Installation Instructions For External Exhaust Ducting
NOTE: If you need to install ducts, note that the total duct
length of 3 -1/4 in. x 10 in. (8.2 x 25.4 cm) rectangular or
5 in. (12.7 cm) diameter/ 6 in. (15.2 cm) diameter round duct
should not exceed 140 equivalent feet (42.7 m).
Outside ventilation requires an external 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 exhaust adaptor has been designed to mate with a
standard 3 -1/4 in. x 10 in. (8.2 x 25.4 cm) rectangular duct.
Duct pieces
Rectangular-to-Round
Transition Adaptor*
Wall Cap
90° Elbow
45° Elbow
90° Elbow
45° Elbow
Roof Cap
Straight Duct 6 in.
(15.2 cm) Round or 1/4
in. x 10 in. (8.2 x 25.4
cm 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.
If a round duct is required, a rectangular-to-round transition adaptor
must be used. A5 in. (12.7cm)/ 6 in. (15.2cm) diameter duct is
acceptable to use.
Maximum duct length:
For satisfactory air movement, the total duct length of 3-1/4 in. x 10 in.
(8.2 x 25.4 cm) rectangular or 5 in. (12.7 cm) diameter/6 in. (15.2 cm)
diameter round duct should not exceed 140 equivalent feet (42.7 m).
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.
Equivalent length
5 ft (1.5 m)
40 ft (12.2 m)
10 ft (3 m)
5 ft (1.5 m)
25 ft (7.6 m)
5 ft (1.5 m)
24 ft (7.3 m)
1 ft (0.3 m)
Total Ductwork
Equivalent lengths of duct pieces are based on
actual tests and reflect requirements for good
venting performance with any vent hood.
15
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Equivalent
Length
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