Efficiency guide
The numbers on an HVAC quote decide how comfortable you'll be and how much energy you'll use for the next 15 years. Here's what they mean.
BTU
British Thermal Unit — the heat needed to raise one pound of water by 1°F. Cooling capacity is measured in BTUs per hour.
1 Ton
12,000 BTU/h of cooling. A "3-ton" system delivers about 36,000 BTU/h at rated conditions.
SEER2
Seasonal cooling efficiency under updated 2023 test procedures. Higher means less electricity for the same cooling.
HSPF2
Heating efficiency for heat pumps. Higher means more heat per unit of electricity.
Rough sizing range
Rules of thumb give a wide range. The real number depends on windows, orientation, insulation, duct location, and how many people live there — which is why we run a Manual J calculation. Slide to see how wide the guess can be.
Rule-of-thumb range
1.5–4.5 tons
That's a spread of 3 tons for the same house. A Manual J narrows it to a single, defensible number.
Illustration only, based on common 400–1,200 sq ft per ton rules of thumb. Not a substitute for a load calculation.
Current
— kWh/yr
New
— kWh/yr
Estimated cooling energy reduction: —
Assumes 2,400 full-load cooling hours per year, a rough figure for Central Florida. Real results depend on installation quality, ductwork, thermostat settings, and weather.
Efficiency comparison
Efficiency ratings compare how much electricity two systems use to deliver the same cooling. Enter your system's details to see the difference in estimated annual cooling energy.
Remember: a high-SEER2 system installed with leaky ducts or the wrong charge won't reach its rating. Installation matters as much as the label.
Design standards
Manual J
Calculates how much heating and cooling each room — and the whole house — actually needs.
Manual S
Selects equipment whose real capacity at local conditions matches the Manual J load.
Manual D
Designs ductwork so each room gets the airflow it needs, quietly.
Manual T
Chooses and places supply registers and return grilles for even air distribution.