Part #470654
VSU Make-Up Air Unit
®
with Direct-Fired Gas Heater
Installation, Operation and Maintenance Manual
Please read and save these instructions. 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! Retain instructions for future reference.
Model VSU
3. Motor must be securely and adequately grounded.
4. Do not spin fan wheel faster than the maximum
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 blower access doors while the fan is
running.
DANGER
Always disconnect power before working on or near a
unit. Lock and tag the disconnect switch or breaker to
prevent accidental power up.
CAUTION
When servicing the unit, motor may be hot enough
to cause pain or injury. Allow motor to cool before
servicing.
General Safety Information
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Do not touch electrical switches.
3. Extinguish any open flame.
4. Immediately call your gas supplier.
Only qualified personnel should install this unit.
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.
FOR YOUR SAFETY
The use and storage of gasoline or other flammable
vapors and liquids in open containers in the vicinity
of this appliance is hazardous.
1. Follow all local electrical and safety codes, as well
as the National Electrical Code (NEC), the National
Fire Protection Agency (NFPA), where applicable.
Follow the Canadian Electric Code (CEC) in
Canada.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage,
injury or death. Read the installation, operating
and maintenance instructions thoroughly before
installing or servicing this equipment.
2. The rotation of the wheel is critical. It must be free
to rotate without striking or rubbing any stationary
objects.
Model VSU Make-Up Air Unit
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1
Table of Contents
General Safety Information . . . . . . . . . . . . . . . . . . . .1
Receiving, Handling and Storage . . . . . . . . . . . . . . .2
Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Subassembly Overview:
Filter Section / Vertical Mounting Stand . . . . . . . . . .4
Optional Service Platform . . . . . . . . . . . . . . . . . . . . .4
Burner, Blower and Control Center Overview . . . . . .5
Burner Subassembly . . . . . . . . . . . . . . . . . . . . . . .6
Control Center . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Dampers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Installation
Concrete Slab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Service and Access Clearance . . . . . . . . . . . . . . . . .7
Clearance to Combustibles . . . . . . . . . . . . . . . . . . . .7
Burner/Blower Section. . . . . . . . . . . . . . . . . . . . . . . .7
Install Ductwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Complete Installation . . . . . . . . . . . . . . . . . . . . . . . . .8
Optional Service Platform. . . . . . . . . . . . . . . . . . 8-9
Electrical Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Direct Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Building Pressure Control, optional . . . . . . . . . . . . .12
Start-Up
Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-15
Direct Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-18
Operation
Optional VAV Units. . . . . . . . . . . . . . . . . . . . . . . . . .19
Optional Recirculating Units . . . . . . . . . . . . . . . . . .20
Electrical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20-21
Troubleshooting
Blower Does Not Operate . . . . . . . . . . . . . . . . . . . .22
Motor Overamps . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Insufficient Airflow . . . . . . . . . . . . . . . . . . . . . . . . . .24
Too Much Airflow . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Excessive Noise or Vibration . . . . . . . . . . . . . . . . . .25
Heater Does Not Operate (Pilot Ignition) . . . . . . 26-28
Heater Does Not Operate (Direct Spark) . . . . . . 29-30
Maintenance
Routine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
V-Belt Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Wheels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Fall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
High Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Gas Train. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Reference
Typical Gas Train Layout . . . . . . . . . . . . . . . . . . 33-34
Control Center Layout . . . . . . . . . . . . . . . . . . . . . . .35
Maintenance Log. . . . . . . . . . . . . . . . . . . . . Backcover
Warranty. . . . . . . . . . . . . . . . . . . . . . . . . . . . Backcover
Model VSU Make-Up Air
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Product Overview
Subassemblies
The model is a vertically-configured make-up air unit
designed for outdoor installations. It contains a highly
efficient direct-fired gas burner to provide a heat source
for the building or to simply temper the air. The unit is
designed to provide sufficient air to replace air that is
exhausted from the building and will also produce heat
as needed. The make-up air volume produced by the
unit can be regulated in a number of different ways,
depending on the characteristics of the building.
Filter Section / Vertical Mounting Stand
The filter section of the unit is factory installed in the
mounting stand and shipped ready for installation on
the concrete mounting pad. Each filter unit has a large
access panel on the control end of the unit except for
the housing size 50, which has an access door on both
ends. Filters are either 2 in. thick pleated paper or 2 in.
thick permanent metal type. Filters are changed by
removing the access door(s) and sliding the filters in or
out on their tracks.
The unit draws in fresh, outdoor air through a filter bank
in the bottom of the unit and it then moves upward
through a combustion chamber or through an optional
burner bypass damper. A blower mounted in the top of
the unit then forces the air into the building ductwork.
The unit’s vertical mounting stand is fabricated of
heavy-gauge, painted angle iron and flat stock steel.
The nominal 24 in. high stand will support the entire unit
so that the bottom of the filter unit is held 24 in. above
ground level. For housing size 50, a nominal 48 in. high
stand is minimum. In locations where heavy snowfall
is common, greater minimum clearance should be
specified in order to minimize the possibility of clogging
filters with snow or debris. The stand with filter bank is
shipped to the jobsite as a separate assembly. The unit
filter bank is permanently installed in the mounting stand
prior to shipment.
Airflow Arrangement
The unit can be ordered in a number of different
configurations to provide 100% outdoor air or 80%
recirculated air and 20% outdoor air. These units
can also be ordered with a variable air volume (VAV)
capability for flexibility in response to building air
handling needs.
100% Outdoor Air
If the unit is configured only for 100% outdoor air, it
draws outdoor air as needed through the filter bank
at the bottom. The air moves upward through the
combustion chamber and then it is blown into the
building through user-supplied ductwork. The supply air
volume is typically constant and can only be altered by
changing the blower or motor pulleys.
80/20 Recirculated Air
Optional Service Platform
When the unit is used as a primary heat source for
the building, the unit will draw 80% of the needed air
from the building and mix it with a minimum of 20%
fresh outdoor air. Outdoor air is drawn through the
combustion chamber and then mixed with the indoor
air after the direct-fired gas heater has heated the air.
The supply air volume is typically constant but the
percentage of recirculated air can be modulated.
A service platform
is available
for permanent
attachment to the
mounting stand.
The platform
is shipped
unassembled
and requires
field assembly.
Variable Air Volume (VAV)
The VAV function can be selected when the outdoor air
volume required by the building varies. This requires
the installation of one bypass damper and selection of
an appropriate motor/blower control system. This may
involve installation of a Variable Frequency Drive (VFD)
controller. Both bypass damper and VFD are factory
installed.
It is attached to the
vertical mounting stand
by installing bolts with spacers
between the two assemblies.
The service platform should be
attached to the unit only after the
burner and blower assemblies are
permanently set in place.
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Burner, Blower and Control Center Section
The blower section of the unit consists of one motor and
either one or two forward curved blowers. It is the top-
most assembly in the unit. If two blowers are used, their
drive shafts are connected and driven by a single motor.
Supply air discharge openings may be located either on
the side wall of the unit for horizontal discharge, or may
be configured for upblast discharge through the roof of
the unit. One large access door is located directly above
the control center, for inspection and maintenance of
the motor and blower(s).
The burner section, blower section and control center
of the unit are all combined into one assembly which
is installed in the field on top of the filter and stand
section. The burner section is the lowest part of the
burner / blower unit and it sits directly on the filter
assembly. The burner section contains the gas train
with its own access door and directly above that is
the control center door. A number of different options
are available for the gas train, whick include type, size
and location of burners and many different ignition and
safety controls.
Blowers
Control Center/
Gas Train
Burner
Filters
Open View
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Dampers
There are four locations where optional dampers may
be found. An optional motorized intake damper may be
located horizontally on the bottom of the burner section.
A patented passive control damper may be found
adjacent to the burner opening plates if a VAV is ordered
and a motorized damper may be installed vertically on
the side of the burner section if recirculating air mode is
chosen. In addition, an outlet damper may be shipped
with the unit for field installation.
Optional Field-Installed
Outlet Damper
Gas Train
(Burner Subassembly)
Burner Subassembly
The burner subassembly consists of the gas train with
its controls, valves, pressure regulator, burner(s), and
combustion chamber. The primary gas connection to
the gas train is made through the side wall grommet
into the factory-supplied female pipe fitting.
Optional Motorized
Recirculating Damper
Passive Control Damper
Control Center
The control center is located on the end of the unit,
directly above the gas train access door. The control
center contains electronic components and some
elctromechanical devices that monitor and control
the operation of the entire unit. A unit-specific wiring
diagram is affixed to the inside of the access door.
Optional Motorized
Intake Damper
High voltage supply wiring
terminates at a manual on/off
switch located on the face or
the side of the unit, adjacent to
the control center.
Low voltage control wiring from
the building terminates on the
terminal strips.
Manual High Voltage
On/Off Switch
with Lockout
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Installation
Concrete Slab
The first step in unit installation is to pour a concrete
slab capable of holding the unit weight as a base. The
slab should have a proper gravel drainage bed.
Burner/Blower Section
Use a crane and a spreader bar hooked to the factory
lifting lugs (shown below) to lift and center the unit onto
the filter stand section. The sections should be caulked
together.
Spreader Bar
Concrete Slab Dimensions
Housing Size
A
B
C
D
E
20
30
40
50
64
77
78
87
64
42
42
42
42
40
52
54
63
40
76
53
135
180
111
153
All dimensions are shown in inches.
NOTE
If optional service platform is included, a minimum of
42 inches must be added to Dimension B.
Building Wall
Approx. Stand Feet Locations
Concrete Slab
D
A
E
12
12
Install Ductwork
C
B
This table shows the duct sizes and straight lengths
recommended for optimal performance (AMCA
Publication 201-90). Using duct sizes less than
recommended will affect fan performance. Good
duct installation practices should be followed for the
remaining ductwork.
Concrete Slab and Unit Footprint
Service and Access Clearance
The slab should be positioned to allow 3 feet of
clearance on the control end of the unit and 2 feet of
clearance on the other three sides. Housing size 50
requires 3 feet of clearance on both ends because of
filters access. Note that the concrete forms a 1 foot
wide apron on all four sides of the unit unless a 42 in.
extension is added to the control end of the unit.
Recommended Supply Ductwork Sizes
VSU
Blower Size
Duct Size
(in.)
Straight Duct Length
(in.)
108
109
110
112
115
118
120
218
220
225
230
10x13
14x13
16x14
18x16
19x16
24x22
28x28
68x24
68x26
104x37
104x37
32
38
42
Clearance to Combustibles
48
Floor
Top
Sides
Ends
49
0 in.
(0 mm)
0 in.
(0 mm)
0 in.
(0 mm)
0 in.
(0 mm)
Insulated/
Units
64
Non Insulated
Units
0 in.
(0 mm)
6 in.
6 in.
6 in.
79
(152.4 mm) (152.4 mm) (152.4 mm)
114
118
175
203
Clearance to combustibles is defined as the minimum distance required
between the heater and adjacent combustible surfaces to ensure the
adjacent surface’s temperature does not exceed 90 degrees above the
ambient temperature.
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Complete Installation
Installation of Optional Service Platform
A typical horizontal discharge installation is shown. Gas
and/or electrical lines can be connected at this time.
For upblast units, a duct elbow may be needed to turn
the ductwork into the building. Follow proper ductwork
methods recommended by AMCA to make this elbow to
minimize duct losses.
TOOLS REQUIRED
• (2) 9/16 in. sockets or wrenches
• Drill with 7/16 in. drill bit and 5/16 in. drill bit
• A crane or forklift is recommended for assembly and
attachment.
Service Platform Material List
(1) Left Hand Rail with
(1) Right Hand Rail
(2) Legs
Safety Chains
(1) Platform Base Unit with
predrilled holes for hand
rails, legs and attachments.
(1) Leg Cross Member
Fasteners
Hex Head Bolts
3/8 in. x 1-1/2 in.
(3)
(2)
Thread Cutting
Screws
3/8 in. x 1 in.
Hex Head Bolts
3/8 in. x 3/4 in.
(18)
(27)
Hex Head Nuts
3/8 in.
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6. Facing the control panel side of the unit, find the
center of the housing and drill a (7/16 in.) hole
through the housing and support stand (3/8 in.)
above the form line as shown in Figure C.
Assembly
1. Position platform base as shown below in Figure A
with the grate side up.
2. Attach the left and right handrails to the platform
base with (3/8 in. x 3/4 in.) hex head bolts and (3/8
in.) hex nuts as shown in Figure A. Use six bolts and
nuts on each rail.
3/8 inch
3. Raise the platform base, grate side up, with a crane
or forklift.
Form Line
4. Attach legs to the slots on sides of platform base
with two (3/8 in. x 3/4 in.) hex head bolts and
(3/8 in.) hex nuts.
12 inches
12 inches
Figure C
Next, drill two more (7/16 in.) holes through the
housing and support stand (12 in.) on either side of
the center hole, (3/8 in.) above the form line. These
holes are used to attach the platform base to the
unit.
7. Attach the service platform to the control panel
side of the housing by inserting the three (3/8 in. x
1-1/2 in.) bolts of platform base into the three holes
of the housing. Securely fasten with three (3/8 in.)
hex nuts.
8. Level service platform if necessary by adjusting
legs and then attach leg cross member with two
(3/8 in. x 3/4 in.) hex head bolts and 3/8 in. hex head
nuts.
9. Securely fasten all nuts and bolts. Make sure all
nuts and bolts are tight.
10. Attach arm rails of service platform to the housing
by first drilling a 5/16 in. hole through the housing at
the attachment point as shown in Figure D. Secure
arm rails to the housing with (3/8 in. x 1 in.) thread
cutting screws. Be sure not to over-tighten screws.
11. Attach safety chains to the right hand rail, across
the entryway. Assembly is complete.
Attachment Points
for Step 11
Figure A
5. Fasten three (3/8 in. x 1-1/2 in.) hex head bolts into
the side of the platform
base. Secure each bolt
with two (3/8 in.) hex
head nuts placed back
to back on each bolt as
shown in Figure B. These
bolts will be used to
attach the platform base
to the unit.
Figure B
Figure D
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Installation of Electrical Wiring
must be compatible with the ratings on the nameplate,
supply power voltage, phase and amperage. Consult
ANSI/NFPA 70 and CSA C22.1 for proper conductor
sizing.
IMPORTANT
Before connecting power to the unit, read and
understand the following instructions and wiring
diagrams. Complete wiring diagrams are attached on
the inside of the control center door(s).
Connect the Main Power
Connect the main power lines to the disconnect switch
and main grounding lug(s). Torque field connections to
manufacturer’s recommendations.
IMPORTANT
All wiring should be done in accordance with the
latest edition of the National Electric Code ANSI/
NFPA 70 and any local codes that may apply. In
Canada, wiring should be done in accordance with
the Canadian Electrical Code.
Wire the Optional Convenience Outlet
The convenience outlet requires a separate 115V power
supply circuit. The circuit must include short circuit
protection which may need to be supplied by others.
IMPORTANT
Wire the Optional Accessories
Reference the ladder diagram on the inside of the
control center door for correct wiring of the following
accessories:
The equipment must be properly grounded. Any
wiring running through the unit in the airstream must
be protected by metal conduit, metal clad cable or
raceways.
• Selectra Stat
• Room Override
• Blower Switch
• Heat Switch
• Indicating Lights
• Dirty Filter Indicator
• TSCP
CAUTION
If replacement wire is required, it must have a
temperature rating of at least 105ºC, except for an
energy cut-off or sensor lead wire which must be
rated to 150ºC.
• KSCP
NOTE
Wiring to the Selectra Stat should be in separate
conduit or run with shielded cable.
DANGER
High voltage electrical input is needed for this
equipment. This work should be performed by a
qualified electrician.
NOTE
TSCP has number-to-number wiring.
NOTE
CAUTION
Large evaporative coolers may require a separate
power supply.
Any wiring deviations may result in personal injury or
property damage. Manufacturer is not responsible
for any damage to, or failure of the unit caused by
incorrect final wiring.
Connect Field-Wired Low Voltage Components
Most factory-supplied electrical components are
prewired. To determine what electrical accessories
require additional field-wiring, refer to the unit-specific
wiring diagram located on the inside of the control
center access door.
IMPORTANT
Manufacturer’s standard control voltage is 24 VAC.
Control wire resistance should not exceed 0.75 ohms
(approximately 285 feet total length for 14 gauge
wire; 455 feet total length for 12 gauge wire). If the
resistance exceeds 0.75 ohms, an industrial-style
plug-in relay should be wired in place of the remote
switch. The relay must be rated for at least 5 amps
and have a 24 VAC coil. Failure to comply with these
guidelines may cause motor starters to chatter or not
pull in, resulting in contactor failures and/or motor
failures.
The low voltage control circuit is 24 VAC and control
wiring should not exceed 0.75 ohms.
Control wires should not be run inside the same conduit
as that carrying the supply power. Make sure that
field-supplied conduit does not interfere with access
panel operation. All low voltage wiring should be run in
conduit wherever it may be exposed to the weather.
If wire resistance exceeds 0.75 ohms, an industrial-
style, plug-in relay should be added to the unit control
center and wired in place of the remote switch (typically
between terminal blocks R and G on the terminal strip).
The relay must be rated for at least 5 amps and have a
24 VAC coil. Failure to comply with these guidelines may
cause motor starters to “chatter” or not pull in which
can cause contactor failures and/or motor failures.
Determine the Size of the Main Power Lines
The unit’s nameplate states the voltage and the unit’s
MCA. The main power lines to the unit should be sized
accordingly. The nameplate is located on the outside of
the unit on the control panel side.
Determine the Size of Electric Heater Wiring
An optional electric heater may require a separate
power supply. The power connection should be made
to the factory provided electric heater disconnect and
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Installation of Direct Gas Piping
Determine the Supply Gas Requirements
The unit’s direct gas nameplate states the requirements
for the gas being supplied to the unit. The direct gas
nameplate is located on the outside of the unit on the
control center side.
Minimum gas pressure for
maximum output
IMPORTANT
All gas piping must be installed in accordance
with the latest edition of the National Fuel Gas
Code ANSI/Z223.1 and any local codes that may
apply. In Canada, the equipment shall be installed
in accordance with the Installation Code for Gas
Burning Appliances and Equipment (CGA B149) and
Provincial Regulations for the class. Authorities having
jurisdiction should be consulted before installations
are made.
MAX BTU/HR
BTU/H MAX
MIN BTU/HR
BTU/H MIN
NORMAL MANIFOLD
PRESSURE
PRESSION DÕADMISSION
NORMALE
MIN GAS PRESSURE
FOR MAX OUTPUT
PRESSION DE GAZ MIN
POUR PUISSANCE MAX
WARNING
“ WC
“ WC
“ WC
“ WC
“ WC
All components of this or any other gas-fired heating
unit must be leak tested prior to placing the unit into
operation. A soap and water solution should be used
to perform this test. NEVER test for gas leaks with an
open flame.
MIN GAS
PRESSURE
PRESSION DE GAZ
MAX GAS
PRESSURE
PRESSION DE GAZ
MAX
MIN BURNER
MAX BURNER
PRESSURE DROP
PERTE MIN DE PRESSION
DANS LE BRULEUR
PRESSURE DROP
PERTE MAX DE PRESSION
DANS LE BRULEUR
PSI
TYPE OF GAS
NATURE DU GAZ
DESIGN ∆T
∆T NORMALE
WARNING
F
If pressure testing in excess of 1/2 psig (3.5 kPa), the
heater and manual shutoff valve must be disconnected
from the supply gas line.
EQUIPPED FOR
CONCU POUR
AGAINST
CONTE
EXTERNAL STATIC PRESSURE
SCFM
“ WC
PRESSION STATIQUE EXTERIEURE
WARNING
Type of gas
Maximum gas pressure
Direct Gas Nameplate
If pressure testing at or below 1/2 psig (3.5 kPa), the
heater must be isolated from the supply gas line by
closing its manual shutoff valve.
IMPORTANT
Install Additional Regulator if Required
When the supply gas pressure exceeds the maximum
gas pressure shown on the direct gas nameplate, an
additional regulator (by others) is required to reduce the
pressure. The regulator must have a listed leak limiting
device or it must be vented to the outdoors.
All piping should be clean and free of any foreign
matter. Foreign material entering the gas train can
damage the valves, regulators and burner.
IMPORTANT
Do NOT connect the unit to gas types other than
what is specified and do NOT connect the unit to
gas pressures that are outside of the pressure range
shown on the label.
NOTE
The regulator located inside the unit is used to adjust
the unit’s maximum output temperature.
NOTE
When connecting the gas supply, the length of the
run must be considered in determining the pipe size
to avoid excessive pressure drop. Refer to a Gas
Engineer’s Handbook for gas pipe capacities.
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Connect the Supply Gas Line
Installation of Building Pressure
Control (optional)
Mount Pressure Tap
Using the factory provided bracket, mount the pressure
tap to the outside of the
unit. Choose a location
out of the prevailing
A manual shut off valve (gas cock), 1/8 in. plugged test
port and 6 in. drip leg must be installed prior to the gas
train. The valve and the test port must be accessible for
the connection of a test gauge. Supply gas connections
must be made by a qualified installer and are not
furnished by manufacturer.
To
Controls
winds and away from
supply or exhaust fans
to assure accurate
readings.
Gas Cock
Ground Joint Union
From
Gas
Supply
Run Pressure Tap Lines
Run a pressure tap line from the pressure tap on the
outside of the unit to the low pressure tap on the back
of the photohelic gauge. Run a second pressure tap line
from the high pressure tap on the back of the photohelic
gauge to the space. Fifty feet of tubing is supplied with
the unit.
1/8 in. Plugged Tap
6 in. Trap
Supply Gas Line
WARNING
Set the Building Pressure
The pressure gauge is used to set the desired building
pressure. The pressure is set by adjusting the knobs for
the upper and lower pressure limits. Typical settings are
0.0 in. wg for the lower and 0.10 in. wg for the upper
pressure setting.
Reference the National Fuel Gas Code for additional
vent line requirements.
Pipe the Optional Vent Line
If an optional vent line is located between the safety
shutoff valves it must be piped to the outdoors.
High Pressure Tap
Vent Line Solenoid
to space
Factory Wiring
To Outdoors
Low Pressure Tap
to outside
Connections for Photohelic Gauge
To Burner
From Supply
Safety
Shut-off Valves
Pressure Indicating
Needle
Pressure Setting
Needles
Optional Vent Line
Test the System for Leaks
Check both the supply lines and the factory piping for
leaks. Apply a soap and water solution to all piping and
watch for bubbling which indicates a leak.
Pressure Setting Knobs
WARNING
NEVER test for a gas leak with an open flame.
NOTE
Typical Photohelic Gauge Settings
The factory piping has been checked for leaks, but
should be rechecked due to shipping and installation.
Model VSU Make-Up Air
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Start-Up - Checklist
Unit Model Number _______________________________
Start-Up Direct Gas (Pilot Ignition) – refer to
Start-Up - Direct Gas section for further detail.
(e.g. VSU-H20)
o Check supply gas pressure
________ Maximum
________ Minimum
________ Actual
Unit Serial Number _______________________________
(e.g. 10111000)
Start-Up Date
_______________________________
Start-Up Personnel Name __________________________
Start-Up Company _______________________________
o Check Pilot Gas Pressure
________ Actual Setting
Typical 3.0 in. wg
Phone Number
_______________________________
o Set optional High Gas Pressure Switch
________ Actual Setting
Typical 8.0 in. wg
Pre Start-Up Checklist – check boxes as items
are completed.
o Check tightness of all factory wiring connections
o Verify control wiring wire gauge
o Hand-rotate blower to verify free rotation
o Verify supply voltage to the main disconnect
o Verify the supply gas pressure
o Verify remote controls wiring
o Set optional Low Gas Pressure Switch
________ Actual Setting
Typical 3.0 in. wg
o Set Burner Pressure Differential
________ Actual Setting
Typical 0.65 in. wg
o Set the maximum firing rate
________ temp rise
o Check V-belt drive for proper alignment and
tension
Start-Up Blower Checklist – refer to Start-Up -
Blower section for further detail.
o Set the minimum firing rate
o Check line voltage
L1-L2 __________
L2-L3 __________
L1-L3 __________
________ check
o Set the unit’s operating temperature
________ ºF
o Check blower rotation
o Check for vibration
o Supply fan RPM
o Motor nameplate amps
o Actual motor amps
o Actual CFM delivered
_________ RPM
_________ Amps
_________ Amps
_________ CFM
Start-Up Direct Gas (Direct Spark) – refer to
Start-Up - Direct Gas section for further detail.
o Check supply gas pressure
________ Maximum
________ Minimum
________ Actual
Optional Accessories – refer to Start-Up - Blower,
Set-Up Optional Components, pg. 15 for further detail.
o Heating Inlet Air Sensor
________ Actual Setting
Typical setting 60º-70ºF
o Cooling Inlet Air Sensor
________ Actual Setting
Typical setting 75ºF
o Set optional High Gas Pressure Switch
________ Actual Setting
Typical 8.0 in. wg.
o Set optional Low Gas Pressure Switch
________ Actual Setting
Typical 3.0 in. wg.
o Set Burner Pressure Differential
________ Actual Setting
Typical 0.65 in. wg
o Set the maximum firing rate
________ temp rise
o Building Freeze Protection
________ Actual Setting
Typical setting 5 minutes; 45ºF
o Dirty Filter Gauge
________ Actual Setting
Typical setting varies
o Set the minimum firing rate
________ check
o Set the unit’s operating temperature
________ ºF
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Start-Up - Blower
Check for Vibration
WARNING
Check for unusual noise, vibration or overheating of the
bearings. Reference the Troubleshooting section for
corrective actions.
Check the housing, blower, and ductwork for any
foreign objects before running the blower.
WARNING
IMPORTANT
Disconnect and lock-out all power and gas before
performing any maintenance or service to the unit.
Failure to do so could result in serious injury or death
and damage to equipment.
Excessive vibration may be experienced during
the initial start-up. Left unchecked, it can cause a
multitude of problems including structural and/or
component failure.
IMPORTANT
SPECIAL TOOLS REQUIRED
Generally, fan vibration and noise is transmitted
to other parts of the building by the ductwork. To
minimize this undesirable effect, the use of heavy
canvas duct connectors is recommended.
• Voltage Meter (with wire probes)
• Amperage Meter
• Pressure Gauges – (refrigerant)
• Tachometer
• Thermometer
• Incline manometer or equivalent
Motor Check
Measure the motor’s voltage, amps and RPM. Compare
to the specifications. Motor amps can be reduced by
lowering the motor RPM or increasing system static
pressure.
Check the Voltage
Before starting the unit, compare the supplied voltage,
hertz, and phase with the unit and motor’s nameplate
information.
IMPORTANT
Voltage, Hertz, Phase
Additional starters and overloads may be provided in
the make-up air control center for optional exhaust
blowers. Any additional overloads must be checked
for proper voltage, amps and RPMs.
VOLTS
HZ
EXH HP
MOP
PH
SUP HP
MCA
Air Volume Measurement and Check
Measure the unit’s air volume (cfm) and compare it with
the rated air volume. If the measured air volume is off,
adjust the fan’s RPM by changing/adjusting the drive.
Electrical Nameplate
Check the Blower Rotation
Open the blower access door
and run the blower momentarily
to determine the rotation. Arrows
are placed on the blower scroll to
indicate the proper direction or
reference the example shown to
the right.
NOTE
The most accurate way to measure the air volume is
by using a pitot traverse method downstream of the
blower. Other methods can be used, but should be
proven and accurate.
Blower
Housing
Blower Rotation
IMPORTANT
Changing the air volume can significantly increase
the motor’s amps. If the air volume is changed,
the motor’s amps must be checked to prevent
overloading the motor.
NOTE
To reverse the rotation on three phase units,
disconnect and lock-out the power, then interchange
any two power leads.
NOTE
NOTE
To ensure accuracy, the dampers are to be open
when measuring the air volume.
To reverse the rotation on single phase units,
disconnect and lock-out the power, then rewire the
motor per the manufacturer’s instructions.
IMPORTANT
If the blower is rotating in the wrong direction, the unit
will move some air, but will not perform as designed.
Be sure to perform a visual inspection to guarantee
the correct blower rotation.
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Start-Up - Direct Gas
Set-Up Optional Components
IMPORTANT
Adjust the settings on the optional components. See
the unit’s specific wiring diagram located on the access
door or the unit.
For proper unit function and safety, follow the start-up
procedure in the exact order that it is presented.
IMPORTANT
• Heating Inlet Air Sensor
Typical setting: 60-70ºF
This start-up should begin after all of the installation
procedures and the blower start-up have been
completed.
• Building Freeze Protection
Typical setting: 5 minutes; 45ºF
Check the Supply Gas Pressure
• Dirty Filter Gauge
Check the supply gas pressure and compare it with
the unit’s nameplate pressure requirements. Adjust
the supply regulator as needed until the supply gas
pressure is within the specified range. The direct gas
nameplate is located on the outside of the unit on the
Typical setting: Settings vary greatly for each unit.
(see Reference section for adjusting information)
control center side.
Minimum and maximum gas
pressures for maximum output
MAX BTU/HR
BTU/H MAX
MIN BTU/HR
BTU/H MIN
NORMAL MANIFOLD
PRESSURE
PRESSION DÕADMISSION
NORMALE
MIN GAS PRESSURE
FOR MAX OUTPUT
PRESSION DE GAZ MIN
POUR PUISSANCE MAX
“ WC
“ WC
“ WC
“ WC
“ WC
MIN GAS
PRESSURE
PRESSION DE GAZ
MAX GAS
PRESSURE
PRESSION DE GAZ
MAX
MIN BURNER
MAX BURNER
PRESSURE DROP
PERTE MIN DE PRESSION
DANS LE BRULEUR
PRESSURE DROP
PERTE MAX DE PRESSION
DANS LE BRULEUR
PSI
TYPE OF GAS
NATURE DU GAZ
DESIGN ∆T
∆T NORMALE
F
EQUIPPED FOR
CONCU POUR
AGAINST
CONTE
EXTERNAL STATIC PRESSURE
“ WC
SCFM
PRESSION STATIQUE EXTERIEURE
Type of gas
Direct Gas Nameplate
Check the Pilot Gas Pressure
Check the pilot gas pressure. The recommended
gas pressure is 3 in. wg. Adjust the pilot regulator as
needed. See the Gas Train Layout in the Reference
section for the location of the pilot pressure test port
and pilot regulator.
Check the Optional High and Low Gas Pressure
Switches
Check the settings on the high and low gas pressure
switches. The high gas setting is typically 8 in. wg
(2 kPa) and the low gas setting is typically 3 in. wg
(0.7 kPa). The switches are set at the factory and should
not need adjustment. Adjust the settings if needed. See
the Gas Train Layout in the Reference section for the
high and low pressure switch location.
IMPORTANT
The purpose of the high and low gas pressure
switches is to automatically shut down the burner
if the inlet gas pressure is too low for the burner to
safely light, or if the manifold pressure is too high for
the burner to operate properly.
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Set the Burner Air Pressure Differential
NOTE
With the fan running and discharging 70ºF (21ºC) air,
connect a U-Tube manometer to the outer sensing
probes (see below) and measure the static pressure
across the burner.
The pressure drop was set at the factory and may not
need adjustment.
NOTE
When required pressure is obtained, be sure to
reconnect the outer sensing probes.
Outer Sensing Probes
IMPORTANT
This process may need to be repeated until the proper
pressure is achieved. This adjustment will change the
air quantity delivered by the unit and therefore the air
quantity delivered should be rechecked. Refer to the
Blower Start-Up section.
7
0.625 - 0.675 in. wc
6
U-Tube
Manometer
NOTE
To increase the static pressure decrease the opening.
To decrease the static pressure increase the opening.
Measuring the Pressure Drop
Set the Maximum Firing Rate
Monitor the unit’s actual temperature rise by placing
a thermocouple in the unit’s inlet and a second in the
discharge, three duct diameters downstream of the burner.
IMPORTANT
Proper air velocity over the burner is critical on direct-
fired gas units. If the air velocity is not within the unit
specifications, the unit will not operate efficiently,
may have sporadic shutdowns, and may produce
excessive carbon monoxide (CO) or other gases.
Send the unit to maximum fire by disconnecting and
isolating the wire connected to Terminal 3 on the Maxitrol
14 or the Maxitrol 44. See images on page 18.
While monitoring the units temperature rise, set the
maximum firing rate by adjusting the regulator until the
designed temperature rise is achieved. After setting the
maximum firing rate, reconnect the wire to the amplifier.
The proper static pressure should be between 0.625
and 0.675 in. wg (155.68 and 168.64 Pa). If needed,
evenly adjust the baffles on both sides of the burner,
keeping the burner centered in the opening until the
required pressure is obtained.
NOTE
Do not set the burner maximum firing rate based on gas
pressure. It should be set based on the unit’s designed
temperature rise shown on the direct gas label.
Burner
MIN GAS
MAX GAS
PRESSURE
PRESSION DE GAZ
PRESSURE
PRESSION DE GAZ
MAX
“ WC
“ WC
“ WC
PSI
F
Adjustable
Baffle
Adjustable
Baffle
MIN BURNER
MAX BURNER
PRESSURE DROP
PERTE MIN DE PRESSION
DANS LE BRULEUR
PRESSURE DROP
PERTE MAX DE PRESSION
DANS LE BRULEUR
Airflow
Airflow
TYPE OF GAS
NATURE DU GAZ
DESIGN ∆T
∆T NORMALE
EQUIPPED FOR
CONCU POUR
AGAINST
CONTE
EXTERNAL STATIC PRESSURE
“ WC
SCFM
Burner and Baffles
PRESSION STATIQUE EXTERIEURE
Direct Gas Nameplate
Maximum firing
rate adjustment
Combined Regulator Valve
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Set the Minimum Firing Rate
IMPORTANT
Disconnect and isolate one of the wires running to the
modulating valve to send the unit to its minimum firing
rate. Set the minimum firing rate by adjusting the needle
valve indicated.
Setting the maximum firing rate during mild weather
conditions may cause the high limit to trip out during
extreme conditions requiring manual resetting.
NOTE
After setting the minimum firing rate, shut off the pilot
to ensure that the flame safeguard can still read the
main flame signal. Reconnect the wire to the modulation
valve and open the pilot shut-off valve.
Gas trains are equipped with either separate
regulators and modulating valves or with a combined
modulating valve.
NOTE
IMPORTANT
Clockwise rotation increases the temperature rise,
counterclockwise rotation decreases the temperature
rise.
The proper minimum firing rate setting results in a
small ribbon of continuous flame which covers the
flame rod and runs across the entire burner.
NOTE
IMPORTANT
The minimum setting for the maximum firing rate
may be higher than required. This is acceptable. The
burner will modulate as needed.
Do not allow the disconnected wire to come in
contact with a potential ground. Damage to the
amplifier or transformer could result.
IMPORTANT
Regulators and Modulating Valves
On units with a 42 inch or greater burner, the flame
safeguard will automatically shut off the pilot after the
burner has been ignited.
Remove one wire to
send the unit to the
minimum firing rate
Remove cap to access
maximum firing rate
adjustment
NOTE
Gas trains are equipped with either separate
regulators and modulating valves or with a combined
modulating regulator.
NOTE
Adjusting the maximum and minimum firing rate
requires the inlet air sensor to be set higher than the
outdoor air temperature in order to start the burner(s).
Once high and low fire have been set, the inlet air
sensor should be set to the desired temperature.
Minimum
firing rate
adjustment
Separate Regulator and Modulating Valves
NOTE
Counterclockwise rotation increases the minimum fire
rate setting, clockwise rotation decreases the setting.
Minimum firing
rate adjustment
Maximum firing
rate adjustment
Remove one wire to send the unit
to the minimum firing rate
Combined Modulating Regulator
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Set the Unit’s Operating Temperature
Set the operating temperature. The operating
temperature setting depends on which Maxitrol
controller is used.
Maxitrol SC25S: The SC25S is an analog signal
converter that will change a 0-10 VDC or a 4-20 mA
control signal provided by an owner supplied Building
Management System into an output level capable of
driving one or more modulating gas valves. The SC25S
also limits the minimum and maximum discharge
air temperatures. Reference the unit-specific wiring
diagram and Maxitrol data sheets included in the IOM
packet.
Maxitrol Series 14 – 8 Terminals: The Maxitrol
Series 14 should be set to the desired discharge
temperature mode. Place dipswitch in the “UP” position
for local control and in the “DOWN” position for remote
control. Keep LFST dipswitch in the “UP” position at all
times for 10 second delay.
Fig. A is required for remote control.
Terminal 3 - Remove wire to
send unit into maximum fire.
Discharge
temp
dipswitch
Low fire
setting
(LFST)
Maxitrol SC25S
dipswitch
Flame Signal Check - Pilot Ignition
To measure the flame signal connect a standard DC
voltmeter to the flame amplifier test jacks + and - (com)
Set the discharge temp
Typical: 65°F
Minimum: Typical: 55°F
Maximum: Typical: 90°F
Fig. A
Remote
controller
as shown to the
right. The flame
signal should be
above 1.25 VDC
and steady.
Maxitrol Series 14 — 8 terminals
Check the flame
signal with the
burner at pilot only,
minimum fire, mid
fire and high fire.
Maxitrol Series 44 – 9 Terminals: The Maxitrol
Series 44 should
be set to the
desired discharge
temperature
DC Voltmeter and
Set the space
Flame Amplifier
Typical: 70
ºF
temperature.
The temperature
selector is a stand-
alone dial. The
stand-alone dial
may be mounted
remotely.
IMPORTANT
If the flame signal is not above 1.25 VDC and steady,
consult the troubleshooting section.
Series 44 Temperature Setting
(shown as space temperature control)
Minimum discharge
temperature setting
(Typical: 50ºF)
Terminal 3 - Remove wire to
send unit into maximum fire.
Maximum discharge
temperature setting
(Typical: 100ºF)
Low fire time delay setting
(75% of maximum)
Maxitrol Series 44 — 9 terminals
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Building Pressure Control —
a variable frequency drive is
controlled according to input from
a pressure sensing device.
BLOWER
Operation - VAV Units (optional)
EXHAUST
(OPTIONAL)
SUPPLY
MAIN VALVES
HEAT
NOTE
Blower Start-Up, as shown on page 14, should be
performed before the blower is run.
DIRTY FILTERS
(OPTIONAL)
Turn both knobs to the upper
most pressure setting. You may
have to remove the outdoor
pressure tap tubing. VAV systems
should go to maximum speed. Set
both knobs at the lowest setting
and the VAV systems should go to
minimum speed.
70
75
65
60
55
80
85
90
NOTE
For maintenance issues associated with variable
frequency drives, consult the drive’s manual supplied
with the unit. The drives are programmed at the
factory and should not need any adjustment during
installation and start-up. For kitchen applications, the
drive may be located in the kitchen or in the unit.
PHOTOHELIC
GREENHECK
®
Building
Pressure Control
Reset the correct pressure limits
before starting the unit.
Pressure Indicating
Needle
Pressure Setting
Needles
Variable Volume Operation
This picture depicts a typical
photohelic setting. Typical
settings are 0.0 in. wg for
the lower pressure setting
and 0.10 in. wg for the upper
pressure setting. The needle
indicates a negative building
pressure. During correct
The variable volume option is recommended when
a building’s exhaust volume may vary. This option
enables the make-up air volume to track with the
exhaust volume, providing only the amount of make-
up air required. Control strategies include 2-speed and
modulating blowers. Before the unit is left in service, the
variable volume control system should be tested.
operation, the indicating
needle will remain between or
near the setting needles.
Pressure Setting Knobs
Photohelic Gauge
2-Speed
External Signal — a variable frequency drive is
controlled according to input from an external 2-10 VDC
or 4-20 mA signal (by others).
A variable frequency drive (VFD) is used to control
air volumes. The VFD can be switched to low or high
speed from a remote control panel. Turn the fan speed
switch on the remote control panel to each position and
confirm that the fan speed adjusts accordingly.
A 2 VDC or 4 mA signal will send the blower to low
speed. The blower will go to maximum speed with a 10
VDC or 20 mA signal.
Variable Kitchen Control — A variable frequency
drive is controlled by input from a remote speed control.
This unit allows automatic adjustment of make-up air
volumes based on varying cooking loads.
Modulating
Potentiometer Control — a variable frequency drive
is controlled by input from a remote
BLOWER
EXHAUST
speed selector (potentiometer). This
unit allows easy manual adjustment
of make-up air volumes. To test
potentiometer operation, turn the
potentiometer to the two extremes.
With variable volume, make sure the
fan goes to maximum and minimum
speed.
(OPTIONAL)
Burner Bypass Damper (optional)
The self-adjusting burner bypass damper is a device
SUPPLY
MAIN VALVES
HEAT
used in variable
volume units. Its
DIRTY FILTERS
Burner
70
75
65
80
85
(OPTIONAL)
60
55
90
function is to maintain
proper combustion by
providing a constant
airflow over the burner
when outside air
Bypass Damper
When the potentiometer is at 0, the
fan speed will be at its minimum.
When the potentiometer is at 100,
the fan will be at its maximum speed.
GREENHECK
®
volumes are changed.
It is located underneath
the burner as shown in
the picture.
Potentiometer
Control
Burner Bypass Damper
WARNING
The burner bypass damper is set-up at the factory.
The weights should not be adjusted in the field. The
damper may not fully close during minimum outside
air mode.
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Building Pressure Control — a
modulating spring return actuator
is used to control the return air
amounts. The return air damper
modulates from fully open to fully
closed based on a signal from a
remote pressure sensing device.
Operation - Recirculating Units
(optional)
BLOWER
EXHAUST
(OPTIONAL)
SUPPLY
MAIN VALVES
HEAT
NOTE
DIRTY FILTERS
(OPTIONAL)
70
75
65
60
55
80
85
Blower Start-Up, as shown on page 14, should be
performed before the blower is run.
90
Turn both knobs to the upper most
pressure setting. You may have
to remove the outdoor pressure
tap tubing. The return air damper
should close.
PHOTOHELIC
Recirculation Operation
The recirculation operation option is recommended
when the ventilation equipment provides the primary
source of heating for the space. A minimum of 20%
outdoor air is mixed with up to 80% filtered recirculated
air. Control strategies include 2-position and modulating
dampers.
GREENHECK
®
Building
Pressure Control
Set both knobs at the lowest setting and the damper
should open. It may take one to two minutes for the
damper to reach the desired position.
Before the unit is left in service, the recirculation control
system should be tested.
Reset the correct pressure limits before starting the unit.
Pressure Indicating
Needle
Pressure Setting
Needles
This picture shows a typical
photohelic setting. Typical
settings are 0.0 in. wg for the
lower and 0.10 in. wg for the
upper pressure setting. The
needle in this photo indicates
a negative building pressure.
During correct operation, the
indicating needle will remain
between or near the setting
needles.
2-Position Damper
A 2-position spring return actuator is used to control
the return air amounts. The
EXHAUST
BLOWER
(OPTIONAL)
damper moves from open to
SUPPLY
closed. If power is cut to the unit,
MAIN VALVES
HEAT
the outdoor air damper will fail to
RECIRCULATION
close.
Pressure Setting Knobs
DIRTY FILTERS
Turn the recirculating switch on
70
75
65
60
55
(OPTIONAL)
Photohelic Gauge
80
85
the remote control panel to each
position and confirm that the return
air damper adjusts accordingly.
The damper actuator may take a
few minutes to open or close.
90
GREENHECK
®
External Signal — a modulating spring return actuator
is used to control the return air amounts. Return air
damper modulates from fully open to fully closed based
on an external 2-10 VDC or 4-20 mA signal (by others).
2-Position
Damper Control
The return air damper will close with a 10 VDC or 20 mA
signal. The return air damper should open with a 2 VDC
or 4mA signal. The damper actuator may take a few
minutes to open or close.
Modulating
Potentiometer Control — a modulating spring return
actuator is used to control the return air amounts.
The return air damper modulates
from fully open to fully closed
based on a signal from a remote
potentiometer.
BLOWER
EXHAUST
Operation - Electrical
(OPTIONAL)
SUPPLY
MAIN VALVES
HEAT
Electrical Sequence
1. Exhaust Fan Contact (S1) Closed
(optional)
DIRTY FILTERS
To test potentiometer operation,
turn the potentiometer to the two
extremes. With 80/20 recirculation,
confirm that the return air damper
fully opens and fully closes. When
the potentiometer is at 0, the return
air damper will open. When the
potentiometer is at 100, the return
air damper will close. The damper
70
75
65
80
(OPTIONAL)
60
85
55
90
• Power passes to N.C. exhaust overload contact
(ST2 OL) (optional)
• Power passes to exhaust starter(s) ST2
GREENHECK
®
• N.O. exhaust starter switches are energized and
closed
Potentiometer
Control
• Power passes to exhaust fans
• Exhaust fan(s) (M2) start
actuator may take a few minutes to open or close.
2. Supply Fan Contact (S2) Closed
• Power passes through N.C. field supplied fire
contact (FSC)
• Power passes through N.O. exhaust fan contact
(ST2), which is closed when the exhaust relay
(ST2) is activated (optional)
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• Power passes to N.C. supply overload contact
(ST1 OL)
• Power passes through N.C. contact on optional
freeze protection timer (RT4) which remains
closed if the temperature has remained above the
set point
• Power passes to optional N.O. and N.C. high and
low gas pressure contacts (PS4 and PS3), which
are both closed if gas pressure is within the set
range
• Power passes to N.O. and N.C. airflow switches
(PS2) which are closed if there is proper airflow
across the burner
• Power passes to optional inlet damper which
opens
• Power passes to terminal TH on the Flame
Safeguard (FSG) which begins it’s sequence
(see Direct Gas Burner Sequence)
• When damper is fully opened, damper relay
(D1) is energized and optional N.O. damper limit
switch (DL1) closes
• Power passes to and energizes supply starter
relay (RF)
• Power passes to N.O. fan contact (RF), which is
energized and closed
• Supply starter (ST1) is energized
• Supply starter contact (ST1) closes and power
reaches and energizes supply fan
Direct Gas Burner Sequence - Pilot Ignition
1. Supply Fan Contact Closed
• Power passes to the supply fan and heat switch
2. Heat Contact Closed
• Power passes to the heat relay then to the Flame
Safeguard
3. Flame Safeguard (FSG) Sequence
• Checks for proper airflow
• Supply fan (M1) starts
3a. Heat Contact (S4) Closed - Pilot Ignition
• Verifies no flame present at burner
• Initiates 10 second prepurge
• Power passes to N.O. fan relay (RF) which is
energized and closed
• Sends power to open pilot gas valve (V1) and
energizes the spark generator (SG) (clicking of the
spark generator may be heard)
• Power passes to optional inlet air sensor contact
(TS4) which is energized and closed if the inlet air
temperature is below the set point
• Tries for up to 10 seconds to light pilot and
confirm flame
• Power passes to and energizes the heat relay
(RH)
• Powers the main gas valves open
• Shuts down spark generator
• N.O. heat relay contact (RH) closes
• Power passes to and energizes terminal 5 of the
• Continuously monitors the flame and airflow
Flame Safeguard (FSG). Power light on FSG is on.
• Performs self-diagnostic check every five
seconds.
• Power passes to N.C. high limit control contact
(HLC1) which is closed if temperature has
remained below set point
• Power passes to optional N.O. and N.C. high and
low gas pressure contacts (PS4 and PS3), which
are both closed if gas pressure is within the set
range
Direct Gas Burner Sequence - Direct Spark
1. Supply Fan Contact Closed
• Power passes to the supply fan and heat switch
• Power passes to terminal 6 of the Flame
Safeguard (FSG)
2. Heat Contact Closed
• Power passes to the heat relay then to the Flame
Safeguard
• Power begins direct gas burner sequence
(see Direct Gas Burner Sequence)
3. Flame Safeguard (FSG) Sequence
• Checks for proper airflow
3b. Heat Contact (S4) Closed - Direct Spark
• Power passes to N.O. fan relay (RF) which is
energized and closed
• Verifies no flame present at burner
• Initiates 15 second prepurge
• Power passes to optional inlet air sensor contact
(TS4) which is energized and closed if the inlet air
temperature is below the set point
• Sends power to open gas valve (V2) and
energizes the spark generator (clicking of the
spark generator may be heard)
• Power passes to and energizes the heat relay
(RH)
• Tries for up to 10 seconds to light and confirm
flame
• N.O. heat relay contact (RH) closes
• Shuts down spark generator
• Power passes to N.C. high limit control contact
(HLC1) which is closed if temperature has
remained below set point
• Continuously monitors the flame and airflow
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Troubleshooting
Blower Does Not Operate
No
Proper supply power at
main disconnect
Check main voltage.
Reference: Start-Up - Blower, Check the Voltage, pg. 14
Main disconnect (DS1) off.
Turn main disconnect (DS1) on.
Primary fuses blown.
Yes
Replace fuses.
No
No
No
No
No
24 VAC between
terminals R and X?
Main transformer (TR1) defective.
Yes
Replace transformer.
24 VAC between
terminals G and X?
Supply switch (S2) off.
Turn supply switch (S2) on.
Fire system contact (FSC) tripped/not installed.
Correct, replace.
Yes
24 VAC across
terminals 3 and X?
Supply fan overload (ST1 OL) tripped.
Reset and check motor amps.
Reference: Start-Up - Blower, Motor Check, pg. 14
Optional exhaust fan interlocks (ST2-ST5) open.
Correct, replace.
Yes
24 VAC across
terminals 4 and X?
Yes
(Optional) freeze protection (RT4) tripped.
Reset.
24 VAC across A2 and A1 on
supply contactor (ST1)
(Optional) damper limit switch (DL1) holding.
Wait for actuator to open fully or adjust limit switch.
(Optional) damper limit switch jumper missing.
Install jumper, reference the units ladder diagram for terminals.
Fan relay (RF) is not energized.
Yes
Check for loose connection. Repair or replace relay.
Broken fan belt.
Replace.
Reference: Maintenance - Routine, V-Belt Drives, pg. 31
Defective motor or capacitor.
Repair, replace.
Blown motor fuse.
Replace.
One or more legs of three-phase is out.
Restore missing legs.
At this time the supply contactor (ST1) should
pull in, passing power to the supply motor
and the blower should start.
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Troubleshooting
Motor Overamps
Yes
Yes
No
Air volume too high?
Adjust drives or increase external
static pressure as needed.
No
Reference: Start-Up-Blower, Air Volume Measurement and Check, pg. 14
Actual static pressure
lower than design?
No
Adjust drives to reduce blower RPM.
Reference: Start-Up-Blower, Air Volume Measurement and Check, pg. 14
Blower rotation correct?
Yes
Reverse blower rotation.
Reference: Start-Up - Blower, Check the Blower Rotation
No
Motor voltage correct?
Yes
Provide proper power supply.
Reference: Start-Up - Blower, Check the Voltage, pg. 14
Yes
Yes
Motor horsepower too low?
No
Resize motor.
Shorted windings in motor?
Yes
Replace motor.
Everything is working
properly, consult factory.
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Troubleshooting
Insufficient Airflow
Yes
Yes
Yes
Yes
Yes
Yes
Damper(s) not fully opened?
No
Adjust damper linkage(s), or replace faulty actuator(s).
Damper actuators may take a few minutes to open.
System static losses too high?
No
Reduce losses by improving ductwork.
Blower speed too low?
No
Adjust drives as needed.
Reference: Start-Up - Blower, Air Volume Measurement and Check, pg. 14
Filters dirty or clogged
No
Clean or replace filters.
Reference: Maintenance - Routine, Filters, pg. 31
Leaks in ductwork
No
Repair leaks.
Belt slipping
Yes
Replace or tighten belt.
Reference: Maintenance - Routine, V-Belt Drives, pg. 31
Everything is working properly,
consult factory.
Too Much Airflow
Yes
Yes
Yes
Blower speed too high?
No
Adjust drives as needed.
Reference: Start-Up - Blower, Air Volume Measurement and Check, pg. 14
Filters not in place?
No
Install filters.
Insufficient external
static pressure?
No
Increase external static pressure.
Everything is working properly,
consult factory.
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Troubleshooting
Excessive Noise or Vibration
Yes
Belts worn or loose?
Replace worn belts or tighten loose belts.
Reference: Maintenance - Routine, V-Belt Drives, pg. 31
No
No
Sheaves aligned?
Align sheaves.
Reference: Maintenance - Routine, V-Belt Drives, pg. 31
Yes
Yes
Yes
Yes
Wheel unbalanced?
Clean and/or balance wheel(s).
No
Bearings worn or
need lubrication?
Replace worn bearings or lubricate bearings as needed.
Reference: Maintenance - Routine, Bearings, pg. 32
No
Wheel rubbing on inlet?
Adjust wheel(s) or inlet.
No
At this time noise and vibration
should be at acceptable levels.
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Troubleshooting
Heater Does Not Operate (Pilot Ignition)
Does not attempt to light (No visible spark)
No
No
No
24 VAC between
terminals W1 and X?
Heat switch (S4) off.
Turn heat switch (S4) on.
Heat switch not wired.
Wire heat switch (S4).
Yes
115 VAC between
terminals 102 and 101?
Primary fuses blown.
Replace fuses.
Main transformer (TR4) defective.
Replace transformer.
Yes
115 VAC between
terminals 103 and 101?
(Optional) inlet air sensor (TS4) holding.
Adjust TS4 setting.
Reference: Start-Up - Blower, Set-Up Optional Components, pg. 15
Heat relay (RH) defective.
Yes
Replace heat relay (RH).
The power light on the flame safeguard should
blink approximately every 5 seconds as it
performs a self-diagnostics check.
No
No
No
115 VAC between
terminals 104 and 101?
High limit (HLC1) tripped.
Reset or replace high limit (HLC1).
Check on cause of control loss.
Yes
115 VAC between
terminals 106 and 101?
(Optional) high/low gas pressure switch(es)
(PS3 and PS4) tripped.
Correct gas pressure and reset.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
Yes
Continuity between
terminals 107 and 108?
Airflow switch (PS2) holding for proper airflow.
Correct airflow across burner.
Yes
Reference: Start-Up - Direct Gas,
Check the Optional High and Low Gas Pressure Switches, pg. 15
At this time the heater should attempt to light.
The pilot light on the flame safeguard should illuminate.
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Troubleshooting
Heater Does Not Operate (Pilot Ignition)
Attempts to light, but no pilot (visible spark)
Check inlet gas pressure.
Reference: Start-Up - Direct Gas,
Check the Supply Gas Pressure, pg. 27
Note: The minimum and maximum gas pressures
for your unit are shown on the direct gas label.
Reference: Start-Up - Direct Gas, Check the Supply Gas Pressure, pg. 27
Yes
Gas pressure between the
minimum and maximum shown
No
on the direct gas label?
Correct gas pressure.
Reference: Start-Up - Direct Gas, Check the Supply Gas Pressure, pg. 27
Yes
Air in the gas line?
Purge gas line.
Verify gas at the pilot.
No
Check for proper airflow.
Reference: Start-Up-Direct Gas,
Set the Burner Air Pressure Differential, pg.16
Note: The airflow may satisfy the airflow switch, but may
make lighting the pilot difficult. Adjust the pressure drop
across the burner between 0.625 and 0.675 in. WC
Reference: Start-Up-Direct Gas,
Yes
Set the Burner Air Pressure Differential, pg. 16
Pressure drop across the burner
between 0.625 and 0.675 in. WC?
No
Adjust burner baffles.
Reference: Start-Up-Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
Yes
Crossed flame and spark wires.
Uncross wires and reconnect.
Incorrect spark plug gap.
Set spark plug gap to 0.062 inches.
Defective spark plug.
No
Proper spark?
Yes
Replace spark plug.
Check for proper pilot pressure.
Reference: Start-Up - Direct Gas,
Check the Pilot Gas Pressure, pg. 15
Note: A high pilot pressure will make lighting more difficult.
Lower the pilot pressure in increments until the unit lights.
Then set the pilot per the instruction.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
No
No
Pilot pressure correct?
Adjust the pilot pressure.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
Yes
With proper airflow, gas pressure and spark,
the unit should light.
If problems remain, consult the factory.
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Troubleshooting
Heater Does Not Operate (Pilot Ignition)
Visible pilot
Measure the flame signal
when there is a visible pilot
Note: The flame signal should be steady and
above 1.25 VDC with a visible pilot.
Reference: Start-Up - Direct Gas,
Flame Signal Check - Pilot Ignition, pg. 18
Flame signal greater
than 1.25 VDC
No
Unit is not grounded.
Properly ground unit.
Flame rod is grounding out.
Adjust the flame rod to avoid contact with the burner or the unit.
Cracked porcelain on flame rod.
Replace flame rod.
Yes
Check for proper airflow
Reference: Start-Up-Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
Note: When the pressure is low or marginal and the unit
begins heating, the air density will change. This can cause the
pressure to drop below the minimum setting. Also, low airflow
can cause the flame to walk out of the burner and away from
the flame sensor, causing the unit to recycle.
Pressure drop across the burner
between 0.625 and 0.675 in. WC?
No
Adjust burner baffles
Reference: Start-Up-Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
Yes
Check the minimum firing rate
Reference: Start-Up - Direct Gas,
Set the Unit’s Operating Temperature, pg. 18
Note: Burners greater than 36 inches in length use an
interrupted pilot. The pilot is turned off 10 seconds after
lighting the main burner and the flame safeguard monitors the
main flame instead of the pilot flame. If the minimum fire is set
too low, the flame safeguard may not be able to sense it.
No
No
Is the minimum firing rate
set correctly?
Adjust the minimum firing rate.
Reference: Start-Up - Direct Gas,
Set the Unit’s Operating Temperature, pg. 18
Yes
Does the flame signal
remain constant?
If the signal slowly drops off, typically the airflow is too low.
Reference: Start-Up - Blowers, Set the Maximum Firing Rate
If it suddenly drops to zero, the flame rod is grounding out.
Adjust the flame rod to avoid contact with the burner or the unit.
Yes
If the flame signal is above 1.25 VDC and constant,
the main gas valves will remain open until the call
for heat is interrupted or the unit is shut down.
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Troubleshooting
Heater Does Not Operate (Direct Spark)
Does not attempt to light (No visible spark)
No
No
No
No
No
No
24 VAC between
terminals W1 and X?
Heat switch (S4) off.
Turn heat switch (S4) on.
Heat switch not wired.
Wire heat switch (S4).
Yes
24 VAC between
terminals 22 and 21?
Main transformer (TR2) defective.
Yes
Replace transformer.
24 VAC between
terminals 23 and 21?
(Optional) inlet air sensor (TS4) holding.
Adjust TS4 setting.
Reference: Start-Up - Blower, Set-Up Optional Components, pg. 15
Heat relay (RH) defective.
Yes
Replace heat relay (RH).
24 VAC between
terminals 24 and 21?
High limit (HLC1) tripped.
Reset, replace high limit (HLC1).
Check on cause of control loss.
Yes
24 VAC between
terminals 26 and 21?
(Optional) high/low gas pressure switch(es)
(PS3 and PS4) tripped.
Correct gas pressure and reset.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
Yes
Continuity between
terminals 26 and 27?
Airflow switch (PS2) holding for proper airflow.
Correct airflow across burner.
Yes
Reference: Start-Up - Direct Gas,
Check the Optional High and Low Gas Pressure Switches, pg. 15
At this time the heater should attempt to light.
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Troubleshooting
Heater Does Not Operate (Direct Spark)
Attempts to light, but no flame (Visible spark)
Is the low fire set properly?
Reference: Start-Up - Direct Gas,
Set the Minimum Firing Rate, pg. 17
No
Adjust the low fire setting.
Reference: Start-Up - Direct Gas,
Set the Minimum Firing Rate, pg. 17
Yes
Check inlet gas pressure.
Reference: Start-Up - Direct Gas,
Check the Supply Gas Pressure, pg. 15
Gas pressure between the
minimum and maximum shown
on the direct gas label?
No
Correct gas pressure.
Reference: Start-Up - Direct Gas,
Check the Supply Gas Pressure, pg. 15
Yes
Yes
Air in the gas line?
Purge gas line.
No
Check burner pressure drop
Reference: Start-Up - Direct Gas, Check the
Optional High and Low Pressure Switches, pg. 15
No
No
Pressure drop across the burner
between 0.625 and 0.675 in. WC?
Adjust burner baffles.
Reference: Start-Up - Direct Gas,
Check the Optional High and Low Gas Pressure Switches, pg. 15
Yes
Crossed flame and spark wires.
Uncross wires and reconnect.
Incorrect spark plug gap.
Set spark plug gap to 0.062 in.
Defective spark plug.
Proper spark?
Replace spark plug.
Yes
With proper airflow, gas pressure and spark,
the unit should light.
If problems remain, consult the factory.
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Maintenance - Routine
Motors
CAUTION
Motor maintenance is generally limited to cleaning and
lubrication (where applicable).
Lock-out the gas and the electrical power to the
unit before performing any maintenance or service
operations to this unit.
Cleaning should be limited to exterior surfaces only.
Removing dust and grease build-up on the motor
assures proper motor cooling.
V-Belt Drives
V-belt drives must be checked on a regular basis for
wear, tension, alignment, and dirt accumulation.
Motors supplied with grease fittings should be
greased in accordance with the manufacturer’s
recommendations.
Check the tension by measuring the deflection in the
belt as shown below.
IMPORTANT
Check the alignment by using a straight edge across
both sheaves as shown below.
Do not allow water or solvents to enter the motor
or bearings. Motors and bearings should never be
sprayed with steam, water or solvents.
IMPORTANT
IMPORTANT
Premature or frequent belt failures can be caused by
improper belt tension or misaligned sheaves.
• Abnormally high belt tension or drive misalignment
will cause excessive bearing loads and may result in
failure of the fan and/or motor bearings.
Greasing motors is only intended when fittings are
provided. Many motors are permanently lubricated,
requiring no additional lubrication.
• Abnormally low belt tension will cause squealing on
start-up, excessive belt flutter, slippage, and
overheated sheaves.
Wheels
Wheels require little attention when moving clean air.
Occasionally oil and dust may accumulate on the wheel
causing imbalance. When this occurs the wheel and
housing should be cleaned to assure proper operation.
IMPORTANT
Do not pry belts on or off the sheave. Loosen belt
tension until belts can be removed by simply lifting the
belts off the sheaves.
Filters
IMPORTANT
Filter maintenance is generally limited to cleaning and
replacement.
When replacing V-belts on multiple groove drives,
all belts should be changed to provide uniform drive
loading.
Aluminum mesh filters can be washed in warm soapy
water.
IMPORTANT
An adhesive spray can be added to aluminum mesh
filters to increase their efficiency.
Do not install new belts on worn sheaves. If the
sheaves have grooves worn in them, they must be
replaced before new belts are installed.
IMPORTANT
When reinstalling filters, be sure to install them with
the airflow in the correct direction. An airflow direction
arrow is located on the side of the filters.
Belt Span
Deflection =
64
IMPORTANT
Replacement filters should be from the same
manufacturer and the same size as the original filters
provided with the unit.
Belt Span
Belt Tension
Drive Alignment
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Bearings
Maintenance - Fall
The bearings for the fans are carefully selected to
match the maximum load and operating conditions
of the specific class, arrangement and fan size. The
instructions provided in this manual and those provided
by the bearing manufacturer will minimize any bearing
problems.
Start-Up
Repeat the information as outlined in:
• Start-Up - Blower (page 14)
- Air Volume Measurement and Check
• Start-Up - Direct Gas (pages 15 and 16)
- Check the Supply Gas Pressure
- Check the Pilot Gas Pressure
IMPORTANT
Lubricate bearings prior to periods of extended
shutdowns or storage and rotate shaft monthly to aid
in corrosion prevention. If the fan is stored more than
three months, purge the bearings with new grease
prior to start-up.
- Check the Optional High and Low Gas Pressure
Switches
- Set the Burner Air Pressure Differential
This will ensure that the gas and air are set properly
before the heating season begins and should lead to
trouble free operation all winter.
Recommended Bearing Lubrication Schedule (in Months*)
Bearing Bore Size (inches)
Fan
High Limit
The high limit switch may have tripped over the
1
⁄2
-1
11⁄8 -11⁄2
15⁄8 -17⁄8 115⁄16 -23⁄16
27⁄16 -3
RPM
summer; it should be checked and reset if necessary.
750
6
5
4
3
3
*Suggested initial greasing interval is based on 12 hour per
day operation and 150°F maximum housing temperature.
For continuous (24 hour) operation, decrease greasing
interval by 50%
Burner
Inspect the burner for accumulation of scales on both
the upstream and downstream sides of the mixing
plates. Any scaling or foreign material should be
removed with a wire brush.
• If extended grease lines are present, relubricate while in
operation, only without endangering personnel.
• For ball bearings (operating) relubricate until clean grease is
seen purging at the seals. Be sure not to unseat the seal by
over lubricating.
• For ball bearings (idle) add 1-2 shots of grease up to 2 in.
bore size, and 4-5 shots above 2 in. bore sizes with a hand
grease gun.
• For roller bearings add 4 shots of grease up to 2 in. bore
size, and 8 shots for 2-5 in. bore size with a hand grease
gun.
Visually check that all holes in the mixing plates are
clear. If any burner ports are plugged (even partially),
clear them with a piece of wire or another appropriate
tool.
Replace or tighten any loose or missing fasteners on the
mixing plates. Always use zinc-plated or stainless steel
fasteners.
Inspect and clean the flame and spark rod. Occasional
replacement of the flame rod and spark rod may be
necessary to ensure optimum unit performance.
• Adjust re lubrication frequency based on condition of
purged grease.
• A high quality lithium based grease conforming to NLGI
Grade 2 consistency, such as those listed here:
WARNING
Mobil 532
Texaco Multifak #2
B Shell Alavania #2
Mobilux #2
Texaco Premium #2 Exxon Unirex #2
Do not enlarge burner ports when clearing a blockage,
performance could be affected.
NOTE
Flame rods can last many years, but because of
thermal expansion of the porcelain, flame rods can fail
over time.
Gas Train
The gas connections, joints and valves should be
checked annually for tightness. Apply a soap and water
solution to all piping; watch for bubbling which indicates
a leak. Other leak testing methods can be used.
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Reference
Typical Gas Train Layout with Modulating Valve (Pilot Ignition)
Pilot
Solenoid
Pilot
Regulator
Burner Differential
Pressure Sensor
Pilot Gas Pressure
Test Port
Modulating
Valve
Low Gas
Pressure Switch
(optional)
Manual Pilot
Shut-Off Valve
High Gas
Pressure Switch
(optional)
Burner Manual
Shut-Off Valve
Safety Shut-Off
Valves
Regulator
Burner Gas
Pressure
Test Port
Typical Gas Train Layout with Modulating Regulator (Pilot Ignition)
Pilot
Solenoid
Pilot
Regulator
Burner Differential
Pressure Sensor
Pilot Gas Pressure
Test Port
Low Gas
Pressure Switch
(optional)
Modulating/Regulator
Valve
Manual Pilot
Shut-Off Valve
High Gas
Pressure Switch
(optional)
Burner Manual
Shut-Off Valve
Safety Shut-Off
Valves
Burner Gas
Pressure
Test Port
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Reference
Typical Gas Train Layout with Direct Spark Ignition
This is a typical gas train. The gas train in your unit may be different.
Burner Differential
Pressure Sensor
(Airflow Switch)
To Burner
High Gas
Pressure
Switch
Combination
(Optional)
Low Gas
Pressure Switch
(Optional)
Modulating
Shut-Off Valve/
Valve
Regulator
Low Gas
Pressure
Test Port
Burner Manual
Shut-Off Valve
High Gas
Pressure
Test Port
Gas
Connection
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Reference
Control Center Layout
6
10
11
24
25
13
22
12
27
26
28
14
19
20
3
18
4
1
7
8
15
2
9
21
17
1. Supply Motor Starter — 24 volt magnetic
contacts for starting supply motor.
2. Supply Overload — provides electronic overload
18. Flame Safeguard/Spark Generator (Direct
Spark) — monitors flame, shuts down unit when
unsafe conditions are detected.
protection to supply motor.
19. High Limit — prevents unit from discharging air
above a set point.
3. Low Voltage Transformer — provides low
voltage to fan/heat/cooling enable controls.
20. Low Voltage Transformer — reduces voltage to
Maxitrol system.
4. Control Terminal Block — provides wiring
access to controls.
21. Amplifier — controls modulating valve, assures
the desired temperature is delivered.
5. Fan Relay — allows power to pass to energize
motor starter.
22. Transformer (optional) — provides voltage to
optional evaporative cooling pump.
6. High Voltage Enclosure — provides protection
from high voltage circuits.
23. Cooling Relay (optional) — allows power to
pass to cooling controls.
24. Cooling Terminal Block (optional) — provides
7. Auxiliary Contact (optional) — provides one
normally closed and one normally open contact for
other equipment.
wiring access to cooling controls.
8. Exhaust Motor Starter (optional) — 24 volt
25. Low Voltage Transformer (optional) — reduces
magnetic contacts for starting exhaust motor.
voltage to cooling controls.
9. Exhaust Overload (optional) — provides
26. Reset Timer (optional) — resets cooling system
electronic overload protection to exhaust motor.
to run a time interval.
10. Transformer Fuse (optional) — provides proper
fusing for cooling transformer.
11. Terminal Block — provides wiring access to high
27. Auto Drain Relay (optional) — assures supply
pump does not operate during drain interval.
Allows pump to operate in cooling mode.
voltage circuits.
12. Exhaust Fuses (optional) — provides proper
28. Cooling Timer (optional) — allows for automatic
draining of the evaporative cooling system based
on time schedule.
fusing for exhaust fan motor(s).
13. Dirty Filter Switch (optional) — monitors filter
pressure drop, turns on indicating light when
pressure drop is above field adjustable set point.
Dirty Filter Switch
Common
14. Inlet Air Sensor (optional) — outdoor air stat
that automatically controls the heating and/or
cooling based on outdoor air temperature.
Normally Open
Normally Closed
CCW to Decrease Trip Point
CW to Increase Trip Point
15. Remote Temperature Selector (optional) —
allows for remote temperature set point.
Negative Pressure
after the filters
16. Heat Relay — allows power to pass to heating
controls.
Positive Pressure
before the filters
17. Heating Terminal Block — provides wiring
access to heating controls.
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Maintenance Log
Date ___________________Time _____________ AM/PM
Notes:___________________________________________
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_________________________________________________
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Date ___________________Time _____________ AM/PM
Notes:___________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
Date ___________________Time _____________ AM/PM
Notes:___________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
Date ___________________Time _____________ AM/PM
Notes:___________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
Date ___________________Time _____________ AM/PM
Notes:___________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
Date ___________________Time _____________ AM/PM
Notes:___________________________________________
_________________________________________________
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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 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’s Model VSU 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
®
Phone: (715) 359-6171 • Fax: (715) 355-2399 • E-mail: [email protected] • Web site: www.greenheck.com
470654 • Model VSU IOM, Rev. 1, March 2012
Copyright 2012 © Greenheck Fan Corporation
36
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