What Size AC Do I Need for My Home?

Whether you’re living in a tiny home or a large ranch, figuring out the right size AC unit can be a challenge. If you’re not familiar with AC jargon, words like BTU and ton can get confusing.

To figure out how to cool your space effectively and with efficiency, let’s dive into a bit of backstory about how systems sizes are rated and why it’s important. From there, you can know what to look for and hopefully, enlist the assistance of a good contractor to get the job done.

How the Size of a System is Rated

Air conditioning sizes are rated in tons of cooling capacity. Essentially, a mathematical formula is used that converts the weight of ice into energy. A “ton” of air conditioning represents approximately 12,000 BTU per hour. This means that a 3-ton air conditioning system will have 36,000 BTU per hour — a 4-ton air conditioning system will have 48,000 BTU per hour (and so so forth).

If you hear someone using the term ton, remember that it doesn’t refer to the weight of the equipment itself. The word actually comes from a time when before electric air conditioning even existed — when folks would cool their homes with blocks of ice that were harvested from lakes and rivers in the wintertime. The ice would absorb the heat and then melt as it warmed up.

Why AC Size is Important

AC size is crucial because if your system is too small it won’t cool, and an oversized system can lead to humidity issues. To ensure that your system runs smoothly and keeps your energy costs low, you want to make sure you have the right sized unit!

When the system is too big it won’t run a full cycle but will instead go on and off (which will end up costing you extra money). On the other hand, when it’s too small, it will always be running (which will also cost you extra money). If it’s just right, the system will move through a cooling cycle efficiently and then turn off when it’s done — which will save you money and conserve energy.

On average, the right sized system can be calculated with the following equation: square footage of your home multiplied by 30 and dived by 12,000 minus 1.0. This will give you the required tonnage needed for your unit.

What a Good Contractor Will Do

A good contractor will perform ACCA Manual J to determine the correct size/capacity of your unit. Using a checklist, they’ll identify key elements that impact the overall function of your unit — like indoor and outdoor design temperatures, windows, glass doors, large skylights, insulated walls, and more. Manual J helps contractors perform accurate calculations and ensures that you, as a homeowner, are getting the right sized unit for your space and environment.

Keep in mind, if you need help figuring out what size unit your home requires, Air Authority is here for you! For all your air conditioning needs, feel free to reach out to us.

From the team at Air Authority, thanks for reading! Wishing you a cool day ahead.