Unvented hot water system noise when hot water demand is made

[Thomoli]

Hi

Had an Expansion Vessel replaced as it was faulty (dripping from overflow pipe). Changed by the plumber but have had this noise ever since. Plumber has been back since to replace the new EV just in case that was faulty and also replaced the PRV but the noise still continues. It's at it's loudest first thing in the morning when hot water is run for the first time, then nothing during the day and then maybe a lesser noise when a shower is run late at night.

System installed 8 years ago, worked perfectly fine until the EV replacement.

Sounds like a car/motorbike starting up - like a vroom noise. I have a video, but can't see how to upload it?

Any ideas??

Thanks

 

[Hot&Cold]

Can you try to pinpoint where the noise starts from,a listening stick or a stethoscope can be helpfull

 

[flameport]

Had an Expansion Vessel replaced

Did they check the charge pressure and adjust as required,
or did they just shove it on and hope it was correct?

 

[Gasplumber]

Is ev piped in copper or flexi.
Apparently few noise issues can happen if a flexi.
Although I’ve not experienced it myself.

Also if a mega flow make sure ev is tees off in core t place. View the diagram