causing a vibration or the other culprit is as in my other post the position of the expansion vessel and if there is air trapped in the water side, having looked at the clip the only thing I could advise would be to tee in close to the clinder on the cold feed and connecting close to the tee with the expansion vessel, your mains looks like it's pumping towards the vessel which in it's self can be a problem. Where is the Temperture/pressure discharge pipe going to from the cylinder? also have you tried opening it to make sure the water doesn't back up and flood the place, Gary.

crazy600

gary71 wrote: »

The noise is a pressure issue, sometimes I find that it's to do with a higher pressure on the cylinder side repeatably forcing the non return valve back on it's seating causing a vibration or the other culprit is as in my other post the position of the expansion vessel and if there is air trapped in the water side, having looked at the clip the only thing I could advise would be to tee in close to the clinder on the cold feed and connecting close to the tee with the expansion vessel, your mains looks like it's pumping towards the vessel which in it's self can be a problem. Where is the Temperture/pressure discharge pipe going to from the cylinder? also have you tried opening it to make sure the water doesn't back up and flood the place, Gary.

The Temp/pressure discharge pipe from the cylinder goes into a tundish which is piped out of the eaves and it does work thanks. I know now it should discharge into a shore, but there is no shore near it in the side entrance. You reckon it might be worth trying moving the expansion vessel closer to the cylinder so? as I siad we on't have too many ideas left except move!

Have a look at the expansion vessel position in this link http://www.telford-group.com/downloads/files/Installguide_tornado.pdf

When the cylinder is heated it will increase the pressure in the pipe work, the nearer the expansion vessel is to the cylinder the less likely pressure is a problem, also it's very important to make sure the vessel fills with water, if you give yours a tap you should be able to tell if the water side is full, Gary.

crazy600

Thanks Gary, gave the expansion vessel a few taps, sound like there's no water there at the moment. Is that normal? or should it always have some water.
Think I'll give a go moving it to right beside the cylinder before any draw off.
Plumber is back on monday so I'll let you know if that works

Air in the water side of the expansion vessel can make a noise as it leaves the vessel when the pressure drops off, This is repeated if the air cannot clear it's self due to pipework design. The expansion vessel should be filled water and full sounding on the water side.

crazy600

Finally, replaced the whole expansion vessel, pipework and valve with a new kit, much more straight forward pipework, seems to have done the job at last!! all quiet for 1 week now.
Fingers X it doesn't come back in the future.
Thanks to Gary for all the help.:)