Bottom Return Fan Connections; Plenum Fan Duct Connections; Draw-Thru Plenum Fan Discharge; Panel Cutting - Carrier Aero 39MN Series Installation, Start-Up And Service Instructions Manual

NOT LESS THAN 2-1/2
TIMES FAN DIAMETER
SUPPLY DUCT
30°
MAXIMUM
DUCT TRANSITION
Fig. 34 — Duct Connections

BOTTOM RETURN FAN CONNECTIONS

IMPORTANT: For all sizes with full bottom return
openings, attach ductwork to inside of baserails.
Return air ducts must be attached directly to the return side
of the unit. This applies to both indoor and outdoor units! Use
care when making turns and transitions in ductwork to avoid
excessive air friction. Duct elbows should contain turning
vanes. See Fig. 33.
PLENUM FAN DUCT CONNECTIONS — Plenum
are designed for draw-thru or blow-thru operation. Draw-thru
fan sections have closed panels on all sides except for the fan
inlet side. On blow-thru fan sections, the panel on the end op-
posite the inlet is omitted so that components such as coil or fil-
ter sections can be added downstream from the plenum fan.
NOTE: Duct openings cannot be cut into the bottom of any
plenum fan section. An additional discharge plenum MUST be
used for bottom duct opening.
DRAW-THRU PLENUM FAN DISCHARGE FABRICA-
TION — Discharge openings are not allowed through the
floor of plenum fan sections. A separate discharge plenum is
the only approved method for bottom duct connections when
using a plenum fan. Duct openings for draw-thru plenum fans
must be field fabricated. They should be located in the plenum
fan section according to the following guidelines:
• Locate discharge openings in side or top panels; the end
panel opposite the inlet will have a higher pressure drop
per the explanation in the 39M Product Data manual.
• Locate discharge openings on the side or top panels
between the fan wheel and end panel opposite the inlet.
Do not locate discharges in the direct path of airflow
from the wheel.
• Avoid locating the discharge opening on the motor side
of the fan section. If a discharge on the motor side is
necessary, locate the opening near the top of the cabinet.
• Sizes 36-110 include intermediate frame members.
When cutting the discharge opening for the plenum fan,
do not cut through any intermediate frame member.
Typical duct locations are shown in Fig. 35.
Once the discharge locations are selected and cut, the duct
connections can be fabricated. Install field-supplied duct flang-
es and framing channels to smooth the airflow leaving the dis-
charge opening. Two of the channels should extend the width
or height of the cabinet to provide additional cabinet support.
Panel Cutting —
filled panels require special attention when cutting and/or pene-
trating.
1. Take care in planning before penetrating any panel
2. In some cases it will be possible for smaller conduits
A39-2260
3. Drill a small pilot hole completely through the panel.
4. Use of a sharp hole saw or, if appropriate, a powered
fans
5. Carefully remove the foam. The hole should be lined
NOTE: Small quantities of locally available commercial
canned foam may be used, if necessary, to complete minor
repairs. Significant patching may justify ordering replace-
ment panels instead.
Face and Bypass Dampers —
damper sections are shipped fully assembled. Unit sizes 03-12
are built with a single damper assembly. Sizes 14-110 have
multiple damper assemblies linked via a jackshaft: two assem-
blies for sizes 14-61; three for sizes 72-96; and four for size
110. Damper crankarms have 90 degrees of travel from fully
open to fully closed positions and are adjustable to suit condi-
tions. Refer to Fig. 36 for details.
Removal of crankarms is necessary for direct connection actua-
tor use. Refer to Table 26 for linkage configurations. Refer to
Table 27 for operating torque requirements.
94
The 39M unit's double-wall foam-
with electrical conduit, hydronic piping, sensor pick-
ups or wiring. Once these are routed through a panel,
for all practical purposes, it becomes a fixed panel that
is not easily removed for service access.
( / -in. or / -in.) to enter the cabinet through the frame
1 3
2 4
rail where individual sections are joined together. In-
spect the selected area carefully to be certain that you
do not encounter shipping blocks or section joining
screws. Once the conduit is in place, it must be secure-
ly sealed, watertight and airtight, to prevent ANY infil-
tration.
Penetrations are typically located in one of the existing
"fixed" panels, such as the fan discharge panel or the
coil connection panel, to maximize the number of re-
movable/service panels. When it is necessary to pene-
trate the panel for wiring or piping entry, make certain
that the entry point will not interfere with future com-
ponent servicing, block access doors, or obstruct air-
flow.
shear cutting tool or sheet metal nibbler to cut the hole
or opening from each side.
CAUTION
Do not use a cutting torch or open flame on or near the fan.
Damage to the panel may occur.
or sleeved to confine the foam, and the penetration
should be sealed, both inside and out, to eliminate all
possibility of infiltration or leakage.
Actuators must be mounted directly to the damper shaft.
Table 26 — Linkage Configurations
LINKAGE CONFIGURATION
Top-Bottom
Top-Rear
Top-Face*
Rear-Bottom
Side-Rear
NO-LINKAGE CONFIGURATION
Side-Bottom
SIDE-TOP
* Sizes 50-110 use one actuator per damper.
All face and bypass
1 Actuator
1 Actuator Per Damper