Gledhill Unvented Cylinder Loud Bang Hot Water Demand

[Adam-Robinson]

Recently had a new heating and hot water system retrofitted in a domestic property. Previous hot water system was gravity fed with a vented cylinder. New system as shown in the photos. Installer commissioned system about 3 months ago and all was working fine.

There have since been two faults:

1.) About 6 weeks ago the pressure relief pipe came off inside boiler, large amount of water leaked from the boiler, cause was a faulty thermostat on the Gledhill cylinder. Damage caused to boiler as PCB was beyond repair.
2.) Within the past 4 weeks the Gledhill cylinder has developed a popping sound whenever there is demand for hot water. This has now got to a volume that is alarming if standing near the cylinder. I've attached a video of this happening.

Could an experienced and G3 registered plumber provide opinion on the overall installation as shown in the pictures - do we have a sound installation or are there signs of a sub-standard job? I would also appreciate any thoughts on what could be causing the loud popping sound coming from the cylinder.

Any comments gratefully received.

 

[Scott_D]

Is the noise when you draw off hot water or when it’s heated?

 

[Adam-Robinson]

Is the noise when you draw off hot water or when it’s heated?

Hot water draw off.

 

[Scott_D]

Have you asked the installer to check it over?
If the secondary hot return is a long run the expansion may be undersized

 

[Adam-Robinson]

Installer has been asked to check it over however has yet to come on-site, his current thinking is back pressure through a mixer tap which requires a pressure reducing valve fitted above the stock cock or a check valve on the offending hot pipe.

 

[Scott_D]

Could be a few different things.
Best to get the installer out. If they won’t/can’t find the cause you may have to pay another installer or call in the manufacturer

 

[samba1]

Installer has been asked to check it over however has yet to come on-site, his current thinking is back pressure through a mixer tap which requires a pressure reducing valve fitted above the stock cock or a check valve on the offending hot pipe.

I have the same issue on same cylinder (210litre version), what was your resolution?

 

[Adam-Robinson]

I have the same issue on same cylinder (210litre version), what was your resolution?

PRV fitted above main stopcock appears to have resolved the issue. Still slight pops when hot water is drawn off but nothing compared to the original post, certainly nothing that makes me jump when next to the cylinder! Installer has stated the popping noise is the movement of insulation due to expansion/contraction within the cylinder and nothing to worry about.

I'll be interested to hear about your resolution.

 

[EvilDrPorkChop]

Sounds like they're s*** cylinders, think i'll stay away from them Never been a fan of Gledhill

 

[John.g]

I have the same issue on same cylinder (210litre version), what was your resolution?

Did you ever get a pressure gauge installed at the cylinder?? Both the OP's installer and Shaun Corbs, in your thread, reckon its the insulation, if so, maybe no big deal apart from noise?.

What is the advantage of these "lite" cylinders, presume its to enable the installation of a bigger volume cylinder (+25 litres or so) and not require extra floor reinforcement?.

 

[samba1]

Did you ever get a pressure gauge installed at the cylinder?? Both the OP's installer and Shaun Corbs, in your thread, reckon its the insulation, if so, maybe no big deal apart from noise?.

What is the advantage of these "lite" cylinders, presume its to enable the installation of a bigger volume cylinder (+25 litres or so) and not require extra floor reinforcement?.

Hi, no still waiting for Dyno to return. I think my situation is different, the noise is really loud, it’s like someone taking a hammer and smacking the cylinder hard. It’s shockingly loud when water is drawn. I feel, it could be the cylinder flexing in and out like a plastic water bottle, and I suspect that the combination valve is faulty as it sounds like an aircraft when any hot water tap is turned on. It could be a sticking combination valve that is causing the loud bang, but because they’re so close to each other it’s difficult to gauge. I think I really have 2 issues, because the bangs are of different amplitudes, one is the combination valve and the other is the cylinder, both making shockingly loud noises. I could be wrong. The cylinder does have an 8 inch crease on the outside (which was present when supplied and dismissed as being cosmetic), and I see my cylinder serial number sticker has been placed over an older serial number (with a lower number), which says to me I have re worked (of even a returned) unit. All very suspicious?? The cylinder, EV and combination valve was supplied by Gledhill. Neighbour has exactly the same cylinder, EV and valve (also fitted by BG/Dyno). It’s silent, even when water is drawn, which is how my old cylinder and valves behaved before being replaced with a Gledhill lite. I think I have a lemon considering all the factors.

I really don’t know, but others have said they are lite, because they’re 10kg lighter than others so perhaps their internal cylinder wall are thinner, I see other manufacturers say their internal cylinder wall is 40% thicker steel, and their specs show an empty weight of around 45kg, whereas the Gledhill lite is about 33kg for a 210L.

 

[John.g]

Could be a sticking combination valve all right, the hot water flow might be a bit erratic if it is.
Has your neighbour got the balanced cold taken from the combination valve?, or did BG/Dyno install it like yours where the cold and hot are taken from two different PRVs, not that that shouldn't work OK, as probably dozens of cylinders plumbed in like that.

 

[samba1]

Could be a sticking combination valve all right, the hot water flow might be a bit erratic if it is.
Has your neighbour got the balanced cold taken from the combination valve?, or did BG/Dyno install it like yours where the cold and hot are taken from two different PRVs, not that that shouldn't work OK, as probably dozens of cylinders plumbed in like that.

Yep, plumbed exactly the same as mine, no balanced cold taken either. Both houses pretty much the same too with identical mixer showers. Only difference is that his pump is the previous model, mine is Grunfos UPS3, which was only replaced very recently.

 

[samba1]

Yep, plumbed exactly the same as mine, no balanced cold taken either. Both houses pretty much the same too with identical mixer showers. Only difference is that his pump is the previous model, mine is Grunfos UPS3, which was only replaced very recently.

Folks, I thought I’d try to close this problem off, the resolution in my case was a replacement cylinder (not Gledhill, but Joule), and no more banging. The expansion vessel was replaced with same make and model, and the combination valve was replaced with a Caleffi this time (not Reliance Water Controls), personally I feel there were 2 things at fault. The cylinder (which I suspect was a factory rework - as it had a new serial number stuck on top of the old one) and the combination valve being defective in some way.

Thanks to all that offered advice and guidance.

 

[Jurgen Klopp]

I have this issue with the 300 litre Gledhill Stainless Lite. After nearly 8 months of emails and calls to Gledhill I will be getting a new cylinder next week. The problem is that in order to produce more cylinders, Gledhill reduced the drying time for the foam from 21 minutes to 16 minutes and this is where the problems started. All cylinders made at that time have developed the banging noise, they have now gone back to a 21 miute drying time. They will try to resolve the issue by riveting the skins together but who wants rivets on a brand new cylinder ?1?!
If you have this problem tell them you want a new cylinder and demand the £120 call out charge be returned because it is not an installation issue, it is a Gledhill issue.