Gledhill Unvented Cylinder Loud Bang Hot Water Demand

Old UKPF 120379 · Jun 17, 2021

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.

Poiuytr · Mar 17, 2022

I suspect the issue has been longer running to be honest - maybe since install last Feb - I used to have the HW on during the night (with a short top up during the day) but changed the timings a while ago and this is when I first started hearing the noise - though I would say that used to wake up during the night so everything could be linked back to install date. BGs cover suggests that they replace if they cant fix it and there is clearly an issue here, not just for me, but others with Gledhill cylinders - having it replaced by BG (for another brand) would be my preferred solution - my previous Santon Premier ran until it eventually started leaking after many years of just sitting in the airing cupboard minding its own business. If they have fixed their drying times then it may be that a Gledhill replacement will work as and when down the line. I'd rather not pay for a replacement myself and dont think I should either.

Poiuytr · Mar 17, 2022

Watched back OPs video from June... noise is similar here - and also ties back to noise that is sometimes made at some point after shower usage here. I'm not quite sure I buy the line that this is just movement through contracting etc - am sure that cylinder make some kind of noise, but surely not that?

GLEDHILLSUCKS · Jun 30, 2022

Hi All.

Just came across this thread.

Firstly thanks for the info, it's been useful and has confirmed there is an issue with this cylinder. I am sure I read it last year, but since then, things have gone south again 🙁

Had a full system replacement, from gravity fed to unvented, new boiler etc March 2021.

Problems started almost immediately where my bathroom installer noticed the tank was leaking.

I called out the plumber who installed the system and the tank was replaced free of charge August 2021.

Since then, I have had no leaks, however I have been experiencing a loud bang from the cylinder. I've noticed this happens whenever the tank is heating up. If hot water is off, it seems to be fine. This bang has got worse over the last couple of months and is worrying to say the least as it can be heard throughout the house.

I am now experiencing a loud juddering sound when drawing hot water from the cylinder. This only happens after the tank has been heated, not after initial draw off or of the water is not being heated.

Poiuytr · Jun 30, 2022

GLEDHILLSUCKS said:
Hi All.

Just came across this thread.

Firstly thanks for the info, it's been useful and has confirmed there is an issue with this cylinder. I am sure I read it last year, but since then, things have gone south again 🙁

Had a full system replacement, from gravity fed to unvented, new boiler etc March 2021.

Problems started almost immediately where my bathroom installer noticed the tank was leaking.

I called out the plumber who installed the system and the tank was replaced free of charge August 2021.

Since then, I have had no leaks, however I have been experiencing a loud bang from the cylinder. I've noticed this happens whenever the tank is heating up. If hot water is off, it seems to be fine. This bang has got worse over the last couple of months and is worrying to say the least as it can be heard throughout the house.

I am now experiencing a loud juddering sound when drawing hot water from the cylinder. This only happens after the tank has been heated, not after initial draw off or of the water is not being heated.

Hi there. I too had an issue with the banging. As noted there seems to have been an issue regarding a batch of these cylinders. Times of manufacture differ and my understanding is that new cylinders are not affected but I dont know this - but the install date is not what matters here as there will be cylinder lying around storage at merchants etc.

In my instance, after much investigation by myself, BG/Dyno and rmuch eference to this excellent board I approached Gledhill directly on the issue. They inspected and advised that the repair was to rivet the outer skin - the rivet is at the back of the cyilinder so this will not affect any asthetics. I have heard some reports that this does not work, but so far, (very much) fingers crossed, two months after the repair, the banging has gone. Should it come back I would simply contact Gledhill again. The issue was noise of the casing during expansion and contraction. I would advise that, in consultation perhaps with your installer, that you speak to Gledhill on this matter.

I fully understand your concerns here, it is a very loud noise but hope that my reply will assist you in some way.

All the best.