This informative guide will tell you everything you need to know to find the perfect air conditioner for your home.

What type of air conditioner do I need?



Air conditioners come in four main types: window units, through the wall units, portable units and whole house/central air units. Window units come in three main flavors: double-hung windows, sliding windows and casement windows.

Window units will usually convert between types with special hardware, which is often included. Small through the wall units will often convert into window units. Large through the wall, and central air units usually require professional installation, which adds to the cost.

What features do I need?

You should expect the unit to have an adjustable thermostat, at least two cooling speeds, two fan speeds and an energy efficient setting, which stops the fan when the unit is not cooling. The unit should have an adjustable vent, which allows you to aim the cool air, and an exhaust vent setting allowing fresh air to be introduced from outside. The filter should be easily accessible for removal and cleaning. You want a manufacturer's warrantee for at least 5 years, with full replacement for at least 1 year.

Some of the newer units have an electrostatic filter available either standard or as an option. This filter will remove extremely small particles from the air. This is a super feature for people with allergies.

What is EER?

EER or Energy Efficiency Ratio is a measure of how efficient a particular air conditioning unit is. The higher the number, the more efficient the unit and the less it will cost each year to run. Small units currently have a top EER of about 11, while the most efficient large units have an EER of about 13. Don't be fooled by the ranges shown on the yellow tags. The top rated units are often beyond the range.

What cooling capacity do I need?

Cooling capacity is measured in BTU/hour. (British Thermal Units per Hour) The higher the number, the more powerful the unit is. A small room of 150 square feet may only need a 5000 BTU/Hour unit, whereas a room of 1200 square feet may need a 19,000 BTU/Hour monster.

However, room size is not the only factor that contributes to the capacity. There are many other factors including:

· the number and size of the windows
· the direction the room faces
· the available shade
· how well the room is insulated
· how many people use the room
· what appliances (computers etc.) are in the room

The little chart the salesman uses is woefully inadequate. The easiest way to calculate the required size is to use one of the on-line guides. There are many available. Look to see what figures the guide of your choice requires, then measure your room. I liked the one in the free area of the Consumer Reports site best:

Which AC should I buy?

You should buy the unit of the correct capacity and type that has the highest EER, if you can afford it. Buying a unit of lower EER that costs less is usually a false economy. However, in areas with very short cooling seasons, or extremely cheap power, a lower cost unit may be a good buy