Twin City IM-4220 User Manual
Forward Curved Inline Duct Blowers
INSTALLATION, OPERATION & MAINTENANCE MANUAL
Twin City Fan & Blower Catalog 4220 provides additional information on this equipment. This catalog can be found
at www.tcf.com or by contacting your local Twin City Fan & Blower sales representative.
August 2014
IM-4220
Model DBS – 080 through 200 Model DBT – 080 through 200
Receiving, Inspection, & Unpacking
When the equipment is received all items should be
carefully checked against the bill of lading to be sure all
crates and cartons have been received. Before accepting delivery, carefully inspect each carton or crate for
visible shipping damage. If any damage is noticed, the
carrier should make the proper notation on the delivery
receipt acknowledging the damage. Make notations of all
damage on all copies of the bill of lading and have all
copies countersigned by the delivering carrier. The carrier should also fill out a Carrier Inspection Report. The
factory Traffic Department should then be contacted.
File claim for damage with the carrier. Physical damage
to the unit after acceptance is not the responsibility of
Twin City Fan Companies, Ltd.
Unpack each carton or crate and verify that all required
parts and proper quantities of each item have been
received. Refer to drawings for part descriptions. Report
shortages or missing items to your local representative
to arrange for replacement parts.
Due to availability of carriers and truck space, it is not
possible to guarantee that all items will be shipped
together. Verification of shipments must be limited to
only those items on the bill of lading.
The unit nameplate must be checked to make sure the
voltage agrees with the power supply available.
©2014 Twin City Fan Companies, Ltd.
General Installation
CAUTION: Sheet metal parts, screws, clips and similar
items inherently have sharp edges, and it is necessary
that the installer and service personnel exercise caution.
The installation of this equipment shall be in accordance
with the regulations of authorities having jurisdiction and
with all applicable codes.
Electrical Connection
This equipment is to be installed by an experienced
installation company and fully trained personnel.
The mechanical installation of the inline centrifugal fan
consists of making final connections between the unit,
building services, and duct connections.
1. Connect supply wiring to the disconnect switch
(non-fused standard). Check the wiring diagrams on
the motor for connections.
2. The motor is factory set at the voltage marked on
the fan nameplate. Check the line voltage with the
nameplate voltage and wiring diagrams.
3. The main power wiring should be sized for the
ampacity shown on the dataplate. Size wires in
accordance with the ampacity tables in Article 310
of the National Electrical Code. If long wires are
required, it may be necessary to increase wire size
to prevent excessive voltage drop. Wires should be
sized for a maximum of 3% voltage drop.
CAUTION: Use copper conductors only.
CAUTION: Protect wiring from sharp edges. Leave
some slack in the line to prevent damage.
4. Disconnect switches are not fused. The power leads
must be protected at the point of distribution in
accordance with the fan dataplate.
Check, Test & Start Procedure
WARNING
Electric shock hazard. Could cause severe injury or
death. Failure to bond the frame of this equipment
to the building electrical ground by use of the
grounding terminal provided or other acceptable
means may result in electrical shock. Disconnect
electric power before servicing equipment. Service
to be performed only by qualified personnel.
BEFORE START-UP: Disconnect power to this unit
before servicing the unit.
1. Check to verify that the wheel is free to rotate.
2. Verify that supply voltage on the line side of discon-
nect agrees with voltage on fan data plate and is
within the 10% utilization voltage.
3. Apply power to unit and check rotation of wheel with
the directional arrow on the unit. See Figure 1.
WARNING: Rotation is critical. If allowed to operate
in the wrong direction, the motor will overload and
burn out.
WARNING: Check units for rotation. For three-phase,
rotation can be changed by interchanging any two of
the three line leads. If unit is checked on temporary
5. On fans without a thermal protector integral to the
motor (refer to unit or motor dataplate to determine
if protector is present) a separate overload device
is required. Refer to Sections 430-32 of the N.E.C.
for sizing.
6. All units must be electrically grounded in accordance
with local codes or, in the absence of local codes,
with the latest edition of the National Electrical
Code (ANSI/NFPA 70). A ground lug is provided as
standard in the unit terminal box. Size grounding
conductor in accordance with Table 250-95 of the
National Electrical Code. DO NOT use the ground
lug for connecting a neutral conductor.
7. Supply voltage to the inline fan should not vary by
more than 10% of the value indicated on the unit
dataplate. Phase unbalance must not exceed 2%.
WARNING: Failure of motor due to operation on
improper line voltage or with excessive phase unbalance constitutes product abuse and may cause
severe damage to the unit’s electrical components.
wiring, it should be rechecked when permanently
installed. Motor burn-out or tripped overload protection devices are usually the result of wrong rotation.
4. Electrical Input Check: Perform check of fan ampere
draw and verify that motor nameplate amps are not
exceeded. Take into account the service factor range
if motor is nameplated above a 1.0 service factor.
5. Fan RPM should be checked and verified with a
tachometer.
NOTE: The fan was balanced at the factory to be
within stringent vibration levels before shipment.
However, there are several things that may cause
vibration, such as rough handling in shipment and
installation, weak foundations and alignments.
Figure 1. Fan Wheel Rotation
Rotation
Rotation
2 Twin City IM-4220
V-Belts
V-belts on these belt driven fans are oil, heat, and static
resistant type and oversized for continuous duty. With
proper installation and maintenance, years of operating
efficiency can be added to the lifespan of the V-belt
drive.
The condition of V-belts and the amount of belt tension should be checked prior to start-up (see Figure
2). When it becomes necessary to adjust belt tension,
do not over-tension as bearing damage will occur.
Recommended belt tension should permit
1
⁄64" deflection
per inch of span of the belt at the center of the belt
span. To find this point, measure halfway between the
pulley centerlines as shown in Figure 3. Extreme care
must be exercised when adjusting V-belts as not to misalign the pulleys. Any misalignment will cause a sharp
1. Where tensioning rods are not provided, adjustment is
more easily obtained by loosening and adjusting one
side of the motor bracket at a time.
2. Always loosen tension adjustment enough to place
belts on sheaves without running belts over the edge
of either sheave. A new belt may be seriously damaged internally by careless handling (see Figure 6).
WARNING: When removing or installing belts, never
force belts over pulleys without loosening motor first to
relieve belt tension.
3. Fan speed can be increased by closing the adjustable motor pulley or decreased by opening it. Always
check the load on the motor when increasing the fan
speed.
reduction in belt life and will also produce squeaky,
annoying noises (see Figure 4). On units equipped with 2
groove pulleys, adjustments must be made so that there
is equal tension on all belts (see Figure 5).
Figure 2. Eliminate Slack Figure 3. Belt Deflection
Belt Span
Slack belts wear excessively, cause slippage
and deliver less power. For longest belt life,
always provide proper tension
Figure 4. Mounting Belts Figure 5. Sheaves
CORRECT
INCORRECT
Mount belts straight. Shafts must be parallel
Figure 6. Belts
and sheaves in alignment to prevent unnecessary belt wear.
Deflection
Deflection =
64
Belt Span
Two-groove variable pitch
sheaves must be opened the
same number of turns on
both sides; otherwise, slippage occurs, wearing belts
rapidly,
Do not force belt. Forcing the belt will
break the cords and cause belt failure.
Twin City IM-4220 3
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