Installation Instructions

5
Advanced Planning
DUCT FITTINGS
Total
Equivalent Quantity Equivalent
Duct Piece Dimensions Length* Used Length
Round, 1 ft.
straight (per foot
length)
1 ft.
3-1/4" x 12" (per foot
straight length)
90° elbow 15 ft.
45° elbow 9 ft.
3-1/4" x 12"
90° elbow 15 ft.
3-1/4" x 12"
45° elbow 9 ft.
3-1/4" x 12"
90° flat elbow 20 ft.
8" round to
3-1/4" x 24" transition 1 ft.
3-1/4" x 12"
to 8" round transition 5 ft.
8" round
to 3-1/4" x 12"
transition 90° elbow 5 ft.
3-1/4" x 12" to 8"
round transition 90° elbow 15 ft.
Round
wall cap
with damper 30 ft.
3-1/4" x 12" 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.
Total Duct Run
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.
*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.
This Hood Must
Use 8" Round Duct
It Can Transition to
3-1/4" x 12" Duct