Loud noise from cylinder when hot water used

[phatboy]

Hi,

In the last couple of months when we use hot water from any tap in the house at a particular flow rate, the pressurised water cylinder (or close by pipes) makes a loud whining noise, until the flow is changes at the sink.

I had some issues with a faulty PRV around the same time as this issue developed. The plumber at the time replaced the hot PRV, the cold PRV and fitted a non-return valve to the hot output of the cylinder.

Any ideas? Unfortunately the 1 year labour warranty has now passed, and I will of course be using a different plumber to resolve the issues if it is related to previous work!

 

[phatboy]

Nobody has any ideas?!

The guy who designs the installs for the company who installed it (not himself a plumber) said it could be a pressure problem with the expansion vessel?

Thanks
Tim