Spontaneous downward heat transport comparison tests of an improved system

A previous spontaneous downward heat transport solar hot water system has been improved by the adoption of a double control float valve. This component, derived from an industrial product, enhances the performances of this system. Comparison tests have been made between two hot water solar systems, one conventional with a differential thermostat and circulation pump, and the other one fitted with a spontaneous downward heat transport system. The parameters varied during the tests were the setting of the differential thermostat, the amount of daily water draw-off, and the threshold temperature of the water extracted. In most working conditions the spontaneous system had a higher efficiency. Advantages of this system are the independence from electrical energy availability, greater reliability, and the insensitivity to cold climates.