GE JGP989 Owners Manual - Page 20

Installation Instructions DUCTWORK CALCULATIONS Calculate Total Equivalent Ductwork Length Duct Pieces Equivalent Number Equivalent Length* x Used = Length 6″ round straight 1 ft. x ( )† = ft. 31⁄4″ x 10″ straight 1 ft. x ( )† = ft. 6″, 90° elbow 15 ft. x ( ) = ft. Duct Pieces Equivalent Number Equivalent Length* x Used = Length 6″ round to 31⁄4″ x 10″ transition 90° elbow 20 ft. x ( ) = ft. 31⁄4″ x 10″ to 6″ round transition 5 ft. x ( ) = ft. 31⁄4″ x 10″ to 6″ round transition 90° elbow 12 ft. x ( ) = ft. 6″, 45° elbow 9 ft. x ( ) = ft. 6″ round wall cap with damper 21 ft. x ( ) = ft. 24″ max. flexible metal offset adapter 34 ft. x ( ) = ft. 31⁄4″ x 10″ 90° elbow 16 ft. x ( ) = ft. 31⁄4″ x 10″ 45° elbow 5 ft. x ( ) = ft. 31⁄4″ x 10″ 90° flat elbow 18 ft. x ( ) = ft. 31⁄4″ x 10″ wall cap with damper 27 ft. x ( ) = ft. 6″ round roof cap 20 ft. x ( ) = ft. 6″ round roof vent 24 ft. x ( ) = ft. Subtotal Column 2 = ft. Subtotal Column 1 = ft. TOTAL DUCTWORK = ft. 6″ round to 31⁄4″ x 10″ transition 7 ft. x ( ) = Subtotal Column 1 = Should not exceed 100 feet. ft. DO NOT use flexible plastic ducting. Vent installation should not exceed 100 feet ft. equivalent length. *Equivalent lengths of duct pieces are based on actual tests and reflect requirements for good venting performance with any downdraft cooktop. †Measure and list feet of straight duct used. Count and list the quantity of all other duct pieces for the "Number Used" of each type. IMPORTANT: For maximum efficiency, use the shortest and straightest duct run possible, with as few fittings as possible. For satisfactory performance, the duct run should not exceed 100 feet equivalent length. Venting performance is improved by using larger diameter duct. 20