Air conditioners provide more than just the luxury of cool air on a hot day. They reduce the risk of heat-related problems such as heat stroke or heat exhaustion. Heat also causes strain on the heart and the immune system. In some climates, air conditioning is a real necessity, especially for the elderly or those with compromised immune systems. There are three basic types of air conditioning apparatus. Portable air conditioners cool a small space and can be moved from room to room using a simple window vent. Room air conditioners are installed in a window to cool a single room. Central air conditioning cools an entire structure, which can be anything from a small house to a gigantic mall or factory. Though the initial expense may be greater, central air conditioning is the most economical way to cool a home, especially if the system is divided into zones. Air conditioners work on the same basic principle as other types of refrigeration--by effecting a heat transfer. The most common type of air conditioner uses an electric motor to power a compressor. The compressor causes pressure changes between two compartments. A fluid refrigerant is pumped into an evaporator coil, where the lowered pressure causes the refrigerant to evaporate. In the condenser, the evaporated refrigerant is compressed and condensed once again into a liquid. Air conditioners also remove moisture from the air, and the lowered humidity helps reduce the perceived temperature. The Federal Trade Commission requires air conditioners to display black and yellow Energy Guide labels. These labels provide information regarding the unit's energy efficiency. They also list projected annual operating costs and help you choose the right air conditioner for the size of the room to be cooled. If you're concerned about the costs of running an air conditioner, the Energy Guide label should be your primary source of information.
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