Central Air Conditioner

All air conditioning systems reduce the temperature and adjust the humidity of the air in the home to levels that provide a level of comfort. The most common type of system used in the U.S. is the basic, air-cooled central air conditioning system. Another type of system, found primarily in the hot and arid areas such as the southwestern U.S., is known as an evaporator cooler or “swamp cooler”. Other, less common types include the water-cooled systems, gas chillers and geothermal systems.

How They Work

The common, air-cooled central air conditioner removes heat from the air in the home and moves the heat to the air on the exterior of the home. Air conditioners accomplish this by taking advantage of the basic physical law that heat moves to areas that are cooler. Heat from the interior of the home is transferred to a refrigerant that carries the heat to the exterior of the home. Currently the most effective refrigerant is freon. The warm air in the home is blown over an evaporator coil that contains cold (approximately 20 degrees F) freon liquid. The freon absorbs heat from the air in the house, which cools the air. The warmer (approximately 50 degrees F) freon, which has boiled and turned into a gas, is then moved to the exterior of the home where it disperses the heat.

The question is, "How is the heat dispersed when it is hot outside?" A gas or liquid, when compressed, will have a higher temperature. A compressor is used to compress the freon gas, increasing its temperature by approximately 100 degrees F and causing the freon to become much hotter than the air outside. The air outside (approximately 85 degrees F) can then be blown over the condensing coil that contains the hot freon (approximately 150 degrees F) . The air absorbs the heat from the compressed freon, in effect cooling it. The cooled, but still compressed freon (approximately 100 degrees F), is then returned to the house. To lower the temperature of the freon liquid even more, the freon is expanded or decompressed (to approximately 20 degrees F). The freon is then once again ready to absorb the heat from the air in the home.

Article published with permission from: U.S. Inspect