Central Air Conditioners
Central air conditioners remove heat from the air of an entire building through the use of a compressor, a condenser, an expansion valve, a thermostat and motorized fans. Central air conditioning units are connected to air ducts that deliver cool air throughout the house, office, school or other structure. The popular belief about air conditioning is that it introduces cold air into a warm area when in reality it removes heat from the air, which makes it feel cooler. This is similar to evaporative cooling.
The components that make up central air conditioning units are made from metal such as aluminum or stainless steel because they are strong, durable and are able to dissipate heat well. Air conditioner manufacturers fabricate air conditioners in varying sizes; units range from the size of an average moving box to the space of a walk-in closet. For residential buildings, the unit is usually placed beside the structure; for industrial or commercial systems the units are on top of the roof. Central air conditioning units are used in buildings where fans or natural breezes are inadequate because of temperature, air disturbance or pollution. They are used in residential buildings, industrial plants, factories, businesses, vehicles and many other places where cool air creates a more comfortable environment.
Central air conditioning units have a thermostat that senses the current air temperature and when it reaches a predetermined temperature, the unit turns on until the thermostat measures the air temperature at a lower level. Air conditioning units use a chemical called a refrigerant that can change quickly from a gas to a liquid; Freon is the most common. This chemical is contained inside coils within the body of the main unit. The compressor causes the refrigerant to change from a cool gas to a hot gas under pressure. As the gas runs through the coils, it condenses into a liquid as the heat dissipates. It is forced through the small opening of the expansion valve, which helps it evaporate back into a cold low-pressure gas. This gas runs through the coils to absorb heat from the air, cooling the space. Central A/C is more efficient than some other models such as a window mounted unit; it is able to cool the whole house. Like all air conditioning units and systems, central air requires electricity. If other measures are taken to reduce heat in the space such as keeping doors closed, using shades on windows and fixing insulation issues, the cost will be much lower. It is easy to install because it can use the same duct system that the furnace uses. Other air conditioning systems include portable air conditioners, split air, industrial, ductless or commercial.