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.
General information
NUMBER
EQUIVALEN
T LENGTH
EQUIVALEN
T LENGTH
DUCT PIECES
USED
Rectangular-to-Round
Transition Adaptor*
5
*
x
=
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 3…" x 10"
Rectangular
1 Ft.
x
( )
=
Ft.
Total Du ctw ork
=
F t.
Maximum duct length:
For satisfactory air movement, the total duct length of 3
1/4
"x10" 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.
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 made with a standard 3
1/4
"x10" rectangular duct.
If a round duct is required, a rectangular-to-round transiting adaptor must be used.
Do not use
less than a 6"diameter duct.
