In order to enhance thermal stratification in the storage tank, it was assumed that the water of each loop is able to enter the store in two different heights, instead of having just one fixed inlet position for each loop. Thus one valve each is needed for the collector loop and the space heating loop. It was found that the impact of these valves on the fractional energy savings f_sav,ext of the investigated systems is relatively small. Depending on the reference conditions, f_sav,ext could be increased by up to 0.8 %-points.