Hood exhaust
When venting exhaust to the oustside, hood exhaust ducts will be required. 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 31A"x 10" (82 x 254
mm) rectangular duct. If a round duct is required, a rectangular-to-round
transition
adaptor must be used. Do not use less than a 6" (152 mm) diameter duct.
Maximum
Duct Length
For satisfactory air movement, the total duct length of 31A" x 10" (82 x 254 mm)
rectangular or 6" (152 mm) diameter round should not exceed 120 equivalent
feet (36,5 m).
Elbows, transitions,
wall and
roof caps etc.
cause 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
Duct Pieces
Equivalent Length
x
used
Equivalent Length
Rectangular-to-Round
Transition Adaptor*
5ft(1,5m)
=
ftorm
Wall Cap
40 ft (12,2 m)
90° Elbow
1Oft (3 m)
45 ° Elbow
5 ft (1,5 m)
90° Elbow
25 ft (7,6 m)
45 ° Elbow
5 ft (1,5 m)
Roof Cap
24 ft (7,3 m)
=
ftorm
=
ftorm
=
ftorm
=
ftorm
=
ftorm
=
ftorm
29