Heater Sizing

Here are the key bits of information you will need if order to properly size a heater.

Proper job sizing is having as much information about your project as possible:

1. Cubic feet of structure (Length x Width x Height)? We cannot use square feet because we are needing to heat all the air in the structure.

2. Desired inside temperature?

3. What will be the average outside temperature during the heating process?

4. Available fuel source (Typically either propane or natural gas)

5. Available power source (120V, 240V, 480V – 1 or 3 phase)

6. Enclosure description (How tight is your enclosure – see descriptions below)

From here we will need to determine the TR = Temperature Rise

To figure temperature rise you will need to know the average outside temperature and the desired inside temperature. The difference between the two is the temperature rise.



Cubic Feet of Structure (30’ Wide x 50’ Long x 15’ High) = 22,500

Average outside temperature = -5°F

Desired inside temperature = 45°F

Temperature Rise = 50 (45 + 5 = 50)

Enclosure Description = Fairly Loose

Following the above graph across on the “Fairly Loose” line to the 50°F-TR = 3.9 (BTU PER CUBIC FOOT)

22,500 x 3.9 = 87,750 BTU’s (Size of Heater Needed)

*Graphs and enclosure descriptions courtesy of Heat Wagon*

This of course is just a brief overview of how to size temporary heating requirements for your job. There are other things to consider like length and size of supply hose, gauge of extension cord based on voltage required and length of cord need, size of propane tank needed, gas pressure, etc. For more in-depth information please refer to Heat Wagons’ Engineering Guide or call us here at Bierschbach Equipment & Supply and we would be happy to give you hand. We’ve added a link below.

Heat Wagon Engineering Guide

For purchase or rental information contact your local Bierschbach Equipment and Supply.