Unvented Heating System - Noise Issue - Gledhill - 6 months on

[Johntheo5]

Could be but If problem persists with EV renewal would suggest sorting out the pressure drop after the combination set. After visit 1 when they recharged the EV and checked the pressure with HW on it was apparently 3.0 bar but you are now only seeing 2.0 bar or less since they installed another PRV to deal with the kitchen tap causing a perceived problem, I would reposition this PRV to serve the kitchen tap only and see if you now get 3.0 bar after the combination valve set. If you don't get 3.0 bar and the pressure is still say 2.0 bar then I would reduce the new EV precharge to 1.8 bar.
OR (if noise problem still there after EV renewal),
simply wind up the cold mains PRV fully and check for 3.0 bar after the combination set and if room allows install NRVs on both the hot and cold at the kitchen tap, the cold mains PRV can then be removed to avoid future confusion.

 

[jklondon]

Hi,

So we had the EV changed and all was good for a few months but now were back to hammer noise.

Attach picture and video, it only occurs when pressure builds up to over 3 bar. I have tried adjusting the mains pressure but it doesnt seem to help.

Any pointers welcomed again.

 

[Davey75]

Hi, I know the last post on this issue goes back to Nov 2023, but was a solution ever found regarding the fog horn noise and vibration banging? We have the same problem having had a Gledhill horizontal unvented cylinder installed in Dec 23, so been over 8 months now. We’ve had the multiblock changed 3 times now so it’s not that, and the heating engineer is baffled (British Gas trained and seasoned engineer). Noticed when he’s been out the noise goes away for about a week, but then returns with a vengeance. No works to bathroom / kitchen have been carried out following the cylinder installation so difficult to pin point what is causing the issue. Any help gratefully received?

 

[Madrab]

Hi, I know the last post on this issue goes back to Nov 2023, but was a solution ever found regarding the fog horn noise and vibration banging? We have the same problem having had a Gledhill horizontal unvented cylinder installed in Dec 23, so been over 8 months now.

As you suggest. it's an old post and it's always better to create a new post and link back to this if referral is needed as they can get quite long and a new post avoids having to trail through lost of old, non relative stuff

TBH though this subject has been discussed many times, with subsequent solutions, so a further searches may provide fruitful. This problem usually occurs when there's a mismatch in pressures between the EV and the mains supply when the cylinder is fully up to temp and it's the sudden release of that over pressure that creates the resonance @ the EV. It usually needs onsite tweaks and adjustments though, so can be really hard to remedy through a forum.