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Installation Instructions
13
DUCTWORK LENGTH AND DUCT FITTINGS
NOTE: Do not exceed 150 foot maximum permissible equivalent lengths!
Flexible ducting: If flexible metal ducting is used, all equivalent feet values in the table should be
doubled. The flexible metal duct should be straight and smooth and extended as much as possible.
DO NOT use flexible plastic ducting.
Add equivalent lengths for all duct pieces and transitions used to ensure that the duct run does not
exceed the maximum 150 feet.
Duct Equivalent Duct Equivalent Duct Equivalent
Pieces Length* Pieces Length* Pieces Length*
3
1
⁄4″ x 10″
to 6″ Round
6″ Round 1 ft. (per 3
1
⁄4″ x 10″ Transition
4 ft.
Straight foot length) 45° Elbow
8 ft.
90° Elbow
6″ Round
3
1
⁄
4
″ x 10″ 1 ft. (per 3
1
⁄
4
″ x 10″ Wall Cap 24 ft.
Straight foot length) 90° Flat Elbow
33 ft.
with Damper
6″ Round 3
1
⁄4″ x 10″
6″ 12 ft. to 3
1
⁄4″ x 10″ 2 ft. Wall Cap 24 ft.
90° Elbow Transition with Damper
3
1
⁄
4
″ x 10″
6″ to 6″ Round 2 ft. 6″ Round
45° Elbow
7 ft.
Transition Roof Cap
33 ft.
6″ Round
to 3
1
⁄4″ x 10″
3
1
⁄4″ x 10″ Transition
4 ft.
90° Elbow
14 ft.
90° Elbow
SHOULD NOT EXCEED 150 EQUIVALENT FEET
*Equivalent lengths of duct pieces are based on actual tests conducted by GE Evaluation Engineering
and reflect requirements for good venting performance. See chart for CFM Duct Length.