Open Loop System
a type of hot-water solar heating that uses a direct pumped system with one or more solar energy collectors installed on the roof and a storage tank below in a garage or utility room. A pump circulates the water from the tank back and forth to the collector. A differential controller senses the temperature variation between water leaving the solar collector and the coldest water in the storage tank. When the water in the solar collector is warmer than the water in the tank, the controller turns the pump on. The pump turns off when the water temperature drops to about 3â€“5 degrees.