Super quiet operation. Totally enclosed condenser motor for long life rated for 30,000 hours continuous run. Easy installation. Rustproof paint treatment on galvanized housing. Built-in damper to prevent backdraft. Fits in 2 x 8 construction. Thermal fuse protection on motor and 3-level safety device for heater. Durable stainless steel sheathed heating element. Quick 1 minute warm-up. 3 year warranty. ASHRAE 62.2, LEED for Homes, ENERGY STAR IAP, CA Title 24, EarthCraft and WA Ventilation Code compliant. Minimum 20 Amp dedicated circuit recommended. For optimum performance, install heater no more than 8 feet from floor to ceiling