Expansion tank on domestic water pressurised system

[ruffmut]

I have a pressurised water system in my house (domestic water supply). We are running the system at 3 bar. What pressure should the expansion tank be set too.

 

[DavyJones]

I have a pressurised water system in my house (domestic water supply). We are running the system at 3 bar. What pressure should the expansion tank be set too.

Are you talking about the correct pressure in the expansion vessel?

Look at the expansion vessel and it should be written on it. normally they need to be set at 1.1 to 1.5 bar. However it is important to look at data label.

 

[ruffmut]

Thats right Davy Jones.

I looked at the label and it says that the pre charge pressure within the tank is set to 3.5 bar. I haven't checked the pressure myself though.

I am getting water hammer in my house. All the pipes secured firmly and not moving (no pipes in attic). It always happens when I turn on the hot water. I went into my hot press and it seams to be coming either from the pipe going into the expansion tank or the hot water pipe from the water cylinder.

I read somewhere that if the expansion tank is not at the correct pressure this could cause the water hammer.