4
31-7000091 Rev. 1
Installation Instructions
EQUIVALENT
NUMBER
DUCT PIECES
LENGTH
x
USED
=
LENGTH
Rectangular-to-Round
5
Ft.
x (
)
= Ft.
Transition Adaptor*
Wall
Cap 40
Ft.
x (
)
= Ft.
90°
Elbow
10
Ft.
x (
)
= Ft.
45°
Elbow
5
Ft.
x (
)
= Ft.
90°
Elbow
25
Ft.
x (
)
= Ft.
45°
Elbow
5
Ft.
x (
)
= Ft.
Roof
Cap 24
Ft.
x (
)
= Ft.
Straight Duct 6″ Round or
1 Ft.
x
( )
=
Ft.
3
1
⁄
4
″ x 10″ Rectangular
Total
Ductwork
= Ft.
Equivalent lengths of duct pieces are based on actual tests
and reflect requirements for good venting performance with
any vent hood.
*
IMPORTANT: I
f a rectangular-to-round transition
adaptor 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.
NOTE:
If you need to install ducts, note that the total
duct length of 3
1
⁄
4
″ x 10″ rectangular or 6″ diameter round
duct
should not exceed 140 equivalent feet.
Outside ventilation requires a HOOD EXHAUST DUCT.
Read the following carefully.
NOTE:
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 mate with
a standard 3
1
⁄
4
″ x 10″ rectangular duct.
If a round duct is required, a rectangular-to-round
transition adaptor must be used.
Do not use less than
a 6
″
diameter duct.
Maximum duct length:
For satisfactory air movement, the total duct length of
3
1
⁄
4
″ x 10″ rectangular or 6″ diameter round duct
should
not exceed 140 equivalent feet.
Elbows, transitions, wall and roof caps,
etc.,
present additional resistance to airflow and are
equivalent to a section of straight duct which is longer
than their actual physical size. When calculating the total
duct length, add the equivalent lengths of all transitions
and adaptors plus the length of all straight duct sections.
The chart below shows you how to calculate total
equivalent ductwork length using the approximate feet of
equivalent length of some typical ducts.