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Discuss Cylinder noise / Balanced Colds / Pressure etc in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

Poiuytr

Messages
24
I wanted to start a new more dedicated thread as I am on about 3 just now in one way or another trying to get up to speed with my problem. The issue is that my Gledhill Stainless Lite indirect unvented cylinder makes loud noises when heating - this is a bit random, but that noise is loud enough to startle and sounds like a mix of a metallic / plastic bang. The noise seems to occur more often when the hot water has been drawn down a bit and is then re-heating but I am not 100% on this. There isnt any noise when hot water is drawing, thought in occasion there is a little bit after a shower, but he noise seems different, like a valve type noise - and it doesnt occur right away after the shower - can be minutes or hours.

My cylinder was installed by BG as a replacement for an old Premier Santon than started leaking last Feb. Cold supplies to taps and shower are off mains, not balanced cold on cylinder with hot from cylinder. Taps are mixer type through the house. One shower is a mixer shower in ensuite. (I think there was a similar set up on the Santon but am not sure.)

Late summer we reconfigured the ensuite - replaced old Mira mixer shower (was a plastic built into wall dial) with a new RAK Thermostatic Mixer. We also replaced the mixer tap (which has separate hot and cold handled) for a single monobloc, single handle mixer tap.

As the work was done we noticed that the mains pressure into the new shower was poor - and the sink/toilet refill wouldnt run at the same time. There were no other issues however and no noise from the cylinder was detected. As a result of work being done I changed the times that the HW was on from mostly during the night, to during the day (this was as the hot water was switched off for a day or so and I just decided to change it after that).

A local plumbing firm checked and there was a stone blocking the valve the stop under the sink. This greatly improved the mains pressure and shower was better, no issues with flush/sink etc. However a few weeks later we started hearing a banging noise when the cylinder was heating up. I couldnt figure out what was going on and neither could BG/Dyno. The noise was very loud. I am not sure if the noise was going on when the HW was running during the night, but I did used to waken up during the night so this may be the case.

This continued for some time until I discovered that the manual bypass was taking most of the water when the HW was on as it was just about fully open. I also discovered that cylinder was never getting up to its target temperature of 60, and when HW was used for showers the cylinder was becoming much colder than this. The banging continued however, usually in about 20-25% of the times the water was heating.

At the annual service for the cylinder I pointed out the issue to the local G3 plumber - the bypass was closed down significantly, and the recovery time of the cylinder improved dramatically, with it able to get to 60 again. The banging got better and less violent but still continued to some extent when heating. I called BG back - they said the bypass was too closed and opened it up a bit (this made the pump overrun at switch off a bit noisier and also got a noisy radiator but am ok with this) There also appears to be a strange noise like a flushing noise coming from the cylinder - usually after it clicks off at temp (or end of the run now) - but the tundish is totally dry and there does not appear to be any water being expelled outside anywhere.

This did not solve the problem, though it was no worse, the cylinder still makes noise when heating - again, it tends to be worse on the cycles after the water has been drawn down a bit.

I am speaking to the manufacturer regarding the noise and will call back BG as and when.

There is a 3bar PRV under the sink(newly fitted when the water pressure issue was resolved) this matches the configuration of the combination outlet on the cylinder. There have always been mixer showers and taps in the house (before and after BG fitted the new cylinder) although there were changed for newer fittings - there has been much debate here about balanced colds and that this is better, but the new cylinder was a retro fit and probably the same as the old Santon with no balanced colds being used.

Can anyone help? I cant work this out - could it be linked to the work we did? Is it down to the cylinder which have had reported issues on them.

I clearly cant add a balanced cold retrospectively (neither did BG obviously) and I cant rip out the ensuite and start again.

I am looking to try and move conversations forward with the suppliers or installers to see what can be done - clearly no one but a G3 will touch anything on the cylinder. I have learned what I can the last few months but am this is not my area at all. If anyone can help me that would be really appreciated as this is incredibly stressful for me, and indirectly, my family.

Thanks in advance.
 
Last edited:

John.g

Messages
2,832
Don't think you need to be G3 to do the following but will soon be told if you do.
You will need a 0 to 10bar pressure gauge and a few fittings or the PG may come with a fitting.
Balanced (un) cold pressure: I would either check this or get it checked, shut the cold supply to the cylinder, slowly unscrew the blank on the combination valve and ensure/check no pressure which there won't be if the downstream non return is tight. install the PG and restore the cold water, observe this pressure during normal HW usage and also with no HW usage after a hour or two and see if the pressure is rising from its nominal setting of 3 bar.
 

Poiuytr

Messages
24
Hi John, thanks for jumping onto this thread.

I'll most likely get BG/Dyno out to do this.

Can I ask. If my mains pressure is less than 3 bar what might that do? Is the mains cold pressure not what drives the delivery from the cylinder? I dont understand why there would be a huge differential causing a problem - please excuse my ignorance here.
 

John.g

Messages
2,832
Yes, it is the mains pressure but via a PRV (pressure reducing valve) that drives the HW out of the cylinder, if, for whatever reason, this pressure is say only 1bar and the cold water from the other PRV is 3bar, then the most likely result is that the thermostatic mixer valves will give a much reduced output as they are effectively mixing at the 1bar reduced pressure, it shouldn't normally cause noisy cylinder operation though, but I think everything should be looked at, this is a very easy check to carry out and I'm surprised that it wasn't looked at previously even if only to confirm that all is well, of course you could say that the cold water PRV outlet pressure should be checked as well, they have to start somewhere or just replace your cylinder.
 

Poiuytr

Messages
24
Thanks John... so with the 'double PRVs' theoretically the mains cold and cylinder HW driven by the mains should be 3 bar max on each. I am not overly fussed about whether the shower is super powerful, I am more concerned about getting the banging to stop... the previous shower (which was probably affected by the blockage just above the stop) wasnt great, not was our electric shower prior to clearing the blockage.

If the pressures are equal then I dont see how the new shower or tap could cause any issues (backflow?) back to the cylinder. We did put in a new kitchen mixer tap earlier a couple of months prior (a Bristain Easy Fit) but cant see how that might be linked.

So best course is to have BG/Dyno check the pressure at the cold mains, the HW cylinder and the EV then. If I could at least discount that any of our changes might have cause this it would be a relief.

Meantime I am waiting to hear back from Gledhill after sending them some audio files.. will give it a few days and then chase and / or contact Dyno.

The cylinder is about to start its PM cycle after a bit of a run down so will monitor.

Thanks again
 

John.g

Messages
2,832
As long as both pressures are reasonably equal say 2.5 to 3.0 bar then no problems and should result in good flowrates .
Might be worth heating the cylinder with electric iimmersion for reasons I gave in other thread re coil flexing etc.
 

Poiuytr

Messages
24
Very quiet cycle just there, quietest one noted in a number of days, was also pretty quiet this morning - as noted this one after a bit ot HW drawdown from shower. - not much other HW used from any other taps today. Got itself back up to its tgt temp of around 60 in about 17 mins. Some minor ticks and clicks but that was all. More observation required.. cant work out any pattern, rhyme or reason to this...

I know on a couple of other threads that the manufacturer said that noise was normal expansion and contraction noise - not convinced, but if this is one of the cylinders with the wrong curing and drying time then maybe one without these issues would be quieter.

Of course it will probably bang away tomorrow now.
 

Poiuytr

Messages
24
...and as expected it did have a bang away to itself yesterday - again, yesterday there was more draw down on the hot for showers - but unlike the previous day where there was no noise showers were taken some time after the morning run heating cycle was over - a gap of lets say 7 hours or so. A few mins after the shower was done the cylinder made a single bang. Then on the next heating cycle which was made around an hour after the shower was taken and with the cylinder refilled with cold (but not all the way) it also banged - same noise.

This to me suggests that there may be contraction and expansion issues within the cylinder - as previously noted things do appear worse when more hot has been drawn from the cylinder. There is no immediate noise when hot is being drawn from showers / taps or judder or anything else - the shower runs fine and provides a decent mix of hot and cold so cant see it being the direct culprit here - just indirect as its only really showers where we use a more significant amount of hot.

This morning, pretty quiet again, so this seems to be the problem - it doesnt like cooling and subsequently heating up again - if there is a problem with the insulation as has previously been noted with some of the Gledhill cylinders this would also seem to suggest that this is part of the problem here.

As before I have audio of the sounds and will pass on to Gledhill. Its a decision now as to what I do in terms of the speed of getting BG/Dyno back about this issue - whether I wait to hear back from Gledhill or not first - I'm not sure how long they might take to come back and not sure what their thoughts are.
 

Chuck

Esteemed
Messages
2,365
Its a decision now as to what I do in terms of the speed of getting BG/Dyno back about this issue - whether I wait to hear back from Gledhill or not first - I'm not sure how long they might take to come back and not sure what their thoughts are.
Keep in mind that unless you bought the cylinder from them direct, you have no contract with Gledhill and anything they decide to do will be discretionary on their part. On the other hand, if you paid BG to supply and install a cylinder and the result is of unsatisfactory quality then they have legally enforceable obligations to fix it or refund your costs.

So, my advice would be to get back to hounding BG without delay. Consult your solicitor or Citizens' Advice for the correct way to word the letters of complaint so it's clear to the recipient they're going to end up in the small claims court if they don't get it sorted.
 

Poiuytr

Messages
24
Keep in mind that unless you bought the cylinder from them direct, you have no contract with Gledhill and anything they decide to do will be discretionary on their part. On the other hand, if you paid BG to supply and install a cylinder and the result is of unsatisfactory quality then they have legally enforceable obligations to fix it or refund your costs.

So, my advice would be to get back to hounding BG without delay. Consult your solicitor or Citizens' Advice for the correct way to word the letters of complaint so it's clear to the recipient they're going to end up in the small claims court if they don't get it sorted.
Thanks Chuck.

The cylinder was supplied by BG under their Homecare cover after my old Santon one leaked last year so ultimately I always thought that BG / Dyno would be the people who would have to rectify. I have had them out so many times now and they are none the wiser - the people are nice enough but you never see the same person twice, but you cant help but feel that they don't really know their way round these systems which must surely now be fairly commonplace. The changes to the bypass I mentioned above did make a bit of a difference in terms of frequency I think, but it really seems to me like an issue of contraction/expansion at a level which does not seem correct to me - I suppose my point in engaging with Gledhill was to get their take on it especially as it appears there were others with similar issues in the past.

I remain baffled by it all, but I am clearly not qualified the world of plumbing or engineering and cant fathom why this would be happening, cant see how anything we could have done around the house would cause this either

JohnG has been of great assistance so far - when BG (most probably Dyno though) come out next time am more and more informed now thanks to the forum and opinions and thoughts given so thank you again for your reply. I've just sent another couple of audio files across to Gledhill so will give it a couple of hours then just in the off-chance they come back to me with some insight but agree that I need to get them back soon as they installed and supplied.
 

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