New Gledhill Stainless Lite Indirect Unvented alarming popping noises.

[samba1]

Happy Christmas everyone,

We’ve just had a new Gledhill Stainless Lite indirect unvented cylinder installed by Dyno. It is making an alarmingly loud popping noises when the hot water is being used, not always but very very often.

Mentally to me, it seems like the inner casing of the cylinder is flexing in and out (just like a plastic water bottle under a pressure change).

I have read that these are thin cylinders (hence the lite) and many have reported issues, even after a replacement.

Those of you experts out there who are familiar with this cylinder and it’s issues, is my best course of action to get Dyno to replace with another brand/model, rather than go with a replacement of the same brand/model?

Dyno have requested Gledhill to come on site, but I have read some posts saying the problem reappears after replacement. The visit will now take place in the new year, but I want to be prepared and not be fobbed off.

In your experience and expert opinion what is my best path here guys? Is it worth just insisting Dyno to get a refund and go for another brand/model (I’m assuming that is an option)? If so which one?

Thanks!

P.S. Dyno guys have checked the pressures, i.e. reduced the mains down to 3bar, and on Gledhill’s telephone advice reduced EV from 3bar to 2.8bar.

 

[John.g]

In series or parallel?, don't think PRVs are designed to operate in series?.

 

[John.g]

You’ve got it spot on, there is no balance cold supply from the valve block it is blanked, as the cold supply pipework to showers is not exposed in any way from the airing cupboard and so remains fed directly from the mains (which has the 3bar PRV and gauge). I’ve attached a video perhaps that might make it easier to see setup.

I will ask if Dyno will put a PG on the cylinder, good suggestion!
View attachment 67544

Can you clarify for me your understanding of these water supplies.

Is it mains, then PRV (reduced to 3bar) then this supply to mixer taps/shower.
AND Mains to cylinder block PRV then this supply (3bar) to HW cylinder.
or is it
Is it mains, then PRV (reduced to 3bar) then this supply to mixer taps/shower.
AND outlet (3bar) from the above also supply to HW cylinder but through the cylinder block PRV.

Where is the cylinder cold water supply NRV installed?

 

[samba1]

Can you clarify for me your understanding of these water supplies.

Is it mains, then PRV (reduced to 3bar) then this supply to mixer taps/shower.
AND Mains to cylinder block PRV then this supply (3bar) to HW cylinder.
or is it
Is it mains, then PRV (reduced to 3bar) then this supply to mixer taps/shower.
AND outlet (3bar) from the above also supply to HW cylinder but through the cylinder block PRV.

Where is the cylinder cold water supply NRV installed?

Yes, it’s the former set up.

I’ve tried to draw out the setup, hope that makes some sense. I believe the cylinder cold water supply NRV is within the combination valve, which precedes the EV and Cylinder.

EV was reduced to 2.8bar by Dyno on Gledhill’s telephone support, but still hear popping alarmingly when water is being drawn. I really suspect the cylinder is flexing in and out, just like a plastic water bottle when pressure changes. The stainless LITE cylinder is lightweight perhaps due to thin internal cylinder wall? This 210litre cylinder weighs 33kg, other 210litre ones I see weigh 45kg… just a thought…

 

[king of pipes]

Monitor the pressure gauge at the prv when a shower and cold tap are running and see what pressure you have ? You may have 3 bar standing pressure but not 3 bar at full flow ?

 

[John.g]

Agree, but IMO, more importantly, since the cylinder is fed from a different PRV, install a PG on the cylinder and monitor this as well.

 

[king of pipes]

Ideally yes but its a new install so the combination set up should be factory set ? you need to make sure your putting 3 bar water pressure and at a decent volume 20 + litres a minute into the cylinder, if you take more out than you put in it can cause the problem your experiencing.

 

[king of pipes]

Below are examples of how it should be installed

 

[John.g]

There no attachments KOP.....

 

[king of pipes]

Hot and cold supplies ideally how it should be installed 😉

 

[moonlight]

Video watched, one thing I can see wrong supply taken from cold water prv not from inlet combination valve.

 

[John.g]

The point was made that if both PRVs are supplying water at the same pressure then system should work OK, I would think that you could have at least 0.5bar difference in the two and still have proper mixing but I would agree though and can't really understand why it wasn't done the "proper" way, I Iinclude a schematic once again which is quite clear, the EV is also wrongly installed so all these might conspire to cause noise in a paper thin unvented cylinder.

 

[samba1]

The point was made that if both PRVs are supplying water at the same pressure then system should work OK, I would think that you could have at least 0.5bar difference in the two and still have proper mixing but I would agree though and can't really understand why it wasn't done the "proper" way, I Iinclude a schematic once again which is quite clear, the EV is also wrongly installed so all these might conspire to cause noise in a paper thin unvented cylinder.

View attachment 67600

Thanks John.G I did question Dyno if the EV should be installed in the way it was, they said no. However, I was merely asking about the way it was piped, I.e. the flow of cold water has to make a 90 turn to go into the cylinder. Is this what you are indicating by being wrongly installed, or is it that it should be connected directly to the combination valve? I’m not 100% sure what ought to be the correct way…

 

[John.g]

I wouldn't be overly worried about a 90deg turn but I would much prefer to see a balanced cold mixing with the hot, a balanced cold means coming off the same PRV as the cold supply to the cylinder, ie the combination valve block. or whatever its called.
"I did question Dyno if the EV should be installed in the way it was, they said no." why didn't they change it then?.

 

[samba1]

I wouldn't be overly worried about a 90deg turn but I would much prefer to see a balanced cold mixing with the hot, a balanced cold means coming off the same PRV as the cold supply to the cylinder, ie the combination valve block. or whatever its called.
"I did question Dyno if the EV should be installed in the way it was, they said no." why didn't they change it then?.

Sorry, my typing is terrible!!!

Should read:

"I did question Dyno if the EV should be installed in the way it was, is it wrong? they said no that’s not a problem”

 

[John.g]

Well, if glendhill's installation is like the one I've posted there is no way that they will provide a new cylinder. They must have sold hundreds of these Stainless Lite, they can't all be noisy?.
A quick look through the installation manual doesn't show the position of the EV but it certainly shows the cold feeds taken off the combination valve.

 

[ShaunCorbs]

The inlet assembly is correct and the system is balanced without repiping the whole house, move on Jon neither of these would cause the popping noise

 

[TGF5454]

Hi samba1,

Did you ever resolve your issue, I have exactly the same symptoms and what sounds like an identical install.

 

[John.g]

Hi samba1,

Did you ever resolve your issue, I have exactly the same symptoms and what sounds like an identical install.

Is the expansion vessel sitting above your HW cylinder and piped from the cylinder hot water outlet as well?.

 

[John.g]

Also, if the expansion vessel is piped from the combination inlet group, ensure that it is NOT piped from upstream of the non return valve as shown (in the official Glendhill guide) but is piped downstream of the NRV, there may be a tapping for this from the ERV.

 

[samba1]

Hi samba1,

Did you ever resolve your issue, I have exactly the same symptoms and what sounds like an identical install

Hi samba1,

Did you ever resolve your issue, I have exactly the same symptoms and what sounds like an identical install.

Hi, yes sadly it was a case of swapping the cylinder. Replaced with a Joule and no issues at all now. My Gledhill cylinder had a new serial number sticker over a previous one, to me that suggests it was either reworked in the factory or a returned unit.

The date code was for November and the two numbers were 3-4 weeks apart. The whole situation was suspicious to me. There may be a perfectly good explanation for it but I struggle to see any other.

Check if you have any deformation on the outer skin to indicate any impact to the unit in transit. The other area of suspicion is the combination valve. Could just be a faulty batch. Mine was supplied with the cylinder and was made by Reliance Water Controls. The new Joule cylinder came with Caleffi combination valve.

if you still have the option to swap out I would try to entertain that idea. I understand that it’s not always a pragmatic option.