Why does pressure in worcester 240 keep falling?

When you add water to the system you must as a minimum bleed the radiators,until water comes out,start with the lowest and farthest away from the boiler,and keep an eye on the boiler pressure,it needs to be about 1.25 bar.Also your expansion vessel may need recharging(to 1 bar).Not really something you should try yourself ,try topping up and bleeding system for now and see how you get on

Graeme Smith
October 2007