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The Proper Way to Size an Air Conditioner

blue-question-markBefore the 1980s, the general philosophy about air conditioning was pretty simple: Bigger is better.

At the time, it made sense. The air conditioner that cools your home down the fastest is the winner. Nowadays, we understand that this is an expensive way to operate an air conditioner (and it was none other than the homeowner who had to foot the bill).

Air conditioners in the present day are all about efficiency—cooling down the home at the most reasonable rate while using the least amount of energy. However, this is only possible when the air conditioner is sized properly.

In this post, we’ll go over a few ways that an HVAC technician should be sizing your unit. The symptoms of improperly sized units mimic those of other AC problems, so it’s not surprising that many homeowners mistakenly call for air conditioning repair in Fort Wayne, IN. In truth, the only thing that can fix an improperly sized unit is a full replacement.

Square Footage

The total square footage of your home is essential for sizing an air conditioner. For every square foot of space, the AC should output around 20 British thermal units (Btu).

However, this is not the only factor of sizing a unit. In fact, the reason a lot of air conditioning installations go bad is that the unit was sized purely on square footage. Although square footage is huge in estimating the size of the unit, there are several other factors that, if ignored, will result in your unit being oversized or undersized.


Where you live in the nation is another important factor in the amount of power your AC unit needs. As you could imagine, a hotter climate requires more cooling power than a colder climate. A powerful air conditioner is just a fact of life for a state like Arizona, where regions like Indiana require less cooling power (however, keep in mind that the cold season will require more heating power!).

This is important to take note of if you’re moving across the country and are planning to get an AC at your new home—you wouldn’t want to use the power ratings of your old AC to try and make a judgment about what your new AC’s power requirements and costs. Simply start fresh with new measurements.

Sunlight and Occupants

Two factors you might not immediately suspect go into sizing a unit are the amount of sunlight in the rooms and the number of average occupants in the rooms to be cooled.

The amount of power required will fluctuate depending on if the rooms in the home are heavily shaded or very sunny through most of the year. The number of windows in the home can directly affect this.

As for the number of occupants, it’s a fact that people generate heat. If you’re a family of four and regularly congregate in the living room, you’ll have to take that into consideration in your calculations.

Don’t let anyone size your air conditioner on square footage, alone! Contact Collier’s Comfort today if you’re considering installing a new air conditioner.

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