Carrier 39T, Installation, Start-Up And Service Instructions Manual

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Inlet Guide Vane Actuators, Plenum Fans —
Inlet guide vanes (IGVs) are available as an option on ple-
num fans. They must be adjusted in the field as follows.
POSITION ACTUATOR — The inlet guide vanes are opened
and closed by a field-supplied actuator. See Table 17 to cal-
culate actuator torque requirements for each fan size and type.
The actuator drives a factory-supplied crankarm and linkage
that moves the vanes open and closed. Using a field-
supplied mounting bracket, mount the actuator to the floor
of the plenum fan section near the inlet so that the connect-
ing rod from the actuator and the crankarm are on the same
plane and so that the crank arm moves without binding. See
Fig. 33 for crankarm location on linkage.
CHECK LINKAGE — Adjustment holes are provided in
the actuator crankarm; adjust the connecting rod from the
actuator and the crankarm on the IGV linkage so that the
vanes move together from the fully open to fully closed po-
sitions at zero and full stroke.
Do not force inlet guide vanes past the fully open or
fully closed positions.
Table 17 — Plenum Fan IGV Actuator Torque
Requirements
39T
UNIT
SIZE
FAN
SIZE
FAN
DIAMETER
(in.)
FAN
CLASS
A* B* C*
11-17 Standard 18,20,22 I, II 1.32 1.00 1.98
21
Small 24 I, II 1.19 1.17 2.13
Standard 27 I, II 1.09 1.34 2.28
26,32
Small 27 I, II 1.09 1.34 2.28
Standard 30 I, II 0.98 1.55 2.46
39
Small 33 I, II 0.89 1.78 2.66
Standard 37 I, II 0.81 2.00 2.86
49
Small 37 I, II 0.81 2.00 2.86
Standard 40 I, II 0.73 2.14 3.29
61
Small 40 I, II 0.73 2.14 3.29
Standard 45
I 0.55 2.91 2.96
II 0.47 3.39 2.54
74
Small 45
I 0.55 2.9I 2.96
II 0.47 3.39 2.54
Standard 49
I 0.37 4.46 2.42
II 0.33 5.02 2.15
92
Small 54 I, II 0.30 5.64 2.32
Standard 60 I, II 0.27 6.43 2.52
*Use to calculate torque requirements for a given plenum fan and fan
wheel, using the following formula:
Total Torque Required (in.-lb) = A (
cfm
)
2
+ B x ESP + C,
1000
where cfm is the design airflow and ESP is the external static pres-
sure (in. wg).
Plenum Fan Duct Connections —
Refer to the manu-
facturer’s Installation, Operation, and Maintenance instruc-
tions taped to the fan cabinet. Plenum fans are designed for
draw-thru (PAF3) or blow-thru (PAF5) 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 opposite the inlet is omitted so that components such
as coil or filter sections can be added downstream from the
plenum fan.
DRAW-THRU PLENUM FAN DISCHARGE FABRICA-
TION — 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 39T Product Data manual.
• Locate discharge openings on the side or top panels be-
tween 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 nec-
essary, locate the opening near the top of the cabinet.
Typical duct locations are shown in Fig. 34.
Once the discharge locations are selected and cut, the duct
connections can be fabricated. Install field-supplied duct flanges
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 sup-
port. See Fig. 34.
CRANK
ARM
Fig. 33 — IGV Crankarm and Linkage, Plenum Fans
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