AC Capacity: Why Cooling Equipment Is Measured in Tons

When discussing AC capacity, it’s often easiest to understand when comparing it to a tasty pound cake. When pound cakes gained popularity in the United States, they were made with a pound each of eggs, butter, sugar and flour. The designation “one pound” was simply a way for bakers to remember the recipe.

Air conditioners can relate to this, as AC capacity is referred to in “tons.” Many homes feature 3 or 4-ton air conditioners, but this doesn’t mean that the units weigh 3 or 4 tons. The number refers to the amount of heat the air conditioner must remove from a home every hour to keep it cool and comfortable.

Where Did the “Tons” Come From?

Before engineer Willis Carrier invented modern-day air conditioning in 1902, ice from lakes and rivers was used to remove heat from indoor spaces. Carrier knew that if you took one ton of ice—which equals 2,000 pounds—and wanted to melt it uniformly over a span of 24 hours, it would require a total of 286,000 British thermal units, (BTUs). This factors out to be about 12,000 BTUs per hour.

Just like that somewhat misleading “pound cake,” the word “ton” stuck, and air conditioning experts still use it today. So if you need a 4-ton air conditioner, you don’t need one that weighs 8,000 pounds. You need one that removes 48,000 BTUs of heat per hour from your home.

So what, you may ask, goes into calculating the AC capacity necessary to cool a home? Many factors, including its square footage, quality of insulation, rate of air leakage and orientation to the sun. It’s not exactly a piece of cake, but there is a formula to figuring out just the right recipe for your home’s AC tonnage.

The pros at Scott’s Heating & Air Conditioning can help make sure your system is the right size for your home.  We’re proud to serve homeowners throughout the Orlando area and Central Florida.

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Scott’s Heating & Air Conditioning is a full-service heating and air conditioning company and a Bryant® Factory Authorized Dealer in Central Florida. Whether you need repair, maintenance, or installation of a new heating or cooling system, we provide efficient, cost-effective, and professional service. When it’s hot, call Scott!

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