Greenheck RBU Installation Manual

PN 455700

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Models RBU/RBUMO/RDU

Propeller Upblast Roof Fans

Installation, Operation and Maintenance Manual

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

Installation, Operation and Maintenance Manual

information. Failure to comply with instructions could result in personal injury and/or property damage!

Propeller Upblast Roof Fans
Direct Drive and Belt Drive

Upblast propeller fans are designed to discharge
contaminants up and away from the building for most
commercial jobs and many industrial applications.
These roof exhaust fans are produced with either
belt or direct drives and with steel or aluminum
blades. Drive frames and panels are constructed
to match the level of duty and motor size.

Inspection

Fans are thoroughly inspected and test run at the
factory prior to shipment. However, damage may
occur during handling and shipping. Consequently, it is
important that the unit be carefully inspected for visible
and concealed damage before beginning installation.
Report any damage to the shipper immediately. In
addition, assure all accessory items are accounted for.

Fig. 1

Lifting Lugs

Installation

Lifting

Attach a suitable chain or strap to the four windband
mounting brackets, which are designed to be used as
lifting lugs (Fig. 1).

Do not lift the fan by the motor, belt tube, damper
frame, windband or accessories.

Carefully lift the fan to the roof curb and install fasteners
in all holes provided in the unit base. The windband
does not need to be removed for the lifting operation.

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Propeller Upblast Roof Fans

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Electrical Connections

Before electrical connections are made, the supply

For Models RBUMO with high
temperature option - UL Listed

voltage, phase and ampere capacity must be checked
for compatibility with the fan motor. In addition, the
supply wiring must be properly fused and conform to
local and national electrical codes.

The supply wires are then connected to an optional
safety disconnect switch (if ordered) or wired directly
to the motor.

For belt drive units in Emergency Smoke Removal
installations, the electrical supply must be kept out of

the airstream. They may also require an isolated power
supply so that if power is cut to the building in the
event of a fire, the fan will continue to operate. Check
the local and national electrical codes for emergency
smoke removal fans.

Listed
Power
Ventilator
For Smoke
Control
Systems
76Y9

Models RBUMO with High Temperature Option, UL Listed
will bear the label shown above. For fan sizes 42, 48, 54 and
60 Figs. 2A and 2B apply (pg. 3)

ELECTRICAL - If fan motor is NOT thermally
protected, remote overload protection must
be installed having adequate rating as to
voltage, frequency, horsepower, and full
load current per phase. Where connected to
a circuit protected by fuses, use time delay
fuses. For supply connection use wires rated
for at least 90ºC (194ºF).

INSTALLATION - When connecting electrical
power to this fan, do not restrict motor
movement. Motor must have sufficient
movement for possible future belt or wheel
adjustment. 454975

Disconnect Wiring Options Note: Conduit and wiring by others

IMPORTANT

Disconnect Installation

RBU with NEMA-3R

Typical Installation

Wire on
inside of unit

Not recommended for high temperature exhaust

Disconnect Installation

RBUMO with NEMA-3R

High Temperature Installation

Wire on
outside of unit

Disconnect Installation

RBUMO with NEMA-3R

RBU on a GPI Curb with NEMA-3R

Propeller Upblast Roof Fans

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RBUMO with GPI and NEMA-3R

No Tray

RBUMO with GPI and NEMA-3R

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WARNING!

Disconnect and secure to the “off” position all
electrical power to the fan prior to inspection or
service.

Caution must be used when working around the
fusible link damper lifters. They may release the
dampers unexpectedly.

Models RBU, RBUMO and RDU may have fusible
link damper lifters and all RBUMO models with high
temperature options have fusible link damper lifters
under spring tension. RBUMO fans UL listed as
“Power Ventilators For Smoke Control Systems” in
sizes 42, 48, 54 and 60 have extra heavy duty fusible
link damper lifters under high spring tension that, for
safety reasons, must be pinned to prevent accidental
release. See Fig. 2 below for details on how to secure
the lifter arms.

FAILURE TO COMPLY WITH THESE SAFETY

PRECAUTIONS MAY RESULT IN SERIOUS

INJURY OR DEATH!

WARNING!

These fans have extra heavy duty fusible link damper
lifters under very high spring tension that must be
pinned so they can not be accidentally tripped when
servicing the fan. The fusible link damper lifters are
located under the butterfly damper blades. Fig. 3.
Fig. 2A shows where the two safety pins will be
located when shipped from the factory.

When maintenance is being performed on the fan, the
pins MUST be moved from Fig. 2A position to Fig. 2B
position. Fig. 2A shows where the two safety pins are
placed when the fan is in service.

Fan sizes 20, 24, 30 and 36 do not have the ability
to be pinned when servicing due to differences in
lifter designs.

IN ALL CASES, EXTREME CARE MUST BE TAKEN

WHEN WORKING AROUND THE DAMPER LIFTER

ASSEMBLIES OR SERIOUS BODILY INJURY

OR DEATH MAY RESULT.

Fig. 2

Safety Pin
Storage Location

Fig. 2A

To Prevent Closure
While Servicing Fan

Fig. 2B

Prestarting Checks

Check all fasteners and set screws for tightness.
This is especially important for bearing set screws.

The propeller should rotate freely and not rub on the fan
panel venturi. Rotation direction of the propeller should
be checked by momentarily turning the unit on. Rotation
should be in the same direction as the rotation decal
affixed to the unit or as shown in Fig. 4. For 3-phase
installations, fan rotation can be reversed by simply
interchanging any two of the three electrical leads. For
single phase installations, follow the wiring diagram
located on the motor.

Fig. 3

Butterfly
Damper
Blades

Rotation

Fig. 4

For Belt Drive Fans

The adjustable motor pulley is preset at the factory for
the specified fan RPM. Fan speed can be increased
by closing or decreased by opening the adjustable
pulley. Two or three groove variable pitch pulleys
must be adjusted an equal number of turns open. Any
increase in fan speed represents a substantial increase
in horsepower required from the motor. Always check
motor load amperage and compare to name plate
rating when changing fan speed.

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Propeller Upblast Roof Fans

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Routine Maintenance

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WARNINg

Disconnect and Secure to the “OFF” position all

electrical power to the fan prior to inspection or

servicing. Failure to comply with this safety

precaution could result in serious injury or death.

Once the fan has been put into operation, a periodic
maintenance program should be set up to preserve
the reliability and performance of the fan. Items to be
included in this program are:

• Belts • Bearings • Fasteners • Set Screws

• Lubrication • Removal of Dust/Dirt

Belts

Premature belt failures are frequently caused by
improper belt tension (either too tight or too loose) or
misaligned pulleys. The proper tension for operating a
V-belt is the lowest tension at which the belts will not
slip at peak load conditions. For initial tensioning, the
proper belt deflection half way between pulley centers
is 1/64 inch for
each inch of belt
span. For example,
if the belt span is
64 inches, the belt

Deflection =

deflection should
be one inch using
moderate thumb
pressure at midpoint
of the drive (Fig. 5).

Fig. 5

Check belt tension two times during the first 24 hours
of operation and periodically thereafter. To adjust belt
tension, simply loosen four fasteners (two on each side
of the motor plate) and slide the motor plate away from
the fan shaft until proper belt tension is attained. On
some fans, fasteners attaching the motor to the motor
plate must be loosened in order
to adjust the belt.

It is very important that the drive
pulleys remain in proper alignment
after adjustments are made.
Misalignment of pulleys will result
in premature belt wear, noise,
vibration and power loss. (Fig. 6).

Fig. 6

WRONG

WRONG

Belt Span

64

CORRECT

WRONG

Belt
Span

Bearings (For belt drive fans only)

Bearings are the most critical moving part of the fan
and should be inspected at periodic intervals. Locking
collars, set screws and fasteners attaching the bearings
to the bearing plate, must be checked for tightness. In a
clean environment and temperatures above 32ºF/below
200ºF, fan shaft bearings with grease fittings should be
lubricated semi-annually using a high quality lithium
based grease. If unusual environmental conditions exist,
temperatures below 32ºF/above 200ºF, moisture or
contaminants, more frequent lubrication is required.

With the unit running, add grease very slowly with a
manual grease gun until a slight bead of grease forms
at the seal. Be careful not to unseat the seal by over
lubricating or using excessive pressure. Bearings
without grease fittings are lubricated for life.

Fasteners and Set Screws

Any fan vibration has a tendency to loosen mechanical
fasteners. A periodic inspection should include checking
all fasteners and set screws for tightness. Particular
attention should be paid to set screws attaching the
propeller to the shaft and the shaft to the bearings.
Loose bearing set screws will lead to premature failure
of the fan shaft.

Lubrication

Refer to the paragraph on bearings for bearing
lubrication. Many fractional horsepower motors installed
on the smaller fans are lubricated for life and require
no further attention. Motors equipped with oil holes
should be oiled in accordance with the manufacturer’s
instructions printed on the motor. Use a high grade SAE
20 machine oil and use caution not to over lubricate.
Motors supplied with grease fittings should be greased
according to directions printed on the motor.

Removal of Dust and Dirt

Dirt clogs cooling openings on the motor housing,
contaminates bearing lubricant, and collects on
propeller blades causing severe imbalance if left
unchecked. The exterior surface of the motor, fan panel
and entire propeller should be thoroughly cleaned
periodically. Use caution and do not allow water or
solvents to enter the motor or bearings. Under no
circumstances should motors or bearings be sprayed
with steam or water.

Damper Inspection and Service

CAUTION: Butterfly dampers on units supplied
with optional spring lifter bars are under spring
tension and will open forcefully if the fusible link is
released. Butterfly dampers should be inspected
for proper operation at each service interval.
Check for freedom of movement and general
condition of the damper blades and hinge rods.

Propeller Upblast Roof Fans

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Service Access

Model RBUMO - Motor Out of Airstream

Model RBUMO simplifies inspection and servicing with
the “motor out of the airstream” design. A removable
motor cover enables quick and easy access to the
motor, belt, and drives for replacement or adjustment
from the roof deck.

Removable
Windband

Removable Windband

The windband can be removed by removing the bolts
from the four windband mounting brackets. With the
windband removed, access to the fan can be gained
through the butterfly dampers. This service feature
applies to models RBU, RBUMO and RDU.

Butterfly
Damper
Blades

Removable
Motor Cover

Servicing of propeller and bearings can also be
accomplished by removing the fan panel/windband
assembly from the fan base.

Models RBU & RDU - Motor In Airstream

To service motor, grease bearings, adjust tension and
replace belts. Models RBU and RDU motors and drives
can be accessed from below the fan. If the fan was
ordered with an inlet guard, all service will need to be
completed from above the fan.

Follow the instructions for:

• Removable Windband

• Prop Removal

• Adjust Tension - Remove Motor

IMPORTANT

To service the fan it is recommended the fan be
accessed from below (looking up). If this is not
possible, or the fan is equipped with inlet guards,
the fan may be serviced from above by taking off
the removable windband.

Option A

Remove bolts (8)
that fasten the entire
windband/damper
assembly to the fan

Option B

Remove bolts (8)
that fasten the lifting
lungs - this will allow
the outer windband to
be removed. Next the
damper assembly will
need to be removed.

For fans equipped with damper lifters

refer to warning on Page 3.

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Propeller Upblast Roof Fans

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Prop Removal

(Image 1 and 2)

Loosen the set screw located on the side of the
bushing. Remove the 3 top bolts on the bushing that
fasten to the prop. Insert 2 of these bolts into the two
threaded holes on the busing to separate the bushing
and the wheel. Make sure the prop is supported so that
it is not damaged on the support angles. May need to
use a gear puller to assist in this process.

Image 1

Image 2

Image 3: Loosen bolts - adjust motor plate

Adjust Tension - Remove Motor

(Images 3, 4 and 5)

Once the prop is removed you can gain access
to the motor and drives. There are 4 bolts on
the motor plate that need to be loosened to
allow the belt tension to be adjusted.

For motor removal, it is recommended that you
remove the motor plate and motor at the same
time. Large motors will require a lift to secure
the motor while removing the fasteners and to
lift the motor plate assembly out of the unit

Propeller Upblast Roof Fans

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Image 4: Adjust motor plate

Image 5: Adjust belt tension

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Parts List

RBU Parts List

9

3

1

2

RBUMO Parts List

9

5

4

6

11

10

10

RDU Parts List

8

4

5

4

67

8

1

2

7

3

1

2

5

3

1. Fan Panel

2. Propeller

3. Drive Frame Channel (2)

4. Motor Plate

5. Motor

6. Motor Pulley

7. Shaft Pulley

8. Fan Shaft

9. Bearings (2)

10. Belt

11. Motor Cover (RBUMO only)

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Propeller Upblast Roof Fans

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Warranty

Greenheck warrants this equipment to be free from defects in material and workmanship for a period of one year from the
shipment date. Any units or parts which prove to be defective during the warranty period will be replaced at our option
when returned to our factory, transportation prepaid. Motors are warranted by the motor manufacturer for a period of one
year. Should motors furnished by Greenheck prove defective during this period, they should be returned to the nearest
authorized motor service station. Greenheck will not be responsible for any removal or installation costs.

As a result of our commitment to continuous improvement, Greenheck reserves the right to change specifications without notice.

Greenheck Propeller Upblast Roof Fans catalog provides
additional information describing the equipment, fan perfor­mance, available accessories, and specification data.

AMCA Publication 410-96, Safety Practices for Users and
Installers of Industrial and Commercial Fans, provides
additional safety information. This publication can be
obtained from AMCA International, Inc. at www.amca.org.

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Phone: [phone] • Fax: [phone] • E-mail: [e-mail] • Website: www.greenheck.com

455700 • RBU/RBUMO/RDU, Rev. 5, September 2011 Copyright 2011 © Greenheck Fan Corporation

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