Worcester 35CDI combination boiler high pressure

[Mike8648]

I have a Worcester 35CDI combination boiler and am experiencing problems with excessive pressure.
I was having problems with gauge dropping and after topping up noticed that pressure relief line outside was dripping. When I checked the boiler the gauge had gone over 2.0 bar and continued to rise daily and discharge continued to drip.
I am fearing the worst thinking it's either the expansion vessel or one of the heat exchangers, I am pretty certain top up valve is ok as it's not a filling loop on Worcester boilers but a T bar connector.
Can someone please advise me before I have to get An engineer out to look at the boiler
The boiler was installed in 2002 and has been excellent and serviced annually upto 2008, but not since

Thanks

mike8648

 

[GWP-Stansted]

The red expansion vessel has either discharged or ruptured, the testing of them requires the boiler to be isolated from the rest of the system via flow and return isolator valves, and the boiler side pipe work to be discharged of pressure, there will be a schrader (car tyre type) valve on the expansion bottle, usual charge rate is between 0.6-1.0 bar pressure, the manufacturers instructions will detail this.