Please read and save these instructions for future reference. Read carefully before attempting to assemble,
install, operate or maintain the product described. Protect yourself and others by observing all safety
information. Failure to comply with instructions could result in personal injury and/or property damage!
Model XRED
Direct Drive
Model XRED is a direct drive
downblast centrifugal exhaust
fan. These fans are specifically
designed for roof mounted
applications exhausting relatively
clean air. Performance capabilities
range up to 4,300 cfm (7,305 m
and up to 1 in. wg (249 Pa) of
static pressure. The maximum
continuous operating temperature
is 180°F (82ºC). XRED models are
available in 27 sizes with nominal
wheel diameter ranging from 8 to
24 inches (203 to 610 mm) (060 - 243 unit sizes). Each
fan shall bear a permanently affixed manufacturer’s
engraved metal nameplate containing the model
number and individual serial number. All fans are UL/
cUL Listed Standard 705.
3
/hr)
General Safety Information
Only qualified personnel should install this fan.
Personnel should have a clear understanding of these
instructions and should be aware of general safety
precautions. Improper installation can result in electric
shock, possible injury due to coming in contact with
moving parts, as well as other potential hazards. Other
considerations may be required if high winds or seismic
activity are present. If more information is needed,
contact a licensed professional engineer before moving
forward.
DANGER
Always disconnect, lock and tag power source before
installing or servicing. Failure to disconnect power
source can result in fire, shock or serious injury.
CAUTION
When servicing the fan, motor may be hot enough
to cause pain or injury. Allow motor to cool before
servicing.
CAUTION
Precaution should be taken in explosive atmospheres.
Model XREB
Belt Drive
XREB model fans are belt drive
downblast centrifugal exhaust fans.
These fans are specifically designed
for roof mounted applications
exhausting relatively clean air.
Performance capabilities range
up to 44,700 cfm (75,950 m
and up to 2.5 in. wg (623 Pa) of
static pressure. The maximum
continuous operating temperature
is 180°F (82ºC). XREB models
are available in twenty sizes with
nominal wheel diameters ranging
from 11 to 54 inches (279 to 1372 mm) (071-540
unit sizes). Each fan shall bear a permanently affixed
manufacturer’s nameplate containing the model
number and individual serial number. All fans are
UL/cUL Listed Standard 705.
1. Follow all local electrical and safety codes, as
well as the National Electrical Code (NEC) and the
National Fire Protection Agency (NFPA), where
applicable. Follow the Canadian Electrical Code
(CEC) in Canada.
2. The rotation of the wheel is critical. It must be free
to rotate without striking or rubbing any stationary
objects.
3. Motor must be securely and adequately grounded.
4. Do not spin fan wheel faster than max cataloged
fan RPM. Adjustments to fan speed significantly
affects motor load. If the fan RPM is changed, the
motor current should be checked to make sure it is
not exceeding the motor nameplate amps.
5. Do not allow the power cable to kink or come in
contact with oil, grease, hot surfaces or chemicals.
Replace cord immediately if damaged.
6. Verify that the power source is compatible with the
equipment.
7. Never open access doors to a duct while the fan is
running.
3
/hr)
Downblast Centrifugal Roof Exhaust Fans
1
Page 2
Receiving
Upon receiving the product, check to make sure all
items are accounted for by referencing the bill of lading
to ensure all items were received. Inspect each crate for
shipping damage before accepting delivery. Notify the
carrier if any damage is noticed. The carrier will make
notification on the delivery receipt acknowledging any
damage to the product. All damage should be noted on
all the copies of the bill of lading which is countersigned
by the delivering carrier. A Carrier Inspection Report
should be filled out by the carrier upon arrival and
reported to the Traffic Department. If damaged upon
arrival, file a claim with carrier. Any physical damage
to the unit after acceptance is not the responsibility of
Larkin Industries, Inc.
Unpacking
Verify that all required parts and the correct quantity
of each item have been received. If any items are
missing, report shortages to your local representative to
arrange for obtaining missing parts. Sometimes it is not
possible that all items for the unit be shipped together
due to availability of transportation and truck space.
Confirmation of shipment(s) must be limited to only
items on the bill of lading.
Handling
XRED Direct Drive
Lift unit on to the roof utilizing hooks under the lip of
the shroud. Evenly space the hooks around the shroud
using a minimum of four lifting straps. Use a spreader
bar to ensure the straps do not come in contact with the
unit (see Figure 1).
Figure 1
Spreader Bar
Lifting Strap
Hook
Figure 2
Hook With
Safety Latch
(Supplied by others)
(2) Bearing Plate
Lifting Points
(4) Drive Frame
Lifting Points
Figure 3
Screws
Curb Cap
Screws
1¾ in.
(44 mm)
XREB Belt Drive
When lifting the unit on to the roof, use either the four
lifting points on the drive frame or the two lifting points
on the bearing plate if present (see Figure 2 for lifting
points). Access to the drive frame is accomplished by
removing the screws pointed out in Figure 3. The cover
can then be removed and placed on a flat surface in an
area protected from strong winds.
When XRED/XREB unit is on the roof, move fan to
desired location using lifting points and fasten securely
through mounting holes in base. Shims may be
necessary depending upon roofing material thickness.
The motor amperage and voltage ratings must be
checked for compatibility to supply voltage prior to final
electrical connection. For XRED/XREB installations, the
electrical supply should be routed through the conduit
chase located between the curb cap and the bottom of
the motor compartment. Wiring must conform to local
and national codes.
Downblast Centrifugal Roof Exhaust Fans
2
Page 3
Storage
Fans are protected against damage during shipment. If
the unit cannot be installed and operated immediately,
precautions need to be taken to prevent deterioration of
the unit during storage. The user assumes responsibility
of the fan and accessories while in storage. The
manufacturer will not be responsible for damage during
storage. These suggestions are provided solely as a
convenience to the user.
Indoor
The ideal environment for the storage of fans and
accessories is indoors, above grade, in a low humidity
atmosphere which is sealed to prevent the entry of
blowing dust, rain or snow. Temperatures should be
evenly maintained between 30° to 110°F (-1° to 43°C)
(wide temperature swings may cause condensation
and “sweating” of metal parts). All accessories must be
stored indoors in a clean, dry atmosphere.
Remove any accumulations of dirt, water, ice or snow
and wipe dry before moving to indoor storage. To avoid
“sweating” of metal parts, allow cold parts to reach
room temperature. To dry parts and packages, use
a portable electric heater to get rid of any moisture
buildup. Leave coverings loose to permit air circulation
and to allow for periodic inspection.
The unit should be stored at least 3½ inches (89 mm)
off the floor on wooden blocks covered with moisture
proof paper or polyethylene sheathing. Aisles between
parts and along all walls should be provided to permit
air circulation and space for inspection.
Inspection and Maintenance during
Storage
While in storage, inspect fans once per month. Keep a
record of inspection and maintenance performed.
If moisture or dirt accumulations are found on parts,
the source should be located and eliminated. At each
inspection, rotate the wheel by hand ten to fifteen
revolutions to distribute lubricant on motor. If paint
deterioration begins, consideration should be given to
touch-up or repainting. Fans with special coatings may
require special techniques for touch-up or repair.
Machined parts coated with rust preventive should be
restored to good condition promptly if signs of rust
occur. Immediately remove the original rust preventive
coating with petroleum solvent and clean with lint-free
cloths. Polish any remaining rust from surface with
crocus cloth or fine emery paper and oil. Do not destroy
the continuity of the surfaces. Thoroughly wipe clean
with Tectyl
hard to reach internal surfaces or for occasional use,
consider using Tectyl
or the equivalent.
®
506 (Ashland Inc.) or the equivalent. For
®
511M Rust Preventive, WD-40®
Removing From Storage
As fans are removed from storage to be installed in their
final location, they should be protected and maintained
in a similar fashion until the fan equipment goes into
operation.
Outdoor
Fans designed for outdoor applications may be stored
outdoors, if absolutely necessary. Roads or aisles for
portable cranes and hauling equipment are needed.
The fan should be placed on a level surface to prevent
water from leaking into the fan. The fan should be
elevated on an adequate number of wooden blocks so
that it is above water and snow levels and has enough
blocking to prevent it from settling into soft ground.
Locate parts far enough apart to permit air circulation,
sunlight and space for periodic inspection. To minimize
water accumulation, place all fan parts on blocking
supports so that rain water will run off.
Do not cover parts with plastic film or tarps as these
cause condensation of moisture from the air passing
through heating and cooling cycles.
Fan wheels should be blocked to prevent spinning
caused by strong winds.
Downblast Centrifugal Roof Exhaust Fans
3
Page 4
WARNING
Installation, troubleshooting and parts replacement is
to be performed only by qualified personnel.
WARNING
Disconnect power before installing or servicing.
CAUTION
A fan manufactured with an explosion resistant motor
does not certify the entire unit to be explosion proof.
Installation
Typical Roof Mounting Installation
1. On the roof surface, cut an appropriate sized hole
and follow manufacturer’s instructions on curb
installation. Caulk and flash the curb to ensure a
water tight seal.
2. If unit is equipped with a backdraft damper, it
should be installed now.
3. Remove motor cover. Access to the motor
compartment is accomplished by removing the
screws as shown in Figure 3.
4. Only on XREB Belt Drive fans. On the drive frame
use the lifting lugs to lift and place the unit on top of
roof curb. (Refer to Figure 2 on page 2).
5. Secure fan to curb using a minimum of eight lag
screws, metal screws or the suitable fasteners.
Shims may be required depending upon curb
installation and roofing material.
Note: Severe duty applications may require
additional fasteners.
6. Verify power line wiring is de-energized before
connecting fan motor to power source.
7. Connect power supply wiring to the motor as
indicated on the motor nameplate or terminal box
cover. Check the power source for compatibility
with the requirements of your equipment.
8. Check fan wheel for free rotation, recenter if
necessary.
9. Check all fasteners for tightness.
10. Mount and wire safety disconnect switch under
motor cover. Wire control switches at ground level,
refer to Figure 4.
11. Replace motor cover.
Downblast Centrifugal Roof Exhaust Fans
4
Typical Wiring Diagram
MOTOR
SUPPLY VOLTAGE
115/208-230/60/1
J-BOX
Figure 4
L1
L2
Vari-Green Wiring
Contact Larkin Industries for Vari-Green motor wiring
* Approximate weight shown in pounds (kilograms) is the largest
cataloged Open Drip Proof motor.
• The roof curb should be 1½ in. (38 mm) less than the curb cap to allow
for roofing and flashing.
Downblast Centrifugal Roof Exhaust Fans
5
Page 6
Pre-Starting Checks
1. Check all fasteners and set screws for tightness.
The wheel should rotate freely and be aligned as
shown in Figure 7 below.
2. Wheel position is preset and the unit is test run at
the factory. Movement may occur during shipment
and realignment may be necessary.
3. Only XRED unit - Centering height alignment can
be accomplished by loosening the set screws in
the wheel and moving the wheel to the desired
position.
4. Only XREB unit - Centering can be accomplished
by loosening the bolts holding the drive frame
to the shock mounts and repositioning the drive
frame.
5. Only XREB unit - Wheel and inlet cone overlap
can be adjusted by loosening the set screws in
the wheel and moving the wheel to the desired
position.
6. Only XREB unit - Fan RPM should be checked and
verified with a tachometer.
7. Check wheel rotation (viewing from the shaft side)
by momentarily energizing the unit. Rotation should
be clockwise as shown in Figure 8 and correspond
to rotation decal on the unit. If wheel rotation is
incorrect, reverse two of the wiring leads or check
motor wiring for single phase.
Wheel Overlap and Gap Dimensions
Model
XRED060-095–3/32 (2)
XRED97-1631/4 (6)–
XREB071-1611/4 (6)–
XRED183-2433/8 (10)–
XREB180-2403/8 (10)–
XREB260-5401/2 (13)–
G - Overlap
in. (mm)
H - Gap
in. (mm)
Wheel Rotation
Clockwise
Rotation
All Models
Figure 8
WARNING
Correct direction of wheel rotation is critical. Reversed
rotation will result in poor air performance, motor
overloading and possible burnout.
WARNING
The fan has been checked for mechanical noises at
the factory prior to shipment. If mechanical noise
should develop, suggested corrective actions are
offered in the Troubleshooting section.
IMPORTANT
Over tightening will cause excessive bearing wear and
noise. Too little tension will cause slippage at startup
and uneven wear.
Model XREB
Pre-Starting Belt Tension Checks
8. Always loosen tension enough to install belts
without stretching, see Figure 9.
Belts
Do not force belt(s). Forcing the belt(s)
Figure 9
will break the cords and cause belt failure.
G
Figure 7
Downblast Centrifugal Roof Exhaust Fans
6
9. For units with two groove pulleys, adjust so the
tension is equal in both belts.
H
10. If adjustments are made, it is very important to
check the pulleys for proper alignment. Misaligned
pulleys lead to excessive belt wear vibration, noise
and power loss, see Figure 10.
Figure 10
Page 7
Fasteners
(4) four fasteners*
*Identical fasteners on
opposing side must also
be loosened.
Figure 11
11. Belt tension can be adjusted by loosening four
fasteners on the drive frame, see Figure 11. The
motor plate slides on the slotted adjusting arms and
drive frame angles in the same manner.
12a. Sizes 071-161: Belts should be tensioned just
enough to prevent slippage at full load.
Note: Belts should have a slight bow on the slack
side while running at full load (see Figure 12a).
Deflection
Slack
Side
Figure 12a Figure 12b
12b. Sizes 180-540: Belt tension should be adjusted to
allow 1/64 in. (0.397 mm) of deflection per inch of
belt span. For example, a 15 in. (381 mm) belt span
should have 15/64 in. (0.234 mm) (or about 1/4 in.
(6 mm)) of deflection with moderate thumb pressure
at mid-point between pulleys (see Figure 12b).
13. The adjustable motor pulley is factory set for the
RPM specified. Speed can be increased by closing
or decreased by opening the adjustable motor pulley.
14. Any increase in speed represents a substantial
increase in the horsepower required by the unit.
15. Motor amperage should always be checked to avoid
serious damage to the motor when speed is varied.
Operation: XRED / XREB
1. Before starting up or operating fan, check all
fasteners for tightness. In particular, check the
setscrews in wheel hub.
2. While in the OFF position or before connecting the
fan to power, turn the fan wheel by hand to be sure
it is not striking the venturi or any obstacle.
3. Start the fan and shut it off immediately to check
rotation of the wheel with directional arrow in the
motor compartment.
4. When the fan is started, observe the operation and
check for any unusual noises.
5. With the system in full operation and all ductwork
attached, measure current input to the motor and
compare with the nameplate rating to determine if
the motor is operating under safe load conditions.
6. Keep inlets and approaches to fan clean and free
from obstruction.
IMPORTANT
Adjust (tighten) belt tension after the first 24-48 hours
of operation.
Inspection
Inspection of the fan should be conducted at the
first 30 minute and 24 hour intervals of satisfactory
operation.
30 Minute Interval
Inspect bolts, setscrews and motor mounting bolts.
Adjust and tighten as necessary.
24 Hour Interval
Check all internal components. On XREB unit only,
inspect belt alignment and tension. Adjust and tighten
as necessary.
Maintenance: XRED / XREB
Installation and maintenance are to be performed only
by qualified personnel who are familiar with local codes
and regulations and who are experienced with this type
of equipment.
Motor maintenance is generally limited to cleaning
and lubrication (where applicable). Cleaning should be
limited to exterior surfaces only. Removing dust buildup
on motor housing ensures proper motor cooling.
WARNING
Always disconnect, lock and tag power source before
servicing. Failure to disconnect power source can
result in fire, shock or serious injury.
Greasing of motors is only intended when fittings are
provided. Many fractional horsepower motors are
permanently lubricated and should not be lubricated
after installation. Motors supplied with grease fittings
should be greased in accordance with manufacturers’
recommendations. Where motor temperatures do not
exceed 104ºF (40ºC), the grease should be replaced
after 2,000 hours of running time as a general rule.
Wheels require very little attention when moving clean
air. Occasionally, oil and dust may accumulate causing
imbalance. When this occurs, the wheel and housing
should be cleaned to ensure smooth and safe operation.
All fasteners should be checked for tightness each time
maintenance checks are performed prior to restarting
unit.
A proper maintenance program will help these units
deliver years of dependable service.
CAUTION
Uneven cleaning of the wheel will produce an out of
balance condition that will cause vibration in the fan.
WARNING
This unit should be made non-functional when
cleaning the wheel or housing (fuses removed,
disconnect locked off).
Downblast Centrifugal Roof Exhaust Fans
7
Page 8
Belt/Bearing Maintenance XREB Unit
1. Belts tend to stretch after a period of time. They
should be checked periodically for wear and
tightness. When replacing belts, use the same type
as supplied with the unit.
2. Matched belts should always be used on units with
multi-groove pulleys.
3. For belt replacement, loosen the tensioning device
enough to allow removal of the belt by hand.
4. Once installed, adjust belts as shown in
“Pre-Starting Checks.”
5. Shaft bearings can be classified in two
groups: relubricating and non-relubricating. All
non-relubricating bearings on model XREB fans are
factory lubricated and require no further lubrication
under normal use (between -20º to 180ºF (-29º to 82ºC) in a relatively clean environment).
6. On XREB belt driven fans, the standard cast
pillow block bearings are factory lubricated and
are provided with external grease fittings. Annual
lubrication is recommended, or more frequently
if needed (See Table 2). Do not over-grease. Use
only one or two shots of lubricant with a hand
gun. Maximum hand gun rating is 40 psi. Rotate
bearings during lubrication where good safety
practice permits. Caution should be employed to
prevent over packing or contamination.
7. Grease fittings should be wiped clean. The unit
should be in operation while lubricating. Extreme
care should be used around moving parts.
8. Grease should be pumped in very slowly until a
slight bead forms around the seal. A high grade
lithium base grease should be used. (See Table 3)
9. To ensure tightness, check pulley setscrews. Proper
keys must be in keyways.
10. Fan RPM should not be readjusted. Only use
pulleys of identical size and type when replacing
pulleys.
11. During the first few months of operation, check
bearing setscrews periodically to ensure tightness.
12. If unit is to be left idle for an extended period,
remove belts and store in a cool, dry place to avoid
premature belt failure.
Recommended Relubrication
Frequency in Months
NOTE: If unusual environment conditions exist (extreme
temperature, moisture or contaminants) more frequent
lubrication is required.
A good quality lithium base grease, conforming to NLGI
Grade 2 consistency, such as those listed here may be
used.
Table 2: Suggested Fan Bearing Greasing Intervals
Interval
(months)
1 to 3
3 to 6
6 to 12
12 to 18Infrequent operation or light duty in clean atmosphere
Manufacturer Grease (NLGI #2)
U.S. Electric MotorsGrease No. 83343
Chevron U.S.A. IncChevron SRI Grease #2
Mobil Oil Corporation
Texaco, Inc.
Amoco Oil Co.Rykon Premium #2
ExxonUnirex N2
ShellB Shell Alvania #2
Heavy duty in dirty, dusty locations; high ambient
temperatures; moisture laden atmosphere; vibration.
12 to 24 hours per day, heavy duty, or if moisture is
present
8 to 16 hours per day in clean, relatively dry
atmosphere
Table 3: Grease Manufacturers
Type of Service
Mobilith
Mobil 532
Premium BRB #2
Texaco Multifak #2
Fan Inlet Connections
In order to assure proper fan performance, caution must be exercised in fan placement and connection to the ventilation
system. Obstructions, transitions, poorly designed elbows, improperly selected dampers, etc. can cause reduced
performance, excessive noise and increased mechanical stress. For performance to be as published, the system must
provide uniform and stable airflow into the fan.
Good
Poor
Dampers must open fully.
Use motorized dampers in
low airflow applications to
reduce losses.
Downblast Centrifugal Roof Exhaust Fans
8
Avoid sharp turns or
entrance conditions which
cause uneven flow. Use
turning vanes in elbows to
reduce adverse effects.
Poor
Good
Provide uniform airflow
at fan inlet to assure
optimum performance.
Provide uniform airflow at fan inlet and through
the damper to assure optimum performance.
The curb cap should be three wheel diameters
from the radius. Use turning vanes in duct when
possible.
Page 9
Troubleshooting
WARNING: Before taking any corrective action, make certain unit is not capable of operation during repairs.
PROBLEMCAUSECORRECTIVE ACTION
Adjust wheel and/or inlet cone. Tighten wheel hub or bearing
collars on shaft.
Tighten pulleys on motor/fan shaft. Adjust belt tension. Align
pulleys properly, see page 6, Figure 9-10. Replace worn belts or
pulleys.
Replace defective bearing(s). Lubricate bearings. Tighten collars
and fasteners.
Clean all dirt off wheel. Check wheel balance, rebalance in place if
necessary.
Center wheel on inlet, see page 6, Figure 7.
Remove objects, check for damage or unbalance.
Replace motor with same frame size, RPM-HP.
Resize ductwork. Check proper operation of face and bypass
dampers. Check filters and access doors.
Check fuses/circuit breakers. Check for switches off. Check for
correct supply voltage.
Assure motor is correct horsepower and not tripping overload
protector.
Replace damaged bearing. Relieve excessive belt tension. Align
bearings. Check for bent shaft.
Check motor wiring (page 4) verify motor is wired for correct
rotation.
Check drives or slow down fan by opening variable pitch pulley on
motor shaft.
Check system: Proper operation of backdraft or control dampers,
obstruction in ductwork, clean dirty filters.
Center wheel on inlets, see Pre-Starting checks on page 6,
Figure 7.
Excessive noise
or vibration
High
horsepower
Fan does
not operate
Motor
overloads
or overheats
Reduced airflow
Wheel rubbing inlet
V-belt drive
Bearings
Wheel unbalance
Belts too tight or too looseAdjust tension, see page 7, Figure 12a-b.
Wheel improperly aligned and
rubbing
Loose drive or motor pulleysAlign and tighten. See “Pre-Starting Checks”, see page 6.
Foreign objects in wheel or
housing
Fan base not securely anchoredSecure properly.
Motor hood loose and rattlingTighten screws securing motor hood.
Defective or loose motor
bearings
FanCheck rotation of wheel, see page 6, Figure 8. Reduce fan speed.
Duct system
Electrical supply
DriveCheck for broken belts. Tighten loose pulleys.
Motor
LubricationCheck for excessive or insufficient grease in the bearing.
Mechanical
Belt slippageAdjust tension or replace bad belts, see page 6-7.
Over/Under line voltageContact power company.
Incorrect wheel rotation
Wheel RPM too high
Undersized motorCheck motor ratings with catalog speed and air capacity chart.
Motor wired incorrectlyCheck motor wiring to wiring diagram located on fan motor.
System resistance too high
Unit running backwardsCorrect as shown on page 6, Figure 8.
Excessive dirt buildup on wheels Clean wheel.
Improper wheel alignment
Dampers closedInspect and repair.
Blocked duct/clogged filterClean or replace.
Belt slippage Replace and adjust tension.
Speed too slowCheck for correct drives.
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9
Page 10
Maintenance Documentation
Job Information
Job Name: ____________________________________ Service Organization: __________________________________
NOTE: Each fan bears a manufacturer’s
nameplate with model number and serial
number embossed. This information
will assist the local representative and
the factory in providing service and
replacement parts. Before taking any
corrective action, make certain unit is not
capable of operation during repairs.
XRED Direct Drive Centrifugal Roof Exhaust Fan
Motor Cover
Motor
Shock
Mounts
Shroud
Birdguard
Wheel
Curb Cap/
Venturi
Hood Clip
Shroud Brace
Vertical
Support
Lower
Windband
XREB Belt Drive Centrifugal Roof Exhaust Fan
Motor Cover
Shaft Pulley
Bearings
Drive Frame
Assembly
Shock Mounts
Shroud
Wheel
Conduit
Chase
Vertical
Support
Belt
Motor Pulley
Motor
Fan Shaft
Birdguard
Shroud Brace
Windband
Curb Cap/
Venturi
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11
Page 12
Roof Curb Installation
Larkin Industries, Inc.
114 David Green Rd., Birmingham, AL 35244
Phone: 1.800.322.4036 Fax: 1.205.987.0583
Email: Sales@larkinhoods.com