John Kaylor, age 9, of Asheville, N.C., for his question:
HOW DOES AN AIR CONDITIONER WORK?
There are three types of air conditioning systems: the summer air conditioning equipment that cleans, cools and removes moisture from the air, the winter air conditioner that cleans, heats and adds moisture to the air, and the year around air conditioner that cleans and controls the temperature and moisture content of air throughout the year.
All air conditioning systems have some way of blowing or circulating the conditioned air through the rooms of a house or office building. An air conditioner brings fresh air into a room and pushes out stale air.
Cleaning the air can be accomplished in a number of different ways. Some air conditioners force the air through filters.The filters are usually made of closely packed fiber glass wool or metal fibers that have been coated with a sticky oil or some other type of adhesive. As the air passes through, the dirt, dust and soot in the air stick to the fibers.
Air can also be cleaned by blowing it through sprays of water called air washers. An air conditioner that uses this method has a row of nozzles that squirt a fine mist of water into the air. The water rinses out the dirt.
Some equipment uses electrostatic filters or electrostatic precipitators. These devices put a positive electrical charge on the particles of dirt in the air.
Still other air conditioners force the air through porous pieces of carbon, which absorb odors.
After an air conditioner cleans the air, it must cool it in the summer and heat it in the winter. Most provide an air temperature that is between 72 and 78 degrees Fahrenheit.
Refrigeration machines are used in many modern air conditioners to cool the air.Most air conditioners used in large buildings heat air by blowing it over coils filled with hot water or steam. A boiler heated by gas, oil burner or even coal produces the hot water or steam. Electric heaters are used to warm the air in other air conditioners.
Air conditioners can also be equipped to either add moisture to the air or to dehumidify it. Controlling the moisture helps to make an air conditioned room more comfortable.
An air conditioner also must circulate the air, since most people feel uncomfortable in motionless air that is being either heated or cooled. Fans blow conditioned air through the rooms with the air being moved through ducts that lead to various parts of a building.
An air conditioner can circulate air through a room at a rate of about 15 to 40 cubic feet per minute. The amount of air circulated depends on the size and speed of the fan.