Combi losing water - pressure gauge high

[Swell1]

Hi, our Worcester combi boiler has an issue ( around 10 years old, sorry it doesn't state a model on the front).

It loses water.

Today I topped up the water to 1.5, turned on the heating for 1 hour, pressure gradually goes up to 3 (in the red) and it drips water out of the pipe outside (overflow?)

Is the above description enough to point to a particular faulty part?

I will get a plumber but just wanted to see if I could identify the issue at all based on the above.

Thanks

 

[Wayners]

Expansion chamber or in our case it was the expansion chamber valve.
Gas engineer changed the pressure release valve first then repressurized the expansion chamber, that didn't work so they changed the valve on the expansion chamber and that worked.

 

[terryplumb]

Expansion vessel issue, either needs to be recharged or replaced if required

 

[dilalio]

Clean out or replace PRV (they can often be made to reseat.

Pump up EV but ensure pipework is open to atmosphere as in boiler drained and drain point open.

Following that, schrader valve defective, replace schrader or bladder defective, replace EV.