Solar Expansion Tanks

The solar heat transfer fluid used by the Bosch Solar Thermal System expands when it is heated by the sun in the collectors. In order to compensate the volume change of the fluid in the system, a membrane expansion tank needs to be installed. The size of the expansion tank depends on the system pressure, collector area, system volume and static height of the system.

The expansion tank is a safety device to ensure that the maximum allowable operating pressure is never reached. The entire volume of the solar system is contained in the expansion tank. A properly designed system will compensate volume changes in the solar system and diminish the need to have a safety valve open.