water pressure

[wilko1]

I have a Vaillant eco tech 825. When the boiler is not on the water pressure is a steady 1.0/1.1 bar. However when the boiler is heating the pressure goes quickly up to about 2.5 bar, if it is on for any length of time it can get up to 3.0 bar.

I've tried to check the expansion vessel by pressing in the little valve but neither water or air comes out.

Any help or advice will be appreciated.

Thanks

 

[jackthom]

If no water is coming out that's good but there should be some air in there which gets compressed a little when the boiler temperature rises, preventing the system pressure from rising excessively.

Take a look at the FAQ on 'Repressurising the Pressure Vessel'.

//www.diynot.com/forums/plumbing/faqs.37170/

 

[wilko1]

It's a Vaillant eco tech plus 824 that I have, not 825. Could anyone describe where the boiler drain off valve is, and also what is the best way of putting an inhibiter in.

Thanks