GE JVM1540 Installation Instructions Manual page 5

Installation Instructions
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 caIefldly.
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
uansition 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 120 equivalent feet.
Elbows, transitions, wall and roof caps,
etc.,
present additional resistance to airflow and are
equivalent to a section of smdght duct which is longer
than their actual physical size. When calcula6ng the
total duct length, add the equivalent lengths of all
uansi6ons and adaptors plus the length of all suaight
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
G
O
m
Rectangular-to-Round
TransitionAdaptoP
Wall Cap
90° Elbow
45° Elbow
90° Elbow
45° Elbow
RoofCap
Straight Duct6" Roundor
3¼" x 10" Rectangular
EQUIVALENT
LENGTH
5 Ft.
40 Ft.
10 Ft.
5 Ft.
25 Ft.
5 Ft.
24 Ft.
1 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 ti"ee movement of the damper.
NUMBER
x USED
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
x ( )
Total Ductwork
EQUIVALENT
= LENGTH
=
=
=
=
=
=
=
=
==
Equivalent lengths of duct pieces are based on actual tests
and reflect requirements tbr good venting pertbrmance with
_l_) r veIlt tlood,
5
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.
Ft.