Since 1992, SunEarth has teamed with Edward’s Solar Hot Water (now part of Rheem Australia), a world leader in the manufacture of stainless steel storage tanks and boilers, to market a packaged thermosiphon system under the brand name ‘SunSiphon’ in North America and the Pacific Basin. The SunEarth/Edward’s collaboration offers the best of two continents – the world’s finest thermosiphon storage tank and rugged, high performance SunEarth flat plate solar collectors. SunSiphon systems are available both with and without integrated heat exchangers for hard freeze and non-freeze climates, respectively. Thermosiphon systems have no moving parts and use no parasitic energy in their normal operation. The simplicity and long-term reliability of the SunSiphon thermosiphon system remains its principal selling feature.
If properly installed and maintained the SunSiphon glycol heat exchange system can safely be deployed in areas that experience annual hard freeze conditons. SRCC Rated Freeze Tolerance: 15° F for 18 hours.
A Thermosiphon unit is a completely passive design that relies on buoyancy effects to circulate fluid through the collectors as opposed to the pumps and controllers found in active systems.
When sunlight strikes the collectors in the SunSiphon system it heats the food-grade antifreeze within them, which then rises due to buoyancy into the jacket-style heat exchanger on the bottom of the storage tank. Here the antifreeze transfers heat into the tank, becomes cooler, and sinks to the bottom of the collectors to repeat the process.
During periods of no sun, the cool fluid in the base of the collectors is not heated, does not rise, and thereby stops circulation of the antifreeze. In this manner, thermosiphon units achieve the operational characteristics of active systems but without the pumps and controls