What is Tonnage?
Plain-English explanation from a licensed Utah HVAC, plumbing, and electrical contractor.
Tonnage is the cooling-capacity measurement of an AC or heat pump, 1 ton equals 12,000 BTU/hr of heat removal, which is what one ton of melting ice would absorb in a 24-hour period.
Full Definition
HVAC tonnage measures cooling capacity in 12,000 BTU/hr increments. The term originates from the historical equivalence between one ton of ice melting in 24 hours and the rate of heat absorption from a space, exactly 12,000 BTU/hr. Residential AC and heat pump systems are typically sized in half-ton increments from 1.5 to 5 tons (18,000 to 60,000 BTU/hr). Equipment over 5 tons is considered light commercial.
On Utah's Wasatch Front, the old rule-of-thumb of '1 ton per 500 sq ft' is almost always oversized. Properly Manual-J-sized systems in modern construction often come in at 1 ton per 700-900 sq ft, especially in well-insulated post-2010 homes.
Common Questions
What size AC do I need for a 2,000 sq ft Utah home?
Without Manual J, a typical answer is 2.5-3 tons, but the right answer depends on insulation, window area, sun exposure, and elevation. Always do a load calculation before sizing.
Is a bigger AC better?
No. Oversized ACs cycle on and off rapidly, never run long enough to remove moisture, and wear out compressors faster. A properly sized unit runs longer at low capacity and delivers better comfort.
Related Terms
SEER
SEER is the cooling-efficiency rating of an air conditioner or heat pump, the higher the SEER number, the less electricity it uses per ton of cooling delivered over a typical Utah summer.
Manual J Load Calculation
Manual J is the industry-standard whole-house heat-loss and heat-gain calculation that determines exactly how big your furnace and AC need to be, too big or too small both hurt comfort and efficiency.
BTU
A BTU is the standard unit of heat in U.S. HVAC, one BTU is the energy needed to raise one pound of water by one degree Fahrenheit. Furnaces and ACs are rated in BTU per hour.
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