Just found this site & hope someone can help!! My combination boiler (Vaillant turbomax) refuses to heat the hot water unless the tap is set to full! it's only just started doing this.now i guess it's whatever tells the boiler that there is demand for water but where(and what!)is that part/sensor.I've read the book but that hasn't helped me.i've read some pages on the 'net which talk about setting this sensor to manual over ride?? Any help/advice would be great.TIA,dave
