Expansion vessel question- max pressure

[SYS49152]

My current vessel has a max operating pressure of 3 bar. It needs replacing and I bought one with a max pressure of 6 bar. Can it be used in place or does it need to be like for like? Both are 18L

 

[Johntheo5]

6 bar is fine, surprised the other is only rated to 3 bar.

 

[SYS49152]

Thanks for the reply. I wasn't sure if 6 bar max pressure meant the vessel would be more difficult to fill compared to 3 bar. Maybe I'm misunderstanding the concept.

 

[Johntheo5]

Check the precharge (airend) pressure before installing, assuming this is for your heating system suggest reducing to 1.0bar and then fill it to 1.5bar (from filling loop) when refilling system.

 

[DP]

Check the precharge (airend) pressure before installing, assuming this is for your heating system suggest reducing to 1.0bar and then fill it to 1.5bar (from filling loop) when refilling system.

I suspect vessel is for a cylinder

 

[Johntheo5]

Possibly, although surprising that a 3bar EV would be used since a lot of unventd cylinders have the expansion PRV set to 6 bar and the cylinder PRV set to 7 bar, anyway, if it is, its recommended to set the charging pressure to 0.2bar lower than the cold water pressure reducing valve setting, apparently this helps to prevent water hammer.

 

[ianmcd]

I suspect vessel is for a cylinder

Why is it Red then mate ?

 

[DP]

My mistake. Did not look at that picture. Was assuming 18l would be for the UV cylinder.

 

[SYS49152]

Yeah it's for my sealed heating system. So just to clarify, it's ok to use the 6 bar vessel here in place of the 3 bar one?

 

[Johntheo5]

Yes.

 

[ianmcd]

Yeah it's for my sealed heating system. So just to clarify, it's ok to use the 6 bar vessel here in place of the 3 bar one?

you are getting mixed up with operating pressure and Max operating pressure, all system vessels are red if it is white it is for a potable water system (unvented HW Cylinder) your heating system vessel should be around the 1.0 Bar charge too high and it wont work , what you require will be stated in the boilers installation instructions