This guide is educational. Local design conditions, codes, utility tariffs, manufacturer instructions, and site measurements control a real project.
Capacity is not floor area alone
Square-foot rules miss windows, orientation, shading, air leakage, insulation, occupants, ventilation, ducts, ceiling height, and local design weather. A room-by-room load calculation turns those conditions into sensible and latent cooling loads.
Oversizing creates its own problems
A large system can satisfy the thermostat quickly while leaving humidity behind and delivering short, noisy cycles. It may also require duct airflow the house cannot support. Correct sizing aims for long, steady operation near design conditions while maintaining indoor humidity and air distribution.
Review the selection, not just the load
The calculated load is followed by equipment selection. Ask for the proposed unit’s certified sensible and latent capacity at the actual design conditions and airflow. Nominal tons are labels; delivered performance depends on outdoor temperature, indoor conditions, coil match, and airflow.
Verify after installation
Commissioning should document refrigerant charge, temperature change, electrical readings, total external static pressure, filter pressure drop, condensate operation, controls, and airflow. Keep the report with the equipment model and warranty records.
Turn the guide into numbers with our free HVAC calculators, then compare the result with itemized local bids.