hi i have been called out to a worcester 240 rsf which is not giving off hot water. the heating works fine and the water that does come from the tap is look warm. my first thought was that the diverter valve is at fault but the boiler fires up and the burner runs would this happen if the valve was only open slightly and this is where the warm water comes from. i think im right with my think and just need to know if this is right or not many thanks