Z-Flex 4" x 40' Aluminum Liner Kit v600 glass with cast iron frame

glass with cast iron frame Glass type Ceramic glass Glass surface – dimensions (Width X Height) 10 1/4" x 8 7/8" Glass air-wash system Yes Overall dimension (Height) 28

Why is the BTU according to EPA test data smaller than the one advertised

Only one penetration is needed through the roof or the wall for both exhaust and combustion air

10’ Length

Z-Flex 4" x 40' Aluminum Liner Kit v600 glass with cast iron frameUL listed aluminum chimney liner kit for use with Category I natural draft gas fired heating equipment and gas fireplaces. Note: For Use with Natural Draft Appliances. Not intended for use with Category II, III, or IV gas burning appliances as defined by the National Fuel Gas Code, NFPA 54, or other appliances that result in condensation or corrosive acids on the liner of the chimney, or that create positive pressures in the chimney system.