Amazon offers Master 32,000-BTU LP Tank Top Space Heater (MH-32-TTC) for with free shipping.

Product Description: 
The Master® propane tank top space heater is perfect for job sites, farms and emergencies (no electricity required!), but it also warms you up for camping, fishing, tailgating and hunting. Mounted directly to the top of a 20-pound propane tank, this durable heater has a small footprint and is ultra-portable. It uses radiant-style heat, features match-light ignition, and it's wind resistant.