BackStop Solar Expansion Tanks are an integral safety device for every solar heating project. They feature a specialized EPDM Diaphragm that captures the expansion and condensation of the solar heat transfer fluid during changing climatic conditions, also known as 'stagnation'. Each tank withstands high temperatures while ensuring that the maximum operating pressure is never reached, safely extending the life of all major system components. The expanded volume of the solar heating system is contained in the BackStop Solar Expansion Tank. The size of the expansion tank depends on the system pressure, collector area, system volume and static height of the system.