The BTU, short for British Thermal Unit, is the standard for measuring units of heat. It’s an important specification, because moving heat is an air conditioner’s main function. It extracts heat energy inside your home and moves it outdoors, where it’s dispersed into the air. What’s left behind is a cool, comfortable house.
The BTU specification represents the amount of heat an AC can move in an hour. It’s usually expressed in tons (one ton equals 12,000 BTUs of heat). Most residential air conditioners are rated from 1.5 tons to 5 tons (from 18,000 to 60,000 BTUs), with the exact capacity depending on square footage of the home and other additional factors like sun exposure, insulation, and number of windows. A qualified HVAC contractor can perform a sizing survey, then utilize industry-standard software to calculate the proper cooling capacity in BTU tons.
Why Accurate Sizing Is Critical
Guesswork or “rule of thumb” sizing isn’t accurate enough to meet today’s standards for energy efficiency and cooling performance. In fact, air conditioners that are too small or too large are both generally unsatisfactory when it comes to monthly operating costs and indoor comfort.
There’s no fix for an undersized or oversized AC. Once it’s installed, you’re stuck with the consequences until a new unit replaces it. Here’s what’s wrong with both too small and too large BTU capacity:
- An air conditioner with BTU capacity that’s too small for the house won’t cool adequately. What’s worse, it will run extended cooling cycles, sometimes running nearly nonstop, which wastes energy and increases cooling costs while indoor comfort remains substandard.
- When BTU capacity exceeds home requirements, the air conditioner “short cycles,” turning on and off rapidly before the house is ever uniformly cooled to the proper temperature. Short cycling also impedes the air conditioner’s dehumidifying function, so indoor humidity rises and the house feels clammy. Wear and tear caused by short cycling also takes its toll on critical components like the compressor.
Talk to the pros at Paitson Bros. for more about how air conditioner BTUs impact home cooling and operating costs. We’ve been your go-to source for reliable HVAC information for 100 years.
Jeff Paitson is a third generation business owner who continues to run the business with the same values that have been passed down from previous generations since 1922.
Jeff’s belief is that the business belongs to Jesus Christ; therefore 10 percent of the company’s profits go toward the Maryland Community Church.
Jeff is a Terre Haute Chamber of Commerce member and in his spare time, he enjoys 
Ethan Rayburn is a lifelong resident of Terre Haute and a 2005 graduate of Purdue University.
An Eagle Scout, Ethan spent four years as a non-profit executive with the Boy Scouts of America before joining Paitson Bros. as a comfort advisor and later General Manager. In that role, Ethan has brought a renewed enthusiasm for customer care, integrity, value, and service to Paitson Bros. Heating & Air Conditioning.
Ethan enjoys singing and was a member of the Purdue Varsity Glee Club. He also enjoys playing and coaching soccer, spending time with his family and two young boys, and volunteering his time and resources with his church, Terre Haute First Baptist Church, which he has attended from a very young age.
Paitson Bros
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