Unit Heater, Hydronic 150,000 BTU, Dragon Breath Wood Boiler *High Quality*
In order to find out which unit heater suits your needs, use the basic formula of 4,000 BTU’s per 100 sq. ft. Consider more or less BTUs based on geography and buildings insulation. For “0” insulation and greenhouses, use the 6,000 BTU’s per 100 sq ft formula.