Noise from unvented hot water system

[ianmcd]

Regin Stirrup pump, comes with a 3m hose, had mine for years now, just the job for high up UV EV's and on the wall boilers. Some say their's failed in no time but looked after mine's at least 5yrs old now.

I had three diaphrams burts in a matter of months, ended up taking the long hose off and fitting it on my rechargeable compressor, been like that for about six years now

 

[Madrab]

I had three diaphrams burts in a matter of months, ended up taking the long hose off and fitting it on my rechargeable compressor, been like that for about six years now

Aye, that's just too much spinach and those Popeye arms of yours

Was it the stirrup pump that burst the diaphragms? Gauge not right then I guess or was something else?

Checked the calibration of mine with the bike tyres against a proper pressure gauge and it was within .1 bar, maybe I was lucky.

 

[ianmcd]

Aye, that's just too much spinach and those Popeye arms of yours

Was it the stirrup pump that burst the diaphragms? Gauge not right then I guess or was something else?

Checked the calibration of mine with the bike tyres against a proper pressure gauge and it was within .1 bar, maybe I was lucky.

yes the stirrup pump burst, lad at Parts centre just laughed when I took them back, he showed me through the back with all the ones he had to return, must have been a bad batch, Lidl sold the exact same one under a different name for £9.99 I think it was, my mate bought one and still has it

 

[George Isles]

Really appreciate the help here, plumber has promised me a call this afternoon!

Looking at your setup, you do not have balanced cold feed from that combination valve

what would a balanced cold feed look like?

When i stand right next to it with my hand on the EV it sounds like its come from in the EV tank but plumber tells me it could just be reverberating in there from water hammer caused elsewhere........

What is puzzling is it worked fine for a year until we had a new bathroom fitted and he did loads of work on the system, I cant isolate the new shower and bath though as they dont have isolators on!!

From everything that has been said here air trapped on the water side which is causing a pressure build-up during heating might be the issue.....i have timed it the last few mornings and it is a consistent 7 seconds from turning the shower to when the noise occurs and the noise lasts about 3 seconds.....if only i could post a video of the noise!!!! I do get the noise from other outlets at othet times of the day but not as consistently or as badly.

 

[Agile]

Looking at the photo I see its a 22mm pipe feeding a short flexible tube.

When I see such a low resistance route to the EV I always expect a noise issue.

My first try would be a long flexible tube and if that fails then to replace the 22 mm by quite a long 15 mm section.

 

[DP]

The white plastic pipe, does that go to the new bathroom?

While I do not think it will make any difference, what you can do is slacken the nut at the end of the flexible pipe below the expansion vessel and let any air out which will escape as air bubbles- when water starts weeping out of the connection, tighten the cap nut. DO NOT UNDO THE nut completely. You will flood the place

The combination valve I suspect is set for 3.5 bar. When you draw water from the cylinder and then Close the hot tap, cylinder pressure will be at 3.5 bar too if water is not being heated. Overnight into the morning no water drawn and cylinder is being heated. Cylinder pressure will be higher. It would seem the noise is occurring while until the pressure of water in the cylinder is at 3.5 bar.

There are instances where there can be a dead leg ( length of pipe with trapped air) which causes combination boiler to delay operation and shutdown. If such a slug of air is the issue, then try what I have suggested above.

 

[DP]

what would a balanced cold feed look like?

When i stand right next to it with my hand on the EV it sounds like its come from in the EV tank

When you look at the combination valve, there is a cap nut with a blank in it. That is where the cold feed would normally be taken so that both hot and cold are at the same pressure

Try what I suggested at different points in the system and listen for the strength of noise rather than presence as you are looking for the source. Noise will travel through water and plumbing but source will be the loudest

 

[George Isles]

I reckon you might have hit the nail on the head there….prior to the new bathrooms there were no mixer taps and the shower feed passed through an old pump which I bet acted as a non-return valve….now we have 3 mixer showers and 5 mixer taps throughout the house none of which are fed off the PRV!!!! Problem I now have is all pipework is concealed by tiles/wooden floors/new carpet!!! If I fitted a PRV to the incoming water feed before any of the mixers are connected would that have the same effect…reduce/regulate the whole system to the same pressure?

 

[dilalio]

I reckon you might have hit the nail on the head there….prior to the new bathrooms there were no mixer taps and the shower feed passed through an old pump which I bet acted as a non-return valve….now we have 3 mixer showers and 5 mixer taps throughout the house none of which are fed off the PRV!!!! Problem I now have is all pipework is concealed by tiles/wooden floors/new carpet!!! If I fitted a PRV to the incoming water feed before any of the mixers are connected would that have the same effect…reduce/regulate the whole system to the same pressure?

Yes. You can fit a reducing valve to the cold feed to balance it with the hot. Not ideal but done properly it will work.

 

[DP]

One of the problems with high mains pressure and UV cylinder along with mixer taps is that high cold pressure can slow or reduce hot water flow from cylinder. Not heard any noise though from cylinder with this issue

 

[Madrab]

Ideally you want all mixer taps fed from the balanced mains from the combi valve but my experiences suggests that isn't what's causing your issue. I have come across the the dreaded drone from a cold system all fed from a balanced feed and it was an issue at the EV, and that was even on a brand new EV. A chattering 1/4 turn valve can cause a similar noise but that's usually heard at the outlet and not back up at the vessel.

Even an over pressurisation from a passing mixer with the mains higher than the PRV setting I don't think would cause the drone at the EV, that would more be an issue with dripping at the tundish

Have you depressurised the cylinder and filled it a few times, sometimes that can shift it.

 

[DP]

Ideally you want all mixer taps fed from the balanced mains from the combi valve but my experiences suggests that isn't what's causing your issue. I have come across the the dreaded drone from a cold system all fed from a balanced feed and it was an issue at the EV, and that was even on a brand new EV. A chattering 1/4 turn valve can cause a similar noise but that's usually heard at the outlet and not back up at the vessel.

Even an over pressurisation from a passing mixer with the mains higher than the PRV setting I don't think would cause the drone at the EV, that would more be an issue with dripping at the tundish

Have you depressurised the cylinder and filled it a few times, sometimes that can shift it.

Rab, what you describe was in issue at one clients cylinder. New combi valve sorted the problem
He had balanced cold supply.

 

[Madrab]

Yup, had that one a couple of times too @DP, though with me it was a different kind of droning noise when it was the PRV that would change when it was adjusted. Swapped it out and nice and quiet again.
The EV noise seems to be a very distinctive drone/honking sound IME and it seems to be the same no matter what system it is. I've always found it was to do with the EV and/or it's piping. Once it was because the EV was on the hot side and it looked like it was catching air bubbles when the system was heating. The drone started when the hot tap was opened after a period of non use and the cylinder fully re-heated. There was a little surge of pressure when the HW tap was opened as the pressure was passing from the EV into the pipework, the HW outlet would sputter a little then settle. Changed it to the cold side and dropped the EV height and it stabilised and shut up.

Not necessarily what's happening here of course but it would be my place to start for sure.

 

[George Isles]

As an update on this one plumber finally came back 2 weeks ago. Fitted a shock arrestor…..did nothing to help. He demounted, drained and depressurised the EV, pumped it back to 3bar and refitted it…..Bingo no noise…..until yesterday when the noise returned….same pattern as before, makes the noise when the hot is run after the hot water heater has been on. My latest theory is that as the water heats and the pressure on the balloon forces it up against the air cushion it is getting stuck there until there is enough of a pressure release for it to fall again, this would explain the 8-10 second lag between opening the water outlet and the noise occurring. Any thoughts?

 

[Johntheo5]

If it's a Glendhill Lite then do a search in Plumbersforums.net.