At 420,000 BTU/hour, the Thaw Devil ground-heating unit can thaw up to 6000 square feet, 1 foot deep per day. It also cures up to 12,000 square feet per application. Its modular design includes a built-in fuel supply, low-pressure heating system, and a low-fuel shutoff. No special boiler certification necessary. Heat Wagon. 888-432-8924.