Unvented hot water system noise when hot water demand is made

[kirks06]

Hi all,

Ready for War and Peace ? Hope you are all sitting comfortably, so let me begin...p.s. I am not a plumber, I work in IT so sorry if incorrect or wrong terms used !

We have a unvented hot water system, installed in Jan 2014. FlowMaster cylinder; Zilmet 11H HY-PRO (18ltr / 3bar pre-charged) expansion vessel, pressure relief valves etc....installation of cylinder completed during a complete house renovation, i.e. entirely new hot water and heating system, pipework (all copper), boiler the lot..

The system has been working perfectly for 2.5 years, then approx 2 months ago we started experiencing problems which have resulted in fixes, which have resulted in more problems.......

Problem No.1- Dripping coming from the tundish.
Resolution - Plumber identified the problem as an issue with the expansion vessel. This was completely full of water. Expansion vessel replaced. Inlet valves not replaced. Dripping stopped.

Problem No.2 - A couple of days after expansion vessel replaced...when demanding hot water from all sources (shower mix taps, single hot water taps in bath/sinks/etc...) would result in what I can only describe as "whoopee" cushion style noise, combined with a vibration throughout the entire house.
Resolution - Same plumber as above identified the problem with the inlet valves. Replaced inlet valves. This "fix" has not resolved the issue and we now have a situation where, not every time, but in the majority of cases when hot water is demanded we end up with the "noise", vibration, and wide awake household when I get up early for a shower before work !

I have attached a couple of images. 1. The valves that have been replaced; 2. Pressure gauge.

The issue, would appear to my untrained (dangerous) non-plumber brain is "pressure"......I have stood in the garage, where cylinder, expansion vessel etc...are housed, and observed the issue in action. The black needle in the pressure gauge in the photo will be above 3bar (picture doesn't show this); demand hot water; noise/vibration comes direct from expansion vessel; pressure drops back to 1 to 1.5bar. Once the pressure builds back up above 3bar again, which is a fe and repeat the issue....

How does a 3bar pressure relief valve allow the pressure on the gauge to get above 3bar which is clearly causing a pressure equalisation issue with the 3bar pressure expansion vessel when there is a hot water demand.


HELP !!!!! As I am not prepared to spend any more cash on fixes that don't resolve the issue.

Thank you

 

[townfanjon]

Sorry sir , cash required and a decent G3 qualified guy .

 

[Dotty]

Expansion vessel pressure hasn't been correctly set. Call your g3 plumber back as soon as possible.

Please don't attempt to fix this yourself. Unvented cylinders store a colossal amount of stored energy and have the potential to take the side of your house off if mistreated.

 

[kirks06]

Don't worry, I am not planning to fix anything myself ! I am the Frank Spencer of the plumbing world.

The expansion vessel pressure is at 3bar the plumber showed me last time he came, he plugged a gauge into the top of the vessel and the reading was 3bar ????

What is a "G3 Plumber" and how do I find a good/recommended one in my area ????

 

[townfanjon]

Frank , G3 is the qualification to work on unvented cylinders . Theres a section on here " i am looking for " etc etc sorry I cant do the link , but somebody soon will no doubt

 

[unguided1]

In my opinion the noises Yer describing could be a faulty expansion vessel was fitted!

 

[rpm]

[DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas Engineer[/DLMURL]

 

[Chalked]

Faulty expansion vessel, or wrong one, or incorrectly set!

 

[Rachiex]

I'm no help here whatsoever, not a plumber, but intrigued by your issue as I am being woken by vibration in early hours, it seems by neighbour in downstairs or adjoining flat...

 

[unguided1]

I'm no help here whatsoever, not a plumber, but intrigued by your issue as I am being woken by vibration in early hours, it seems by neighbour in downstairs or adjoining flat...

May not be the same issue, Yer neighbours could be just a water hammer on a valve or loose pipe work.

 

[Radioman]

Can you get the original installers back? Did the system get serviced annually?

 

[gassafe]

Pretty common problem on unvented hot water cylinder, normally in the morning when the tank is fully heated (highest peak pressure) and a tap or shower is open & the diaphragm in the vessel releases pressure / equalises causing that noise... should be a simple fix for G3 plumber