Models range from 50,000 to 250,000 Btu/h (15 to 73 kW), 20 to 80 ft. (6 to 24 m) length systems, and highest mounting options up to 50 ft. (15 m);Emissive coated radiant tubes significantly improve the thermal efficiency of infrared heaters;High-efficiency EC Motor technology with 85% motor efficiency and advanced whisper-quiet operation;Factory-installed turbulators and mounted ignitor