The size of the unit should be just large enough to cool the square footage but not be larger than needed. Therefore, the first thing to consider when choosing the best AC unit is the size of the house.
There is not a one-size fits all guide to what size unit a home will need. An experienced HVAC technician evaluates the home and the area to help an individual make the best choice. In the southern-most portion of the U.S., a 2.5 ton unit will cool 1,200 to 1,500 square feet. The same unit will cool a 1,400 to 1,650 square foot home in the northern-most states.
The size of an AC unit is measured by tonnage, and residential air conditioners can range from 1 to 5 tons. The efficiency of a unit is measured by the seasonal energy efficiency ratio. This is how much cooling a system will provide per dollar spent on utilities. The energy efficiency ratio is the ratio of the output to electrical power. A more efficient unit will have a higher SEER and EER rating than a lower one. Combined together, the two numbers represent the type of performance expected for typical weather in an area for any given year.
A higher rated AC unit will cost more money up front, but the unit will pay for itself over time in energy savings. An individual can also receive a tax credit for purchasing an energy-efficient HVAC unit.