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GENERAL INFORMATION
If you need to install ducts, note that the total duct length of 3
1
/
4
"
x 10" (8.3 x 25.4 cm) rectangular or 6" (15.2 cm) diameter round
duct should not exceed 140 equivalent feet (42.7 m).
Outside ventilation requires a HOOD EXHAUST DUCT. Read
the following carefully.
It is important that venting be installed using the most direct
route and with as few elbows as possible. This ensures clear
venting of exhaust and helps prevent blockages. Also, make
sure dampers swing freely and nothing is blocking the ducts.
EXHAUST CONNECTION
The hood exhaust has been designed to connect with a standard
3
1
/
4
" x 10" (8.3 x 25.4 cm) rectangular duct.
If a round duct is required, a rectangular-to-round transiting adapter
must be used. Do not use less than a 6" (15.2 cm) diameter duct.
MAXIMUM DUCT LENGTH
For satisfactory air movement, the total duct length of
3
1
/
4
"x 10" (8.3 x 25.4 cm) rectangular or 6" (15.2 cm) diameter
round duct should not exceed 140 equivalent feet.
ELBOWS, TRANSITIONS, WALL AND ROOF
CAPS, ETC.
Elbows, adapters, wall and roof caps, etc. present additional resis-
tance to air flow and are equivalent to a section of straight duct which
is longer than their actual physical size. When calculating the total
length, add the equivalent lengths of all transitions and adapters
plus the length of all straight duct sections. The chart on the right
shows the approximate measurement of equivalent length of some
typical ductwork parts.
Use the values in the chart for calculating total ductwork, which
should be less than 140 equivalent feet (42.7 m). Equivalent lengths
of duct pieces are based on actual tests and reflect requirements for
good venting performance with any vent hood.
IMPORTANT:
If a rectangular-to-round transition adapter is used,
the bottom corners of the damper will have to be cut to fit, using the
tin snips, in order to allow free movement of the damper.
DUCT PIECES
EQUIVALENT
LENGTH X
NUMBER USED
EQUIVALENT
LENGTH
EXAMPLE ONLY (VALUES)
Rectangular-to-Round
Transition Adapter
5 ft (1.5 m)
x (1)
5 ft
(1,5 m)
Wall Cap
40 ft (12.19 m)
x (1)
40 ft
(12.19 m)
90˚ Elbow
10 ft (3 m)
x (1)
10 ft
(3 m)
45° Elbow
5 ft (1.5 m)
x (1)
5 ft
(1.5 m)
90° Elbow
25 ft (7.6 m)
x (1)
25 ft
(7.6 m)
45° Elbow
5 ft (1.5 m)
x (1)
5 ft
(1.5 m)
Roof Cap
24 ft (7.3 m)
x (1)
24 ft
(7.3 m)
Straight Duct
(3 ¼" x 6" Round )
1 ft (30.5 cm)
x (5)
5 ft
(1.5 m)
Example Total Ductwork 119 ft (36.3 m)
