remove grey panel and u should c a black lever with a red microswitch to the left. when hot water tap is opened lever should move anticlockwise and activate m/switch. if it doesn`t then suspect dhw diaphragm in water section (2 types fitted)both with `ears` but one has hole in the middle.
dpmartin17@aol.com
paul martin
October 2007
I can answer this question...
Why no hot water from my Vaillant VCW GB242 E? Heating O.K?