Solar heating systems
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Solar hot water systems use sunlight to heat water. These systems may be used to heat domestic hot water or for space heating. These systems are basically composed of solar thermal collectors and a storage tank. The three basic classifications of solar water heaters are:
- Active systems which use pumps to circulate water or a heat transfer fluid.
- Passive systems which circulate water or a heat transfer fluid by natural circulation. These are also called thermosiphon systems.
- Batch systems using a tank directly heated by sunlight.
A Trombe wall is a passive solar heating and ventilation system consisting of an air channel sandwiched between a window and a sun-facing wall. Sunlight heats the air space during the day causing natural circulation through vents at the top and bottom of the wall and storing heat in the thermal mass. During the evening the trombe wall radiates stored heat
A transpired collector is an active solar heating and ventilation system consisting of a perforated sun-facing wall which acts as a solar thermal collector. The collector pre-heats air as it is drawn into the building's ventilation system through the perforations. These systems are inexpensive and commercial models have achieved efficiencies above 70 percent. Most systems pay for themsleves within 4-8 years.
