BTU = pounds of water × 1°F temperature change
BTU = 8.33 × gallons of water × 1°F temperature change
BTU = 500 × airflow in CFM × temperature difference in °F
BTU/hr = watts × 3.412
watts = BTU/hr ÷ 3.412
BTU/hr = horsepower × 2545
horsepower = BTU/hr ÷ 2545
BTU = mass × specific heat × temperature change
BTU = lb × °F change × specific heat factor
BTU/hr = room area × heat load factor
BTU/hr = length × width × ceiling height × load factor
BTU/hr = total heat gain ÷ time in hours