I need to refill my Vailllant TurboMAX VUW 242e,282e but when I turn the valve nothing happens. Am I missing something?

I noticed that the pressure drops to 0 when I run the hot water and climbs to about 0.5 bar when the wate is turned off.

Does this mean I need to call a plumber?

Martyn Hickinson, March 2008

normally two valves will have to be opened,either a screw diver type slot and a black knob underneath boiler this allows water to pass into ch side,or a silver braided hose known as a filling loop with isolation valves at each end these require opening

paul, March 2008