Basics of Solar HeatingActive solar heating systems use solar energy to heat a fluid - liquid or air - then transfer the solar heat directly to the interior space or to storage. system for later use. If the solar system cannot provide adequate space heating, an auxiliary or backup system provides supplemental heating. Liquid systems are more often used when storage is included and are well suited to radiant heating systems, boilers with hot water radiators, and even absorption heat pumps and chillers. Liquid and air systems can complement forced air systems. ACTIVE LIQUID-BASED SOLAR HEATING The solar liquid collector is most suitable for central heating. These are the same as those used in domestic solar water heating systems. Flat plate collectors are the most common, but evacuated and concentrating tube collectors are also available. It uses a heat transfer or “working” fluid such as water, antifreeze, or any other type of liquid that absorbs solar heat. At the appropriate time, a controller operates a circulating pump to move fluid through the manifold. The liquid flows quickly, so its temperature only increases 9° to 22°F as it moves through the collector. Heating a smaller volume of liquid to a higher temperature increases heat loss from the sensor and decreases system efficiency. The liquid flows either to a storage tank or to a heat exchanger for immediate use. Other system components include piping, pumps, valves, an expansion tank, heat exchanger, storage tank, and controls. The flow rate depends on the heat transfer fluid. Learn more about types of liquid solar collectors, their sizing, maintenance and other issues. HEAT STORAGE IN LIQUID SYSTEMS Liquid systems store solar heat in reservoirs...... middle of paper ...... delivered to the living space. This is a very important concept to keep in mind when designing and operating small and large systems. This low-quality solar heat is indeed very usable, but it should be managed differently than the high-quality 150-170°F heat produced by a forced-air furnace. A strong blast of air at 180°F from a boiler will be hot for the occupant of a home, while a strong blast of air at 100°F from an efficient collector or store of rocks can give the impression of a draft to the occupant, even if it heats up. the house. Without annoying drafts, it should enter the living space slowly and continuously and from several points. The rule does not apply when the collector is small, in which case it would be impractical to create multiple outlets. We can re-examine the different types of unit heaters, this time based on their specific air handling requirements.