5
Installation Preparation
36" Vent Hood
Duct
fittings
Total
Equivalent Quantity Equivalent
Duct Piece Dimensions
Length*
Used
Length
Round,
1 ft.
straight
(per foot
length)
3-1⁄ 4" x 10"
1 ft.
straight
(per foot
length)
90
°
elbow
15 ft.
45
°
elbow
9 ft.
3-1⁄ 4" x 10"
90
°
elbow
15 ft.
3-1⁄ 4" x 10"
45
°
elbow
9 ft.
3-1⁄ 4" x 10"
90
°
flat elbow
20 ft.
6" round to
3-1⁄ 4" x 10" or
3-1/4" x 24" transition
1 ft.
3-1⁄ 4" x 10"
to 6" round transition
5 ft.
6" round to
3-1/4" x 10"
transition 90
°
elbow
5 ft.
3-1⁄ 4" x 10" to 6" round
transition 90
°
elbow
15 ft.
Round
wall cap
with damper
30 ft.
3-1⁄ 4" x 10" wall cap
with damper
30 ft.
Round
roof cap
26 ft.
Round
roof vent
24 ft.
Use this chart to
compute maximum
permissable lengths
for duct runs to
outdoors.
Note:
Do not exceed maximum
permissable 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.
These Hoods Must
Use 6" Round Duct
* Actual length of straight duct plus duct fitting
equivalent. Equivalent length of duct pieces are based
on actual tests conducted by GE Evaluation Engineer-
ing and reflect requirements for good venting
performance with any ventilation hood.
Total Duct Run