Expansion vessel pressure?

[Sly]

Hi all,

I have a 300l unvented cylinder heated by a Daikin air source heat pump. I'm getting a right grumbling noise shortly after running the hot water which I reckon is coming from the seperate expansion vessel. Any idea what the base pressure of this should be charged to please? It has 18 Litres capacity and states 2.5 bar on the label. Would raising or lowering this reduce the grumbly knocking monster in the airing cupboard noise?!There is also a pressure reducing valve fitted set to 2.1bar.

Cheers,

Sly

 

[Gordon T]

Do you have your unvented ticket?

 

[Phil B]

Assuming you are legally allowed to work on the system have you checked for a data plate giving you information of the vessels operating pressure? Always refer to manufactures instructions in the first instance.