You hear a lot about how much energy your HVAC system uses, but what does that mean? How is that energy used? What do you get from it in terms of comfort? The heat energy of both your AC and your furnace is measured in BTUs. Here’s a look at how BTUs work in your HVAC system.

What Are BTUs? Learn How BTUs Work.

A BTU (or British Thermal Unit) measures how much heat it takes to do everything from lighting a match to boiling water to getting your home to its ideal temperature. If you heat 1 pound of water one degree Fahrenheit, you’ll have used one BTU of heat.

Both heating and cooling a space require heat energy, so how BTUs work applies to furnaces and ACs. In furnaces, BTUs measure how much heat the unit provides. In ACs, they measure how much heat the unit takes away over a given period.

BTUs and Tonnage

Your HVAC system’s capacity is measured in tons. It takes 1 ton of cooling per hour for every 600 square feet of your home, give or take, so for an 1,800-square-foot home, you’d need an AC with a 3-ton capacity. Tons of what, though? It’s BTUs.

To melt a 1-ton block of ice takes 286,000 BTUs over 24 hours, or 12,000 BTUs per hour. Therefore, every 12,000 BTUs your furnace delivers equals 1 ton of heating, and every 12,000 BTUs your AC removes equals 1 ton of cooling.

To determine how many BTUs your system uses, look for the label on the side of the unit. Many model numbers include a two-digit number between 18 and 60. That indicates how many thousand BTUs your system is (i.e., 18 = 18,000 BTUs). For the unit’s tonnage, divide that number by 12. Both numbers are important in determining how much energy your system uses, as well as whether or not the unit is the correct size for your home.

To learn more about how BTUs work and what it means for your home, contact us at Mowery Heating, Cooling and Plumbing. Indianapolis trusts us for quality home-comfort solutions.

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