DUCT PIECES
E
QUIVALENT
LENGTH X
NUMBER
USED =
EQUIVALENT
LENGTH
6" (15.2cm) Round
Straight **
1 Ft. (0.3m)
Ft. or m
6" (15.2cm) Round Metal Flex
No Bends **
1.5 Ft. (0.45m)
Ft. or m
6" (15.2cm)
90° Elbow
10 Ft. (3m)
Ft. or m
6" (15.2cm)
45° Elbow
5 Ft. (1.5m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm)
Straight **
1 Ft. (0.3m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm)
90° Elbow
10 Ft. (3m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm)
45° Elbow
5 Ft. (1.5m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm)
90° Flat Elbow
10 Ft. (3m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm) to 6"
(15.2cm) Round Transition 90° Elbow
30 Ft. (9m)
Ft. or m
6" (15.2cm) Round to 3¼" x 10"
(8.2cm x 25.4cm) Transition
90° Elbow
30 Ft. (9m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm) to 6"
(15.2cm) Round Transition
5 Ft. (1.5m)
Ft. or m
6" (15.2cm) Round to 3¼" x 10"
(8.2cm x 25.4cm) Transition
5 Ft. (1.5m)
Ft. or m
6" (15.2cm) Round Wall Cap with
Damper
30 Ft. (9m)
Ft. or m
3¼" x 10" (8.2cm x 25.4cm) Wall
Cap with Damper
30 Ft. (9m)
Ft. or m
6" (15.2cm) Round Roof Cap
30 Ft. (9m)
Ft. or m
TOTAL DUCTWORK
Ft. or m
** For Straight Round / Rectangular Duct, measure actual linear feet
used and then multiply by Equivalent Length shown.
Calculating Duct Length Table
For maximum efficiency, use the shortest and straightest duct possible. The system will operate most efficiently when
the ductwork does not exceed 60 feet of equivalent duct. The downdraft will operate properly with ductwork up to 100
equivalent feet of duct.
Calculations are approximate and based on HVAC industry standards.
12
INSTALLATION
