Installation guide

STEP 2: PREPARE THE VENTING SYSTEM
STANDARD FITTINGS
NOTE: If the existing duct is round, you must use a rectangular-to-round adapter, with a rectangular 3"
extension duct installed between the damper assembly and the adapter to prevent the exhaust
damper sticking.
DUCT LENGTH
The total length of the duct system, including straight duct, elbows, transitions, wall or roof caps must not
exceed the equivalent of 140 feet.
For best performance, do not use more than three 90 degree elbows, and keep length as short as possible.
Below are the standard fittings and their equivalent length in feet.
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3-1 /4"x10" to 6" = 5ft. 3-1/4"x10" roof cap = 24ft. 3-1/4"x10" 90° elbow = 25ft.
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Ss 2
90° elbow = 10ft. 3-1 /4"x10" wall cap = 40ft. 45° elbow = 5ft. 3-1/4"x10" flat elbow = 1 Off.
Figure 10
To calculate the equivalent length of each duct piece used, see the examples below.
I
Examples
For 3-1/4"x10" SYSTEMS For 6" ROUND SYSTEMS
je 6ff. ——»|_- Wall cap 90° elbows — fa—— ft, ——» /
“yf K Wall cap
3-1/4"x10" t
90° elbow ait Transition
13-1/4" x 10" 90° elbow == 25 ft. 1 transition = 5 ft.
1 wall cap = AO fi. 2 90° elbows = 20 ft.
8 feet straight duct = 8 ft. 1 wall cap = AO ft.
TOTAL LENGTH = 73 ft. 8 feet straight = 8 ft.
TOTAL LENGTH = 73 ft.