I have a Worcester Greenstar 24i junior boiler that is around 12 years old. I am having issues with the pressure on the central heating. When the boiler is off the pressure is dropping down to 0 (I know it should be around 1 bar). When on it is around 1 bar some of the time, but it can go up to two or even three at times. I also see some water at times from the pipe that goes outside (pressure release?)The heating is working OK its just that the pressure is all over the place. Anyone have any idea what the issue could be? Thanks