How to Size Unit Heaters

Unit heaters are a very basic and affordable way to provide heat to spaces that might not be heated otherwise. Garages, barns, shops, greenhouses, etc. are all examples spaces that can benefit from the versatility of a unit heater.

Figuring out how large of a unit heater you need is quite simple. (This is really the bare bones version of BTU equations. These numbers are good for estimating but are not exact.)

Required BTU = Length x Width x Height x Insulation Factor

The insulation factors are as follows:

4x - good insulation
5x - average insulation
7x - poor insulation

Generally it’s better to err on the side of caution and oversize a unit heater for your particular space. Also, be sure to account for large windows or doors that don’t have matching insulation values.

Example

A pole barn with average insulation (5x factor) that is 60' long, 40' wide, and has a 12' ceiling:

The BTU to heat this building would be as follows:
60 x 40 x 12 x 5 = 144,000 (BTU required)

The best unit heater for this space would be a UH-140 (158,000 BTU).

Be sure to check out the new Hawken Energy Store to find the unit heater that’s right for you. Contact your local Factory Rep for distributor direct pricing!

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