Vermont Castings Merrimack Features EPA Certified 350 sq. inch of viewing area Automatic Air Setback System- which provides extra air over the top of the fire to speed up to start up procedure. Variable speed fan Options Northfields cast iron in Classic Black Extra steel in Classic Black Specifications Max. BTU: Up to 55,000 Approx. Heating Area: Up to 2,000 sq. ft. Burn Time: Up to 12 hrs Log Size: Up to 22" Firebox Capacity: Up to 40 lbs Efficiency: 75% Flue Size: 6" Price: $0.00 Updating cart...