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In the 1970s, the Organization of Petroleum Exporting Countries (OPEC) refused to export oil to the United States and several other countries. The embargo touched off an energy crisis reflected by oil shortages, long lines at gasoline stations, higher prices and a global economic recession that lasted for several years. To relieve the pressure of higher heating costs on the household budget, people began to experiment with solar power to cut costs.
As a result of today's higher fuel prices, supply disruptions and increased global competition for dwindling fuel oil supplies, the cost of heating your home has risen -- sometimes dramatically -- over the past few winters. Now that Congress is considering imposing an energy tax through cap-and-trade CO2 emission restrictions, you might be looking for alternative methods to heat your home.
Building a new, passive solar house or investing in an extensive solar retrofit of your existing home might not be within the capacity of your budget. But there is a relatively simple and inexpensive solar add-on that lets you make use of free solar thermal energy to supplement your existing heating system and reduce your energy use. This magic bullet is a solar air heater.
Solar Air Heaters 101
Is a solar air heater a good solution for your home? Let's talk first about what it is and what it isn't. A solar air heater is an active system as opposed to a passive system. Passive solar systems rely on heat absorbing structural materials and building orientation that takes advantage of southern exposure. Active solar systems use solar panels to collect solar energy and fans to move the energy to a different place.
A solar air heater is intended to supplement your existing heating system, not replace it. The most efficient way to utilize a solar air heater is to install it where it can blow or diffuse warm air directly into a room that sees a lot of daytime use. Drawing on the principle that warm air rises and cool air sinks, the solar air heater pulls cooled air from the bottom of a room, circulates it through the solar collector where it picks up heat, then blows the warmed air back into the room.
Solar air heaters use roof, wall or window mounted solar collectors to heat the air that passes through them. The solar collector must be mounted on a south-facing roof or wall where it gets full sun exposure that isn't obstructed by trees, tall buildings or other shade producers. Smaller window units can be mounted under a sunny south-facing window. This type of solar air heater extends through the window, so you won't need to install any ducts or vents to enable air flow. These simple, direct-transfer systems don't store heat, so they won't work at night or on cloudy days.
Some larger systems use heat sinks, which consist of materials that can absorb and hold heat for a short time. During the day, excess heat is transferred to the heat sink for storage; when the sun goes down, heated air is transferred from storage to your house. Although a heat sink might extend your use of solar thermal energy into the night,
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