5
General information
NOTE: If you need to install ducts, note that the total duct
length of 3¼” 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 3¼” 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 3¼”
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.
DUCT PIECES
EQUIVALENT
LENGTH
x
NUMBER USED
=
EQUIVALENT
LENGTH
Rectangular-to-Round
Transition Adaptor*
5 ft.
x
( )
=
ft.
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
3¼” x 10” Rectangular
1 ft.
x
( )
=
ft.
Total Ductwork
=
ft.
* IMPORTANT: If 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.
Equivalent lengths of duct pieces
are based on actual tests and reflect
requirements for good venting performance
with any vent hood.
DE68-03587B-EN.indd 5
2008-12-09 �� 4:13:01
