Advice - Gledhill Stainless Lite

[IDC]

Hi all,

Looking for some advice as a previous posting suggested there are some people quite experienced with Gledhill system on the forum.

I'm having an issue whereby when the hot water has been on and any hot water tap/shower outlet is opened, the hot water pressure is significantly higher than usual. It then returns to normal after a few seconds. If however, the tap/shower is turned on full to the hot, there is a loud vibration and pipe rattling in the area where the cylinder is housed.

(Please upload the video directly to the post rather than linking elsewhere - the content will one day be erased and we are left with a broken post link then)

Once the pressure has returned to normal through opening a hot water outlet, this issue will not occur again until the hot water has been on again. The cold water pressure is totally unaffected and does not cause the vibration/high pressure when in use on any occasion.

There is no water dripping through the Tundish.

The PRV and expansion vessel have both been replaced earlier in the year and have been verified by the engineer as being installed correctly and the PRV is the correct rating.

The Geldhill engineer who visited today recommended that we change our expansion vessel to a 25 litre capacity, from the current 18. Having looked at the manual, it appears that the recommended size expansion vessel for this system is 18 litres. At the time, the engineer inferred that the vessel fitted was the incorrect size, however, the manual seems to suggest this is not the case.

I've had a number of different people (G3 certified) look at this issue and no one can pinpoint the source of the problem (hence why turning to Gledhill directly).

A previous engineer suggested that it is common to have to put the expansion vessel on its side to prevent/limit virbations/noises, however, due to area where the cylinder is housed, this isn't an option unfortunately.

Another has suggested cold water backfilling the system could be the issue, however, I would assume this would mean this vibration/noise would happen far more frequently.

Keen to see if any has experienced similar issues and can shed some light on whether the suggestion of a larger vessel is really going to help?

Obvious caveat, I'm not working on any of this myself!

Thanks

 

[townfanjon]

Can you take a pic of the pipework and controls on the left hand side of the cylinder .

 

[IDC]

Can you take a pic of the pipework and controls on the left hand side of the cylinder .

Yeah sure - I'll pop one up.

After seeking a bit more clarification from the engineer, it would appear that the system is not using a balanced cold feed. (Not too sure why, as this system was installed prior to me owning the house) and the suggestion of using a larger expansion vessel is to take up the extra expansion in the system caused by the balanced cold feed.

If the feed isn't balanced, would it be possible that what I'm experiencing is excess pressure caused by the unbalanced cold backfilling into the system? Presuming so, would a larger expansion vessel aid/solve this?

 

[townfanjon]

An unbalanced feed can potentially cause problems , but theres a few things to check first , however asuming the Gledhill guy is “ switched on “ I am pretty sure he would have seen any faulty pipework .

 

[IDC]

An unbalanced feed can potentially cause problems , but theres a few things to check first , however asuming the Gledhill guy is “ switched on “ I am pretty sure he would have seen any faulty pipework .

Here's a few pics

Expansion vessel - The nut coming off the hot water out the tank is because at some point, someone had attached the expansion vessel there (God knows why)

Central heating filler loop coming off the mains.

Inlet group (PRV and NRV) with expansion vessel coming off.

According to the manual "The cold water supply to any mixer taps/showers must be taken from the cold water tapping of this valve to ensure balanced hot and cold pressures. This valve is factory set to ensure the correct operating pressure for the Stainless Lite".

I'm assuming this is where my problem is with regard to not having balanced cold?

Tundish and PRV coming off tank

 

[townfanjon]

blimey that lot isnf half sandwiched in there.
It doesnt help anybody trying to help , not your fault but can you take a pic slightly further back I / we need to see where the ex vessel is fed from , its hard to tell but does it go back to the tee under the inlet control set ( red valve )

 

[IDC]

blimey that lot isnf half sandwiched in there.
It doesnt help anybody trying to help , not your fault but can you take a pic slightly further back I / we need to see where the ex vessel is fed from , its hard to tell but does it go back to the tee under the inlet control set ( red valve )

Yeah, I don't think the previous owners/original installer thought about future maintenance!

The expansion vessel is indeed fed to the T under the inlet control valve. I've marked it below

I am under the impression that it would ideally be attached to the inlet control valve, but it doen't look like there's enough space without having a super-tight bend in the pipe.

 

[townfanjon]

Yes its correct, personally I like them in the correct port on the ICS , but teed in there is fine .
Excessive cylinder temps wont help , is the cylinder stat set at 55/60 degrees?
What is the ex vessel pressure, did the engineer actually check it ?
Have you any idea on the incoming mains pressure is ?

 

[IDC]

Yes its correct, personally I like them in the correct port on the ICS , but teed in there is fine .
Excessive cylinder temps wont help , is the cylinder stat set at 55/60 degrees?
What is the ex vessel pressure, did the engineer actually check it ?
Have you any idea on the incoming mains pressure is ?

Cylinder temp is set around 50 . Had previously tried dropping the temp right down over the course of a few days to see if it made a difference, but it did not.

Not too sure on the incoming pressure as no pressure gauge anywhere in the system.

I don't believe the engineer checked the pressure in the expansion vessel, but, it was a new vessel less than 2 months ago. I guess I can just get a schrader-based pressure guage and attached it to the port to verify?

 

[Brambles]

Possibly worth having having a pressure gauge fitted on your incoming mains and also on the tank inlet after the combination valve.

It may seem to be a bit of overkill, but it makes it so much easier to work out what is going on.

I assume that (in the absence of a balance cold) you have checked all/any mixer taps / valves for high pressure cold back feeding the system?

 

[IDC]

Possibly worth having having a pressure gauge fitted on your incoming mains and also on the tank inlet after the combination valve.

It may seem to be a bit of overkill, but it makes it so much easier to work out what is going on.

I assume that (in the absence of a balance cold) you have checked all/any mixer taps / valves for high pressure cold back feeding the system?

Ok sure, I'll look into getting that done. Hopefully space isnt at too much of a premium after the combination valve (as you can see from the above, it's pretty tight!)

What would be the best way to check for the cold feeding back? I assume turn off each tap/mixer over the course of a few days to try and see if turning one off stops the issue? If identified as the problem, is the fix to have a non-return valves fitted?