Air conditioner sizing: get it right before you buy or you may regret it for as long as you own the unit. “Sizing” in the HVAC sense doesn’t refer to physical dimensions. It means the capacity of the air conditioner; i.e., the amount of cooling it can produce expressed as BTUs of heat energy extracted from the air per hour.
The Capacity For Cool
Every air conditioner comes with a size rating. For example, a standard residential central A/C for a 2,000 square foot home in our climate zone might be sized at 3 “tons” of cooling capacity. Each ton of capacity = 12,000 BTUs per hour, so that unit is rated to extract 36,000 BTUs of heat from the house every hour.
Sizing Up Your House
But how much heat actually needs to be removed to keep your specific home comfortably cool? Square footage is only a very rough guideline that should never be the only factor. Every house is different. Variables include:
- Basic floor plan
- Daily sun exposure
- Type of insulation
- Number of occupants
- Air-tightness of the structure
- Number of windows
All the above comprise a comprehensive figure known as the home’s “cooling load.” Expressed in BTUs per hour, the cooling load represents the exact amount of air conditioner capacity required to keep the house comfortable on a typical hot summer day.
Why Load Matters
Cooling load is determined by a formal load calculation conducted by a qualified HVAC professional utilizing industry-standard load software. A precise load calculation gives the HVAC contractor the data needed for accurate air conditioner sizing— matching an A/C with the appropriate cooling capacity to meet the unique cooling requirements of your home. Rough guesstimates or rule-of-thumb averages aren’t good enough. Installing an over-sized or under-sized air conditioner means sub-standard cooling performance, higher monthly operating costs, poor air quality and greater wear and tear on system components. These negatives will persist until the unit is replaced.
For more about the importance of proper air conditioner sizing, contact Paitson Bros., your local source for trusted HVAC advice since 1922.
Our goal is to help educate our customers in Terre Haute, Indiana about energy and home comfort issues (specific to HVAC systems). For more information about other HVAC topics, download our free Home Comfort Guide or call us at 812-645-6859.
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
1 (812) 232-2347
Serving the Wabash Valley, IN Area Since 1922