GE JNM3163 Installation Instructions Manual page 5

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 120 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.
DUCT PIECES
Rectangular-to-Round
Transition Adaptor*
Wall Cap
90° Elbow
45° Elbow
90° Elbow
45° Elbow
Roof Cap
Straight Duct 6" Round or
3¼" x 10" Rectangular
* 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.
Installation Instructions
EQUIVALENT
LENGTH x
5 Ft.
40 Ft.
10 Ft.
5 Ft.
25 Ft.
5 Ft.
24 Ft.
1 Ft.
5
Maximum duct length:
For satisfactory air movement, the total duct length of
3¼" x 10" rectangular or 6" diameter round duct should
not exceed 120 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.
NUMBER
USED
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
Total Ductwork =
Equivalent lengths of duct pieces are based on actual tests
and reflect requirements for good venting performance with
any vent hood.
EQUIVALENT
= LENGTH
=
=
=
=
=
=
=
=
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.