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]

Can you turn off the coil heating or turn down the cylinder stat to shut the motorized valve and see if it still makes the same noises while using the hot water.

What are the cylinder and EV capacities?.

 

[samba1]

Can you turn off the coil heating or turn down the cylinder stat to shut the motorized valve and see if it still makes the same noises while using the hot water.

What are the cylinder and EV capacities?.

Hi, it still makes a popping noise when both valves are shut and hot water is used. Cylinder is 210l and EV is 19l (Zilmet)

 

[John.g]

Seems normal enough, the pressure will rise to 4.1bar when heating from cold but will fall to 3bar once 4 or 5 litres of HW is drawn off, so if the PRV is working properly then the cylinder pressure should stay very steady with a very small fall off if large volumes of HW are being drawn off which would suggest no real reason for flexing due to fluctuating cylinder pressures. Unlikely to be EV. Can you see any fluctuations in the pressure (if PG fitted)?.
Maybe suggest to G3/Dyno that the precharge pressure is reduced to 2 bar which would ensure that the diaphragm isn't bottoming out if cylinder pressure fell to 2.8 bar under heavy draw off, it would result in a cylinder pressure 4.5bar on initial heating but again will fall to 3bar once a few litres of HW drawn off.

 

[ShaunCorbs]

Sounds like the insulation maybe at fault

 

[king of pipes]

Any pictures of the cylinder and how it has been installed ?? I recently had to fit a pressure reducing valve on a unvented cylinder this should of been fitted as part of the packaged controls but wasn't for some reason ? pressure would build up within the cylinder over night then when hot water was drawn off in the morning the out going pressure was released and caused all sorts of pops and bangs , check your cylinder is well supported over it entire base , and the pipework is well supported also . Kop

 

[John.g]

Samba1 said that Dyno reduced the mains pressure down to 3bar so assumed that a PRV was installed, throttling useless as pressure will build up with no usage, unless PRV is drop tight then same result.

 

[samba1]

Any pictures of the cylinder and how it has been installed ?? I recently had to fit a pressure reducing valve on a unvented cylinder this should of been fitted as part of the packaged controls but wasn't for some reason ? pressure would build up within the cylinder over night then when hot water was drawn off in the morning the out going pressure was released and caused all sorts of pops and bangs , check your cylinder is well supported over it entire base , and the pipework is well supported also . Kop

Thanks @Kop, A reliance water controls combination valve has been fitted (it came with the cylinder along with a 19l zilmet EV), and the mains (as fault eliminating effort) has been fitted with a PRV, set to 3bar, and EV reduced to 2.8bar on Gledhill’s technical advice, but this morning as hot water was being drawn (and cold being fed into cylinder), I heard 2 or 3 loads pops within a space of ~45mins, if my assessment is not wrong, it’s usually within a few seconds of hot water being drawn.

I have posted pictures taken during install, as that shows pipe work.

The entire base is not actually supported, the old cylinder base was used. Not sure you can make out, but the cylinder has a crease about 8 to 10 inches long on the left hand side wall. This is how it was supplied. It did concern me a little but I suspected that it’s cosmetic, but if these cylinders have a thin internal wall, perhaps it has deformed and that is moving in and out as pressure changes?

 

[samba1]

Samba1 said that Dyno reduced the mains pressure down to 3bar so assumed that a PRV was installed, throttling useless as pressure will build up with no usage, unless PRV is drop tight then same result.

Hi @John.g, sorry for being a little thick here, I’m not quite following part of your post “throttling useless as pressure will build up with no usage, unless PRV is drop tight then same result.”, Am I correctly understanding it that reducing cold feed to house was not needed? Dyno did that as 1 shower started to run luke warm, and in the other shower it started to run stone cold, so it was done to balance the cold and hot to mixer showers, however it hasn’t helped though, they say nrv and/or thermostat in mixer showers now at fault (and they don’t cover that) but previous cylinder gave no issues with showers, (I now have a number of significant plumbing issues which all started as part of diagnosing air getting into rads issue, which still remains unresolved, and new additional issues manifesting). Not to confuse matters I posted the original issue with my rads building up with air as a separate thread, but oddly my cylinder was replaced by Dyno as part of a fault elimination step, and now rads still building up with air and new cylinder has presented alarming issues, and to top it off, since cylinder replaced the showers are running cold. I suspect the lack of flushing of cylinder installation may have caused debris to travel to mixer valves and causing the (Triton Combi HP) thermostatic mixer showers to become defective, only logical explanation I can come up with.

 

[John.g]

If dyno reduced mains feed pressure to house by just throttling the stopcock then yes that will cause problems when mixing hot and cold water as the throttled pressure will vary from full mains pressure to low pressure which is trying to mix with HW at a now fixed pressure of ~ 3bar, if all the cold water pressure is reduced (with a PRV) then it should work reasonably well but the normal way is as shown in the attached, don't know if yours is like this or not.
Also the EV is better off on the cold water side (as shown) as it act as a shock absorber.

Edit: This is a Glendhill schematic so might assume that dyno modified it like below??.

 

[samba1]

If dyno reduced mains feed pressure to house by just throttling the stopcock then yes that will cause problems when mixing hot and cold water as the throttled pressure will vary from full mains pressure to low pressure which is trying to mix with HW at a now fixed pressure of ~ 3bar, if all the cold water pressure is reduced (with a PRV) then it should work reasonably well but the normal way is as shown in the attached, don't know if yours is like this or not.
Also the EV is better off on the cold water side (as shown) as it act as a shock absorber.

Edit: This is a Glendhill schematic so might assume that dyno modified it like below??.

View attachment 67532

Dyno fitted a PRV under kitchen sink to reduce the cold mains to 3bar. The cylinder came with a combination valve, (also called mono block valve I think?) so it’s a NRV, PRV and ERV all in one, and the cold supply then splits to EV and cylinder.

I’ve attached a couple of pictures to try to show the actual configuration.

 

[John.g]

Regarding cylinder, do you have full mains pressure then the PRV, then the balanced cold water to mixer taps, shower etc, then the ERV, the EV should also be taken off here. What indication do you have of the pressure? is there a PG fitted somewhere?. What has the under sink PRV to got do with this, if anything?., is it just supplying mains cold water at reduced pressure (via a PRV) to single (non mixing) tap or taps?.

 

[samba1]

Regarding cylinder, do you have full mains pressure then the PRV, then the balanced cold water to mixer taps, shower etc, then the ERV, the EV should also be taken off here. What indication do you have of the pressure? is there a PG fitted somewhere?. What has the under sink PRV to got do with this, if anything?., is it just supplying mains cold water at reduced pressure (via a PRV) to single (non mixing) tap or taps?.

Yes that’s right. The under sink PRV with PG was Dyno’s effort to help balance the cold and hot supplies to thermostatic mixer showers, ie to get 3bar on both hot and cold. Hasn’t helped though, shower goes hot and cold as other taps around the house are used, I suspect debris from the cylinder install has made its way to them and the NRV and/or thermostatic valves are now playing up. The single non-mixer hot taps are absolutely fine, so I’m guessing the mixer shower valves (Triton Combi HP) are now need replacement? At £150 a piece for the thermostatic valve I’ve been asking in these forums whether it’s better to replace like for like valve (stock is still available) or get a newer mixer shower, but that means more plumbing work which I’m hesitant given the loud cylinder popping issues going on, (and Dyno indicated that they don’t cover showers, even though the shower saga started immediately after the cylinder was installed). One thing to note is that the old cylinder was 3.5bar version (Premier Tribune), whereas the Gledhill StainlessLite is 3bar supplying 2 en-suite and 1 bathroom.

 

[John.g]

How do you know what pressure the cylinder and balanced cold water are set to?

 

[samba1]

How do you know what pressure the cylinder and balanced cold water are set to?

To be honest I don’t. The gauge on the cold mains under sink says 3bar, and the combination valve supplied with the cylinder is fixed to 3bar in the airing cupboard, that said Dyno have not measured the pressure at the cylinder. Forgive my ignorance here, but the cold feed to showers are fed directly from the mains, as are all other cold taps. They’re not fed off the combination valve, as that was the original set up with the old cylinder. So if I have understood this correctly, I do not have a balanced cold feed to showers, but instead relying on the PRV under sink to offer 3bar to cold supply into thermostatic mixer showers.