EQUIVALENT
NUMBER
EQUIVALENT
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.
6
* 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.
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
duct pieces.
Installation Instructions
1” = 2.5 cm; 1’ = 0.3 m
