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
12 ft.
Straight
foot length)
45° Elbow
5 ft.
90° Elbow
6
″
Round
3
1
⁄
4
″
x 10
″
1 ft. (per
3
1
⁄
4
″
x 10
″
Wall Cap
21 ft.
Straight
foot length)
90° Flat Elbow
24 ft.
with Damper
6
″
Round
3
1
⁄
4
″
x 10
″
6
″
15 ft.
to 3
1
⁄
4
″
x 10
″
7 ft.
Wall Cap
27 ft.
90° Elbow
Transition
with Damper
3
1
⁄
4
″
x 10
″
6
″
to 6
″
Round
5 ft.
6
″
Round
45° Elbow
9 ft.
Transition
Roof Cap
20 ft.
6
″
Round
to 3
1
⁄
4
″
x 10
″
3
1
⁄
4
″
x 10
″
Transition
20 ft.
6
″
Round
90° Elbow
16 ft.
90° Elbow
Roof Vent
24 ft.
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.
