Furnace BTU Sizing Calculator by Square Footage
Furnace BTU by square footage is an early heat-loss screen. The working calculator adds design temperature difference, AFUE, margin and airflow checks.
furnace btu sizing calculator by square footage furnace size calculator by square footage heating btu calculator
Area heat-loss screen
q_loss = area * load_factor * deltaT_design / 70F
AFUE input rating
q_input = q_output / AFUE
Airflow check
CFM = BTU_per_hour / (1.08 * temperature_rise_F)
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