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
Fan Troubleshooting Chart
PROBLEM POSSIBLE CAUSES
FAN DOES NOT OPERATE 1. Wrong voltage.
2. Electricity turned off or not wired properly.
3. Tripped overload protector.
4. Blown fuses.
5. Loose pulleys.
6. Broken belts.
TOO LITTLE AIR 1. Wheel rotating in wrong direction.
2. Fan speed lower than design.
3. System is more restrictive (more static pressure) than expected.
4. Restricted fan inlet or outlet.
5. Inlet or outlet screens clogged.
6. Filters (if applicable) are dirty or clogged.
TOO MUCH AIR 1. Fan speed higher than design.
2. System is less restrictive (less static pressure) than expected.
EXCESSIVE HORSEPOWER 1. Wheel rotating in wrong direction.
2. Wheel rubbing on inlet venturi.
3. Fan speed higher than design.
4. Worn fan bearings.
EXCESSIVE NOISE 1. Wheel or sheaves loose.
2. Bearing or drive misalignment.
3. Accumulation of material on wheel.
4. Worn or corroded wheel.
5. Wheel out of balance.
6. Wheel hitting housing.
7. Bent shaft.
8. Bearings need lubrication.
9. Loose bearing bolts.
10. Loose or worn bearings.
11. Mismatched belts.
12. Belts too loose or too tight.
13. Belts oily or dirty.
14. Belts worn.
15. Loose fan mounting bolts.
16. Rattle of components in high velocity airstream.
17. Electrical noise.
18. Noise from high velocity air system.
19. Vibrating parts not isolated from building.
20. Vibrating ductwork.
EXCESSIVE VIBRATION 1. Wheel or sheaves loose on shaft.
2. Wheel out of balance.
3. Excessive buildup of dirt/dust on wheel.
4. Belts too loose or too tight.
5. Mismatched belts.
6. Bent shaft.
7. Bearing or drive misalignment.
8. Loose or worn bearings.
9. Fan mounting bolts loose.
10. Weak mounting base for fan.
11. Structures not cross-braced (wall fans).
12. Curb not flat and level.
It is recommended that the users and installers of this shipment familiarize themselves with AMCA Publication #201,
“Fans and Systems” and publication #202, “Troubleshooting” which are published by the Air Movement and Control
Association (AMCA), 30 West University Drive, Arlington Heights, Illinois 60004. www.amca.org
4 Twin City IM-4220
Maintenance
Installation and maintenance are to be performed only
by qualified personnel who are familiar with local codes
and regulations and experienced with this type of equipment.
CAUTION: Sharp edges and screws are a potential injury
hazard. Avoid them.
WARNING
Hazardous moving parts. Unit may contain pro-
tected fan motor which may start automatically
and cause injury. Allow time for reset. Disconnect
power before servicing.
Preventive maintenance is the best way to avoid unnecessary expense and inconvenience. Routine maintenance
should cover the following items:
a. Tighten all setscrews, bolts and wire connections.
b. Check belt tension and sheaves for wear.
c. Lubricate fan bearings (see Tables 1 and 2). Only bearings provided with fittings are intended to be relubricated.
d. Cleaning of unit, wheel and damper (if present).
All motors containing ball bearings are permanently
lubricated from the factory. No additional maintenance
is required.
1. Before performing any maintenance on the fan, be
sure power is turned off and locked in the OFF
position at the service entrance.
2. Fans should be carefully checked at least once a
year. For critical or rugged applications, a routine
check every two or three months is suggested.
3. For repairs within the warranty period, the motor
must be taken to the motor manufacturer’s authorized service dealer.
4. A periodic motor check should consist of spinning
the motor shaft with the power off to be sure the
motor turns freely and the bearings run smoothly.
The belt on belt driven units should be removed
from the motor sheave.
5. When removing or installing a belt, do not force
the belt over the sheave. Loosen the motor mount
so that the belt can be easily slipped over the
sheave.
6. The belt on belt driven units should be removed and
carefully checked for glazing, cracks, ply separation
or irregular wear. A small irregularity in the contact
surface of the belt will result in noisy operation. If
any of these defects are apparent, the belt should
be replaced. Check the sheaves also for chipping,
dents or rough surfaces which could damage the
belt.
7. The correct belt tension is important. Too tight of
a belt will result in excess bearing pressure on the
motor bearings and shaft pillow blocks and may
also overload the motor. Too loose of a belt will
result in slippage which will quickly “burn” out belts.
A belt should feel “live” when thumped, approximately
to finger pressure at midpoint between sheaves.
1
⁄4" belt deflection (3 to 5 lb.) when subject
8. The belt alignment should also be checked to be
sure the belt is running perpendicularly to the rotating shafts. Fan and motor shafts must be parallel. Improper alignment will result in excessive belt
wear.
9. Check sheave setscrews to ensure tightness. Proper
keys must be in keyways.
10. Do not readjust fan RPM. If sheaves are replaced,
use only sheaves of identical size and type.
11. If unit is to be left idle for an extended period, it is
recommended that belts be removed and stored in
a cool, dry place to avoid premature belt failure.
12. The standard bearings on Models DBS and DBT are
permanently lubricated and sealed. For pillow block
bearings lubrication annually is recommended, or more
frequently if needed (see Table 1).
It is recommended to add fresh grease at start-
up. Use only 2 or 3 shots of a recommended
lubricant with a hand gun in most cases (see Table
2). Maximum hand gun rating 40 P.S.I. Rotate bearings during lubrication where good safety practice
permits.
CAUTION: Greases of different soap bases
(lithium, sodium, etc.) may not be compatible when
mixed. Prevent such intermixing by completely purging the bearing of old greases.
The most frequent causes of bearing failure are
not greasing often enough, using an excessive
quantity of grease, or using incompatible greases.
Excessive vibration, especially if the bearing is not
rotating, will also cause bearings to fail. Bearings
must also be protected from water and moisture to
avoid internal corrosion.
13. During the first few months of operation it is recommended that the bearing setscrews be checked
periodically to ensure that they are tight.
14. The rotating wheel requires particular attention since
materials in the air being handled can build up on
the blades to cause destructive vibration or weaken
the structure of the wheel by corroding and/or eroding the blade metal. Regular inspection and corrective action at intervals determined by the severity of
each application are essential to good service life
and safety.
Table 1. Suggested Fan Bearing Greasing Intervals
INTERVAL
(MONTHS)
12 to 18 Infrequent operation or light duty in clean atmosphere.
6 to 12 8 to 16 hrs./day in clean, relatively dry atmosphere.
3 to 6 12 to 24 hrs./day, heavy duty, or if moisture is present.
temperatures; moisture laden atmosphere; vibration.
Heavy duty in dirty, dusty locations; high ambient
1 to 3
TYPE OF SERVICE
Table 2. Grease Manufacturers
MANUFACTURER GREASE (NLGI #2)
Shell Gadus S2 V100 2
Exxon/Mobil Ronex MP
Twin City IM-4220 5
Model DBS (Single)
2.00
H
4X 0.53
MOUNTING BRACKETS MAY
BE MOUNTED ON TOP OR
BOTTOM OF FAN
A
MODEL
DBS
080
090
100
120
140
160
180
200
A B C
16.13 18.38 23.31 10.53 15.38 13.13 20.43 20.13 1.31 1.00 145T 10.50 57
18.00 20.63 24.31 11.78 17.63 15.00 22.68 21.13 1.31 1.00 145T 11.75 65
19.69 22.25 28.31 13.12 19.25 16.69 24.31 24.88 1.31 1.00 184T 13.13 77
25.25 28.75 33.81 16.38 25.75 21.25 30.81 30.38 1.31 1.00 184T 16.38 129
27.50 32.39 34.09 18.31 28.38 23.50 34.43 30.00 1.63 1.50 184T 18.25 151
30.75 36.25 38.09 20.44 32.25 26.75 38.31 34.00 1.63 1.50 184T 20.44 180
34.88 41.00 43.09 22.88 37.00 30.88 43.06 39.00 1.63 1.63 215T 22.88 226
38.63 45.38 47.59 25.59 41.38 34.63 47.43 43.38 1.63 2.00 256T 25.63 261
D
SQ.
Notes:
1. All figures are in inches unless noted otherwise.
2. Average ship weight is for fan and motor assembly.
3. Dimensions are not to be used for construction.
G
D SQ.
1.50
B
J
K
C
E F G H J K
E
F
MAX
FRAME
DAMPER
SIZE, SQ.
AVG. SHIP
WT. (LBS.)
D-4220-1
Model DBT (Twin)
MOUNTING BRACKETS MAY
BE MOUNTED ON TOP OR
BOTTOM OF FAN
L
2X F
MODEL
DBT
080
090
100
120
140
160
180
200
A B C
17.88 36.69 23.31 10.53 15.38 13.13 38.75 20.13 7.31 18.31 1.00 145T 10.50 97
19.75 41.19 24.31 11.78 17.63 15.00 43.25 21.13 8.00 20.56 1.00 145T 11.75 115
21.44 44.50 28.31 13.12 19.25 16.69 46.50 24.88 8.63 22.19 1.00 184T 13.13 143
27.00 57.50 33.81 16.38 25.75 21.25 59.50 30.38 10.38 28.69 1.00 184T 16.38 242
29.25 64.75 34.09 18.31 28.38 23.50 66.75 30.00 11.63 32.31 1.50 184T 18.25 270
32.50 72.50 38.09 20.44 32.25 26.75 74.50 34.00 12.75 36.19 1.50 215T 20.44 322
36.63 82.00 43.09 22.88 37.00 30.88 84.00 39.00 14.06 40.94 1.63 215T 22.88 413
40.38 90.75 47.59 25.59 41.38 34.63 92.75 43.38 15.44 45.31 2.00 286T 25.63 523
Notes:
1. All figures are in inches unless noted otherwise.
2. Average ship weight is for fan and motor assembly.
3. Dimensions are not to be used for construction.
4. Damper quantity is two.
D
SQ.
E F G H J K L
2X E
K
D SQ.
J
2.00
C
4X 0.53
H
M
G
B
N
A
MAX
FRAME
DAMPER
SIZE, SQ.
AVG. SHIP
WT. (LBS.)
D-4220-2
6 Twin City IM-4220
Mounting Brackets
3.69
Models DBS and DBT can be hung from above or mounted on the floor. Typical dimensions (G and H) for the
mounting brackets that are supplied with these units are shown on page 6. The
9
⁄16" holes in these brackets can
readily be used for installing the units.
Overhead Mounting
2.15
HANGER ROD, NUTS &
WASHERS (BY INSTALLER)
HANGER BRACKET
DBS/DBT UNIT
NEOPRENE
ISOLATOR
2.72
DBS/DBT UNIT
HANGER HOUSING
BOLT, NUTS &
WASHERS (INCLUDED)
HANGER BRACKET
3.00
DBS/DBT UNIT
SPRING
ISOLATOR
5.25
Floor Mounting
DBS/DBT UNIT
3.50
FINISHED FLOOR
DBS/DBT UNIT
1.50
Twin City IM-4220 7
Limitation of Warranties and Claims
Seller warrants to the original purchaser that the goods
sold hereunder shall be free from defects in workmanship and material under normal use and service (except
in those cases where the materials are supplied by the
buyer) for a period of one year from the date of original
installation or eighteen (18) months from the date of
shipment, whichever occurs first. The liability of seller
under this warranty is limited to replacing, repairing, or
issuing credit (at cost, F.O.B. factory and at seller’s
discretion) for any part or parts which are returned by
buyer during such period provided that:
a. seller is notified in writing within ten (10) days fol-
lowing discovery of such defects by buyer, or within
ten (10) days after such defects should reasonably
have been discovered, whichever is less;
b. the defective unit is returned to seller, transportation
charges prepaid by buyer.
c. payment in full has been received by seller for said
products; and
d. seller’s examination of such unit shall disclose to its
satisfaction that such defects have not been caused
by misuse, neglect, improper installation, repair,
alteration, act of God, or accident.
No warranty made hereunder shall extend to any seller
product whose serial number is altered, effaced or
removed. Seller makes no warranty, express or implied,
with respect to motors, switches, controls, or other
components of seller’s product, where such components
are warranted separately by their respective manufacturers. THIS WARRANTY IS EXPRESSLY IN LIEU OF
ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
WHETHER STATUTORY OR OTHERWISE, INCLUDING
ANY IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE. In no event
shall seller be liable to buyer for indirect, incidental collateral, or consequential damages of any kind.
(BUYER’S FAILURE TO PAY THE FULL AMOUNT DUE
WITHIN SIXTY (60) DAYS OF DATE OF INVOICE SHALL
OPERATE TO RELEASE SELLER FROM ANY AND ALL
LIABILITY OR OBLIGATION ARISING PURSUANT TO
ANY WARRANTY, EXPRESS OR IMPLIED, WHETHER
STATUTORY OR OTHERWISE, INCLUDING ANY IMPLIED
WARRANTY OR MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE, MADE IN CONNECTION
WITH ANY CONTRACT FORMED HEREUNDER. BUYER
AGREES THAT SUCH FAILURE TO PAY SHALL
CONSTITUTE A VOLUNTARY WAIVER OF ANY AND ALL
SUCH WARRANTIES ARISING PURSUANT TO SUCH
CONTACT.)
TWIN CITY FAN & BLOWER | WWW.TCF.COM
5959 Trenton Lane N | Minneapolis, MN 55442 | Phone: 763-551-7600 | Fax: 763-551-7601
2MWG02/11
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