Direct thermosiphon solar water heating system,
JWH Ferguson, Wikimedia CommonsA thermosiphon solar water heater system is considered passive, given its absence of any mechanical means to circulate water. Acting on the principle of warm air rising and cold air falling, the thermosiphon system relies on a solar collector, typically installed on the roof of a house, to convert the sun´s rays to heat energy.
A thermosiphon system works through natural convection. The cold liquid is heated through the solar collector at the bottom of the system. The warm liquid then rises upwards to the hot water storage tank situated above the collector. There the heat energy is either transferred indirectly to the water through a heat exchanger (indirect system) or the warm liquid itself is used directly.
The thermosiphon principle is applicable for all solar water heating systems. Such a device can be closed-loop or open-loop, and direct or indirect. With no mechanical or moving parts, a thermosiphon solar water heater system is relatively simple to design, install, and maintain. In addition, a thermosiphon system can be less expensive compared to other solar water heater systems.
Advantages & Disadvantages of A Thermosiphon Solar Water Heater
Despite certain advantages associated with a thermosiphon solar water heater system, one should take into consideration some drawbacks as well. Given the weight of a full water tank, a certain amount of structural reinforcement to the roof may be required. Consideration should also be given with regards to climate. If a thermosiphon system is to be installed in a frost prone area, the use of a special antifreeze liquid inside a closed-circuit system may be necessary in order to prevent the water from freezing.
Despite any potential drawbacks, the affordability and low maintenance of a thermosiphon solar water heater system makes it a great choice for any homeowner looking to take advantage of an alternative energy source with a minimal investment.