DCS HBD1200E Installation Instructions Manual page 15

Plan the ductwork
The internal blower can be mounted to the front or back of the downdraft unit and be
ducted in multiple directions: left, right, down, forward or backwards. The remote blower
can be ducted downwards from the front or back of the downdraft unit.
In the event of installations where the blower is located on the back of the downdraft unit,
it is advised to leave an access door or opening to reach the bottom of the downdraft
unit, as well as where the wiring box and blower is located should service be needed.
Calculate the duct run length
The ductwork length should not exceed 55 equivalent feet (16.7 m) for 6" (152 mm)
round duct, or 75 equivalent feet (22.9 m) for 10" (254 mm) round duct. Calculate the
length of the ductwork by adding the equivalent feet listed in the table below for each
piece of duct in the complete system. If flexible metal ductwork is used, each foot
(312 mm) of flexible metal ductwork is equivalent to two feet (617 mm) of straight metal
ductwork when calculating the duct run length.
For best results the size of the ductwork should be uniform and use no more than
three 90° elbows. Make sure that there is a minimum of 24" (607 mm) of straight
duct between elbows if more than one is used. Round duct is recommended instead
of rectangular duct especially if elbows are needed. Rectangular duct should be
transitioned to minimum 6" (152 mm) round for internal blowers and 10" (254 mm)
round for remote blowers as soon as possible.
EQUIVALENT LENGTH
45° elbow
90° elbow
90° flat elbow
Wall cap
INSTALLATION INSTRUCTIONS
5 feet (1.5 m)
7 feet (2.1 m)
12 feet (3.7 m)
0 feet (0.0 m)
EXAMPLE CALCULATION
9 feet straight duct
2 x 90° elbows
Wall cap
Complete system
EN
9 feet (2.8 m)
14 feet (4.3 m)
0 feet (0.0 m)
23 feet (7.0 m)
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