Overview The Ventis HEI170 medium sized wood burning insert is recommended for heating smaller spaces from 500 - 1, 800 sq. ft. The firebox is lined with refractory bricks for better heat distribution. The HEI170 offers non-catalytic combustion technology, and a Stainless-steel secondary-air system which improves gas combustion. This unit has a 6hr Maximum Burn Time, can hold 18" logs and is EPA 2020 approved. Features 1.9 cu. ft. firebox Heating capacity 850 to 1, 800 sq. ft. Optimum efficiency : 78% Non-Catalytic Combustion Technology Cast Iron Doors Optimum efficiency : 78% Emissions: 1.26 g/h BTU/hr, seasoned cord wood: 65,000 1.9 cu. ft. firebox Heating capacity 850 to 1, 800 sq. ft. Optimum efficiency : 78% Non-Catalytic Combustion Technology Cast Iron Doors Optimum efficiency : 78% Emissions: 1.26 g/h BTU/hr, seasoned cord wood: 65,000 Manuals Owner's Manual Spec Sheet Drawing Dimensions