49-80329 Rev. 5
5
Installation Preparation
DUCT FITTINGS
This Hood Must Use an 8” Round
Duct. It Can Transition to a
3-1/4” x 12” Duct.
Use this chart to compute maximum permissible lengths
for duct runs to outdoors.
NOTE:
Do not exceed maximum permissible equivalent
lengths!
Maximum duct length: 100 foot for range hoods.
Flexible ducting
If flexible metal ducting is used, all the 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.
NOTE:
Any home ventilation system, such as a
ventilation hood, may interrupt the proper flow of
combustion air and exhaust required by fireplaces, gas
furnaces, gas water heaters and other naturally vented
systems. To minimize the chance of interruption of such
naturally vented systems, follow the heating equipment
manufacturer’s guidelines and safety standards such
as those published by NFPA and ASHRAE. When
applicable, install any makeup (replacement) air system
in accordance with local building code requirements. Visit
GEAppliances.com
for available makeup air solutions.
Duct Piece
Dimensions
Equivalent
Length*
Quantity
Used
Total
Equivalent
Length
Round,
straight
1 ft. (per foot
length)
3-1/4” x 12”
straight
1 ft. (per foot
length)
90° elbow
17 ft.
45° elbow
10 ft.
3-1/4” x 12”
90° elbow
43 ft.
3-1/4” x 12”
45° elbow
26 ft.
3-1/4” x 12”
90° flat
elbow
102 ft.
8” round to
3-1/4” x 12”
transition
2 ft.
3-1/4” x 12”
to 8” round
transition
5 ft.
8” round to
3-1/4” x 12”
transition 90°
elbow
6 ft.
3-1/4” x 12”
to 8” round
transition 90°
elbow
13 ft.
Round wall
cap with
damper
32 ft.
3-1/4” x 12”
wall cap with
damper
75 ft.
Round roof
cap
44 ft.
* Actual length of straight duct plus duct fitting
equivalent. Equivalent length of duct pieces
are based on actual tests conducted by GE
Appliances Evaluation Engineering and reflect
requirements for good venting performance
with any ventilation hood.
Total Duct Run
1” = 2.5 cm; 1’ = 0.3 m
