Timberwolf Economizer Series EPI22 25"" Natural Vent Wood Burning Fireplace Insert with Up to 65 000 BTU's EPA Certified Dual Blower System Full Refractory Lined Firebox and Heat Radiating Ceramic Glass Model #: EPI22 Outstanding 86% efficiency rating Can generate up to 65,000 BTUs and heat 800 to 2,000 sq. ft. Durable firebox with full refractory lining Two blowers with automatic thermodisc and speed control