Expansion vessel issue possibly?

[Dragonfly]

Hi

I have a baxi duotec combi boiler that every day or other day needs topping up as pressure drops below 0.5bar.

When fired up it can reach OVER 2.5bar also whilst running CH.

Is this more than likely a flat Expansion Vessel that needs inflating or could there be other possible causes if this turns out to be holding 1bar once tested?

Would i need to drain the water from the boiler by using the Pressure release Valve or is there another area where water is drained from after closing both inflow and outflow valves and do i do all this woth the boiler completely switched off from the mains?

Thankyou

 

[cjg]

Expansion Vessel that needs inflating
drop the front panel on the rhs there is a drain tap white knob
put bucket under for all the water, top presure to 1bar .
leave open for 2mins see if its drops

 

[Dragonfly]

Expansion Vessel that needs inflating
drop the front panel on the rhs there is a drain tap white knob
put bucket under for all the water, top presure to 1bar .
leave open for 2mins see if its drops

Thanks for the info. Went over today and it seems to have held for the past week or so without over or under pressure so a bit strange but left it for now and if it occurs again I will do what you suggest. Thankyou