Zilmet expansion tank block?

[mdshaw]

Brand new 18l Zilmet expansion vessel (red) and the neck seems to be blocked by thick black rubber. Is that the bladder, tank is pressurised but can’t be pushed in with a finger.

I just want to check as by the time an engineer comes it’s going to be too late to replace?

Matt

 

[snowhead]

Yes that's the pressurised bladder, it should be visible.

Once connected the pressure of the water will push it back in the cylinder as required.