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Air Conditioner Guide: Everything You Need to Know About Air Conditioners

Air Conditioner

In the dog days of summer, most people choose to remain indoors rather than brave hot sidewalks and sunburns. But when the first serious heat wave arrives and shelter can't even be found indoors, stores sell out of relief in hours, sending hundreds of air conditioners on their way. As a result, people will often purchase whatever is available, with little regard for its specifications to the buyer's needs-- even that yellow-tinged sputtering job in the back of the local hardware store. Many people don't head to the store with home measurements and electric bills in hand and, as a result, end up with something that just doesn't quite fit. But with a little preparation it is possible to purchase a unit that meets the needs of both the consumer and the space, whether it's an entire duplex or one small bedroom.

Air Conditioner Basics

Air conditioners have both cooling and heating mechanisms. The cooling half blows cool air into the room, while the heating mechanism involves venting hot air out of the room. All types of air conditioners function according to this basic principle and are made up of the same basic components. The compressor compresses the coolant and raises pressure and temperature. The hot coolant runs through hot condenser coils in order to dissipate heat and condense into a liquid. An expansion valve causes the coolant to expand and evaporate into a cool gas, and then the low temperature coolant runs through cold evaporator coils, cooling the surrounding air. Fans are also a main component of air conditioners as they constantly circulate inside air over the cool coils and blow outside air over the hot coils, dissipating heat more effectively.

An air conditioner's power capacity is generally rated in BTUs, or British Thermal Units, with most room air conditioners falling between 5,000 and 30,000 BTUs. The practical effectiveness of a unit may vary depending on outside factors including how many people are in the space being cooled, what other electronics are functioning within the space and outside temperature. In general, a 5,000 BTU air conditioner will effectively cool a room of 100-150 square feet, 6,000 BTUs will cool a space of 150-250 square feet, 7,000 BTUs will cool a space of 250 to 300 square feet, and so forth. To estimate the necessary BTUs, find the square footage of the given space and multiply it by 35.

The recommended BTU rating, however, is not always applicable. For example, if the air conditioner will be in a room shaded from the outside, reduce the BTUs by 10%. If the space is exposed to ample sunlight, increase the BTUs by 10%. For a room that is regularly used by more than two people, add about 600 BTUs per person. For cooling a kitchen, add 4,000 BTUs (in consideration of heat generated by appliances such as the oven, stove and microwave.)

To find the EER, or energy efficiency rating of an air conditioner, divide the BTU rating by the wattage used. A higher EER means better energy efficiency, but also impacts the unit's price. Look for the Energy Star label to confirm a purchase with the most energy efficiency.

With the knowledge of different components and the importance of BTUs and EERs in the selection of the proper unit, the buyer must now decide which type of air conditioner will best suit his or her needs. The main difference between types of air conditioners is simply how the components are arranged, but knowing these differences can be especially important in deciding which unit is the correct choice.

Also in this article:
The Different Types of Air Conditioners
Air Conditioner Size, Strength, and Features