Thermosyphon Solar Water Heaters

Thermosyphon solar water heater systems use only the Sun to heat your water. These systems are truly passive solar water heating systems as they use natural convection to circulate water without pumps through your solar hot water heating system. These solar water heating systems can be very inexpensive since there are no pumps or wiring for the pumps.

In a simple solar thermosyphon system the holding tank or storage tank is usually mounted above the solar thermal collector. As water in the solar collector heats up it expands and becomes less dense. Since it is less dense it is also more buoyant than the cooler water behind it and so the warmer water "floats" up towards the storage tank.

As the warmer water is pushed upward, cooler water replaces it by gravity. Then as water cools in the tank it sinks back down to the solar collector and the process begins again. Water will continue to move through the system by this Convection.

There are two types of thermosyphon solar water heating systems:

Direct Thermosyphon solar water heating systems send heated water directly to the storage tank. This type of system is best for warm climates where freezing is not much of a problem.

direct solar thermosyphon

Indirect Thermosyphon solar water heating systems send heated water indirectly to the storage tank via a heat exchanger loop. The reason for this is that this type of system usually contains an antifreeze that cannot be mixed with the normal water system since antifreeze is toxic. This type of system is usually used in areas prone to freezing.

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