How many BTUs of heating capacity do you need?
The formula below can serve as a rough guide for determining the heat requirements for common building applications:
BTU Required = Square footage x Ceiling Height x ?t x Building Factor
Where t = Temperature Rise (Desired Temp. F inside – Outside Temp F)
Building Factors: .135 (Sealed building), .145 (Unsealed building), .160 (Tent)
Example: A 4000 sq. ft. unsealed building has an 8′ ceiling height. The desired temperature
is 70° F and the outside temperature is 30° F. Therefore,the desired temperature rise (???? t) is 40°.
BTU Required = 4000 x 8 x 40 x .145 = 185,600
Other factors to consider are insulation, ventilation, and the number of rooms being heated. After determining the most suitable type of heater and the BTU requirements for your application, select a heater (or heaters) with a BTU rating equal to (or greater than) your requirements.