How do I lower pressure on a worcester 24i junior Boiler?

System pressure can be lowered by either opening the drain cock on the system or opening an air vent on a radiator and catching the water.
This should be done with the boiler off and when the heating has not been on (cold). The pressure should ideally be at 1.3Bar when the the system is cold. Does the pressure go up only when you use the heating? if so you have a problem with the boiler. You should then call in a Gas Safe registered Engineer to find the fault.
If the pressure goes up even when the heating is off and you have a filling loop with a braded hose, disconnect the branded hose to check the filling valve is not passing water. If it is passing then a new fill valve is required. If when this is disconeccted is pressure still goes up when the heating is not on the main heat exchanger may well be pin holed. Rare but I have had one or two.

Anygasman
December 2009