The solar air collector is a remote cousin of the more ubiquitous heating water solar collector. The principle of operation is similar. Sun radiation is absorbed in a layer of absorptive material, the energy in the light wavelength is converted to heat and trapped inside the collector casing (thanks to the greenhouse effect). The heat however is transferred to air and not to a liquid (water or anti-freeze liquid).The solar hot air collector is mounted outside the building usually flat on the southern wall of the building. The hot air is blown directly into the space to be heated or used as a pre heated air to the main air heater. So, this is one more way to achieve solar space heating
Advantages and Disadvantages of Hot Air Collectors
Solar Hot Air Collectors and other solar air heating methods have advantages and disadvantages (no single solution is perfect I’m afraid)
They are effective not only around noon time but also earlier and later in the day
Air doesn’t freeze like water (at least not where people live)
Small leaks in the ducts might cause a graceful performance degradation but not a major fault situation
Counting the plus points, let’s discuss the one minus point. Air collector is not as efficient as a liquid collector, simply because air is not as efficient heat transfer medium as liquid
Installation Considerations
Air collectors are usually integrated into walls or into the roof (for a new building) or mounted on the wall as a retrofit. One air collector can provide heating to one standard size room and it is not a solution for the entire house. Usually a fan is used to circulate the hot air to the room
Solar Hot Air Collector Video
One example of a commercially available Solar Air Collector draws colder air from the room through the bottom of the collector and blow the hotter air to a duct at the top of the collector. Integrated solar electric panel provide electrical energy for a fan that circulates the air. It can be mounted on a South facing wall or on the roof.
