IM708 9
Duct Connections
Supply Air
For connection of supply ductwork directly to the unit, a
duct collar must first be mounted at the fan outlet, avoiding
the mounting screws located around the perimeter of the fan
discharge opening (see Figure 8). Fan discharge opening
sizes are indicated on the unit dimensional drawings. When
connecting ductwork to the unit, a canvas type connecting
collar is recommended.
Units are available in two fan configurations and should be
ducted as shown in Figure 9. Duct take-offs which go oppo-
site to the direction of fan rotation will result in an associated
system effect loss and reduced fan performance.
If a field fabricated plenum is used, duct take-off locations
should again be correctly oriented to the rotation of the fan to
minimize system losses. Refer to unit dimensional drawings
and Figure 8 for plenum mounting size requirements. Can-
vas type connectors are recommended at the duct connection
to the plenum.
Units are also available with a factory provided discharge
plenum. Supply duct connections to the plenum opening(s)
should include a canvas type connector. Plenum opening
sizes and locations will be indicated on the job submittal.
Figure8. Unit top detail
Figure9. Discharge duct configurations
Return Air
Return air to the unit can be arranged in two ways.
1. Ducted return
Return ductwork may be attached to the 2" flange around the
perimeter of the unit's return air opening (Refer to Figure
10). A canvas type duct connecting collar is recommended.
All ductwork connected to the unit should be of adequate
size and construction for the application. A canvas type con-
nector is also recommended where the duct penetrates the
machine room wall(s). This will prevent vibration generated
by air movement in the duct from being transmitted out to
the occupied spaces.
Note: Do not obstruct unit access panel located below the
return opening.
2. Free return
The mechanical equipment room may be used as a return
plenum with no hard connection at the unit.
Note: Some building codes do not allow the use of the
mechanical room as a return plenum. Applicable
local codes should be checked for each installation.
Figure10.Back Elevation
M
2.0”
2.0” Typical
29”
D
B
K x L
Return Air Opening
Mechanical
Access
(See Notes)
(Optional)
Multi-Directional
Plenum
(See Notes)
1” Neoprene
Isolation Pads,
Shipped Separately
B25
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