The data above shows the “vital signs” of the system. When the collector temperature exceeds the tank temperature by 7 degrees, pump#1 activates, storing hot water in the tank. This system works so well that we have many of our collectors turned upside down; reflecting the sun to prevent overheating! The energy capacity of the tank is a good indicator of how much electricity or natural gas has been saved by using the sun to heat water. The pictures below show the system tank, control system and collectors.