Heating Info From Warmair.net

Solar Heating

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During the fuel crunch of the 1970s, solar heating as well as alternative energy sources took center stage and became a priority for homesteaders (a by-product of the flower child and hippie days of the 1960s). Many new forms of glazing were developed as well as paints and metallic coatings to enhance the collection of solar radiation. With predictions of $2.50 per gallon home heating oil prices by the mid 1980s and forecasts of world reserves running out by the turn of the century, manufacturers formed new research departments and new companies to compete for the most efficient solar collectors. The federal government even offered tax incentives and credits to homeowners building new homes with solar heat. Solar heating was gaining momentum, but the forecasters failed, and Reaganomics threw conservation to the wind to boost the economy and solar energy was forgotten. Many of the developing solar companies turned their attention to other products or folded completely.

Aside from the cost savings, the use of solar energy has zero effect on the environment. If the negative effects of burning fuel become a factor, the use of solar energy becomes a benefit to the environment.

Solar heating systems fall into two categories: passive and active. Passive systems use the sun’s rays to heat a surface directly, storing the heat in a mass of concrete, rock, or water. At night the heated mass radiates the heat into the desired space. An active system collects the sun’s energy in a medium such as air or water and pumps it to a storage facility, then pumps the heated medium to the space as needed. The newest active systems use special solar cells to convert the sun’s rays to electricity and use it as it is generated or store it in batteries to be used as needed.

A passive system has no moving parts other than motorized shades or insulation barriers to prevent heat loss at night through the glazing. The most common passive system consists of a large room that resembles half of a green house with a wall of glass or other transparency facing due south or north (dependent on the building location in respect to the equator) to prevent infiltration of outside air. The solar radiation becomes heat energy as it passes through the glazing and strikes the storage medium. A wall of concrete, a floor of concrete or stone, or large vertical cylinders filled with water are used to store the heat. At night, as the temperature of the home drops, doors between the storage room and the house are opened so the warmth that has been stored will radiate into the air and temper the home. Insulated shades or blankets covering the glazing during the night will keep external heat loss to a minimum.

Active systems are more complex. The solar radiation that passes through the glazing falls on a collector plate. The plate can be a duct with air flowing through or a plate with loops of piping carrying water or refrigerant that is warmed and pumped to the space to be heated or to a storage facility. If air is used as the medium, a large bin of rocks or a layer of rocks beneath the floor of the house will absorb the heat to be stored. If water is the medium, it will be pumped to a tank, and can be circulated to a conventional radiator system when heat is needed. If a refrigerant is collecting the heat, it will follow the same design as a heat pump system. Water will be heated in an exchanger and stored for later use. The refrigerant system eliminates the need for anti-freeze protection and drain down that a water system requires.

With additional piping and a heat exchanger, all solar heating systems can produce domestic hot water. The earliest solar systems were for domestic hot water supply, then expanded to meet the heating demands of the home or to heat swimming pools.

As a free source of energy, many unique methods of collecting and storing solar radiation have been installed in homes and office buildings over the years. There are so many, they cannot easily be categorized. Many books have been written listing the thousands of applications, each one exclusive to the needs of the structure.

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