Kenmore 721.86012 Installation Instructions Manual page 9

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.
Below are the standard fittings and their equivalent length in feet.
3 1/4" x 10" to 6" = 5 ft.
90˚elbow = 10 ft
To calculate the equivalent length of each duct piece used, see the examples below.
For 3-1/4" x 10" SYSTEMS
3-1/4"x10"
3-1/4"x10"
90˚ elbow
90˚ elbow
2ft.
2ft.
1 3-1/4" x 10" 90° elbow
1 Wall Cap
8 feet straight duct
TOTAL LENGTH
STEP 2:
PREPARE THE VENTING SYSYTEM
3 1/4" x 10" roof cap = 24 ft
3 1/4" x 10" wall cap
= 40 ft
6ft.
wall cap
6ft. wall cap
= 25 ft.
= 40 ft.
= 8 ft.
= 73 ft.
45˚elbow = 5 ft
Figure 9
Examples
For 6" ROUND SYSTEMS
90˚ elbows
90˚ elbows
transition
transition
1 transition
2 90º elbows
1 Wall Cap
8 feet straight
TOTAL LENGTH
3 1/4" x 10" 90˚ elbow = 25 ft
3-1/4" x 10" flat elbow
= 10 ft
wall cap
6ft. wall cap
6ft.
2ft.
2ft.
=
=
=
=
=
5 ft.
20 ft.
40 ft.
8 ft.
73 ft.
9