Humming from unvented cylinder

[Clint B]

Hopefully someone can point me in the right direction. Before I start I am G3 qualified. As per usual I was asked to rectify a leak on a combination valve. I installed a like for like 3.5 bar valve, all good, however I I checked pressure in exp vessel to find no pressure at all (Never been serviced!) and in addition a non potable vessel. Advised this must be changed and the location/orientation of it should be improved. This is to be done imminently, had to order one. I re charged the existing one to just over 3bar and since refilling, when a hot tap is opened there is a humming emanating from the cylinder cupboard, this probably lasts about 10 seconds and then fades. Can anyone give me some idea possible cause, ie is it a faulty valve or the vessel.

 

[king of pipes]

Think about it logically if it didn't happen before you changed the combination valve ?? then it must be a fault with the new one check your nrv , I fit flow through valves on the expansion vessels now as below I would definitely improve on the position and orientation of the vessel Kop

 

[Clint B]

Think about it logically if it didn't happen before you changed the combination valve ?? then it must be a fault with the new one check your nrv , I fit flow through valves on the expansion vessels now as below I would definitely improve on the position and orientation of the vessel Kop

Thanks KOP. I did suspect possibly combi valve, I despair at the standard of fittings nowadays, kept thinking it must be the valve and then thinking no it can't be its brand new. Ill have to lay out for another replacement.