Boiler Water pressure too high!

[tabasco]

I have a 2 year old Worcester greenstar 35cdi boiler. At the weekend I noticed that the water pressure was down so I turned the tap at the bottom of the boiler to add more water and get it up to the high end of the green zone.

however, turns out the drop in water pressure was something unrelated to my boiler (a problem with the building or street or something) and the water pressure went back up of it's own accord. But becuase I've intervened, it's now too high, about 3 1/2 and making noises.

I know how to get the pressure UP on this boiler, but how do i DROP it? I'm sure it's very simple - but haven't a clue!

Advice gratefully received.

 

[MANDATE]

Bleed a radiator.
If the system is sealed from the street mains, then a drop in pressure cannot be related to anything other than your system.
It means you had or have a leak. If the pressure has increased enough it will open the 'pressure relief valve' and the pressure will drop and the valve will close again, but they don't always close fully.
Pressure should be about 1bar when heating cold, rising to 2bar when hot.
If you get a large rise. it would suggest the expansion vessel is not functioning correctly. It may have lost some of it's pressure on the 'air' side

 

[jon26]

You could always release some pressure through the safety discharge... but I wouldn't do it to often