| A thermosiphon solar collector system provides truly | | | | - There must be a minimum of hydraulic resistance |
| free energy. Unlike its active solar counterpart, passive | | | | and heat traps. |
| solar energy uses neither pumps nor external input | | | | Once these criteria are met, the system can function |
| power. Passive solar collectors need nothing but | | | | properly. Initially, as solar heat is introduced to the |
| energy absorbed from the sun to heat the water as | | | | system, the water in the collector tubes becomes less |
| well as to move that heat through the system. Once | | | | dense, resulting in convection flow upwards toward the |
| installed, a thermosiphon system will provide perpetually | | | | outlet of the collector. The heated water rises naturally |
| free hot water. During sunny periods the water in your | | | | to the storage tank or heat exchanger. This heated |
| collector is heated and pumped via the forces of | | | | water enters the top of the tank and the cooler water |
| convection to your storage tank, heat exchanger or | | | | at the bottom of the tank, being more dense, |
| indirect water heater, free of charge. | | | | descends down the return pipe to the bottom of the |
| The laws of thermodynamics dictate that certain | | | | solar collector. Providing there is a minimum of hydraulic |
| conditions exist to allow heat to flow properly | | | | resistance, such as sharp bends in the tubing; and the |
| throughout the system. If these mandatory conditions | | | | piping does not contain heat traps in the form of dips |
| exist, convection will naturally cause a thermosiphon to | | | | causing a negative pitch, then the heat will continue its |
| occur within the closed-loop system. These physical | | | | cycle unimpeded. |
| requirements are as follows: | | | | As more people seek alternative sources of energy to |
| - The output of the collector must be above the level | | | | reduce their heating bills or to be free of the grid |
| of the return. | | | | completely, renewable sources of power such as |
| - The hot water storage tank must be located above | | | | solar are sought more frequently. The thermosiphon |
| the collector. | | | | solar collector system satisfies this increasing demand |
| - The output of the collector must be piped to the top | | | | by offering a method of heating potable water or |
| of the storage tank or heat exchanger coil. | | | | providing a source of radiant heat that is completely |
| - The bottom of the tank or coil must return to the | | | | free to operate! |
| bottom of the collector. | | | | |