Greenheck 470654 User Manual
Document 470654
VSU Make-Up Air Unit
®
®
Installation, Operation and Maintenance Manual
Installation, Operation and Maintenance Manual
Please read and save these instructions. Read carefully before attempting to assemble, install, operate or maintain the
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
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.
result in personal injury and/or property damage! Retain instructions for future reference.
with Direct-Fired Gas Heater
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.
General Safety Information
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.
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.
2. The rotation of the wheel is critical. It must be free
to rotate without striking or rubbing any stationary
objects.
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.
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.
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.
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.
Model VSU Make-Up Air Unit
1
Receiving
Upon receiving the product check to make sure all items
are accounted for by referencing the bill of lading to
ensure all items were received. Inspect each crate for
shipping damage before accepting delivery. Notify the
carrier if any damage is noticed. The carrier will make
notification on the delivery receipt acknowledging any
damage to the product. All damage should be noted on
all the copies of the bill of lading which is countersigned
by the delivering carrier. A Carrier Inspection Report
should be filled out by the carrier upon arrival and
reported to the Traffic Department. If damaged upon
arrival, file claim with carrier. Any physical damage to
the unit after acceptance is not the responsibility of
Greenheck Fan Corporation.
Unpacking
Verify that all required parts and the correct quantity
of each item have been received. If any items are
missing, report shortages to your local representative to
arrange for obtaining missing parts. Sometimes it is not
possible that all items for the unit be shipped together
due to availability of transportation and truck space.
Confirmation of shipment(s) must be limited to only
items on the bill of lading.
Handling
Units are to be rigged and moved by the lifting brackets
provided or by the skid when a forklift is used. Location
of brackets varies by model and size. Handle in such
a manner as to keep from scratching or chipping the
coating. Damaged finish may reduce ability of unit to
resist corrosion.
Storage
Units are protected against damage during shipment. If
the unit cannot be installed and operated immediately,
precautions need to be taken to prevent deterioration of
the unit during storage. The user assumes responsibility
of the unit and accessories while in storage. The
manufacturer will not be responsible for damage during
storage. These suggestions are provided solely as a
convenience to the user.
Inspection and Maintenance during Storage
While in storage, inspect fans once per month. Keep a
record of inspection and maintenance performed.
If moisture or dirt accumulations are found on parts,
the source should be located and eliminated. At each
inspection, rotate the fan wheel by hand ten to fifteen
revolutions to distribute lubricant on motor. Every three
months, the fan motor should be energized. If paint
deterioration begins, consideration should be given to
touch-up or repainting. Fans with special coatings may
require special techniques for touch-up or repair.
Machined parts coated with rust preventive should be
restored to good condition promptly if signs of rust
occur. Immediately remove the original rust preventive
coating with petroleum solvent and clean with lint-free
cloths. Polish any remaining rust from surface with
crocus cloth or fine emery paper and oil. Do not destroy
the continuity of the surfaces. Wipe thoroughly clean
with Tectyl
®
506 (Ashland Inc.) or the equivalent. For
hard to reach internal surfaces or for occasional use,
consider using Tectyl
®
511M Rust Preventive or WD-40®
or the equivalent.
REMOVING FROM STORAGE — As units are removed
from storage to be installed in their final location, they
should be protected and maintained in a similar fashion,
until the equipment goes into operation.
Prior to installing the unit and system components,
inspect the unit assembly to make sure it is in working
order.
1. Check all fasteners, set screws on the fan, wheel,
bearings, drive, motor base, and accessories for
tightness.
2. Rotate the fan wheel(s) by hand and assure no parts
are rubbing.
OUTDOOR — Units designed for outdoor applications
may be stored outdoors, if absolutely necessary. Roads
or aisles for portable cranes and hauling equipment are
needed.
The fan should be placed on a level surface to prevent
water from leaking into the unit. The unit should be
elevated on an adequate number of wooden blocks so
that it is above water and snow levels and has enough
blocking to prevent it from settling into soft ground.
Locate parts far enough apart to permit air circulation,
sunlight, and space for periodic inspection. To minimize
water accumulation, place all unit parts on blocking
supports so that rain water will run off.
Do not cover parts with plastic film or tarps as these
cause condensation of moisture from the air passing
through heating and cooling cycles.
Model VSU Make-Up Air
2
®
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
Our commitment
.....................Backcover
®
Model VSU Make-Up Air
3
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.
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.
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
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.
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.
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 2in.
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’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.
Optional Service Platform
A service platform
is available
for permanent
attachment to the
mounting stand.
The platform
is shipped
unassembled
and requires
field assembly.
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. Ladders
are not provided by factory.
Model VSU Make-Up Air
4
®
Burner, Blower and Control Center Section
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.
The blower section of the unit consists of one motor and
either one or two forward curved blowers. It is the topmost 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).
Blowers
Control Center/
Gas Train
Filters
Burner
Open View
®
Model VSU Make-Up Air
5
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.
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
Optional Motorized
Recirculating 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.
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.
Passive Control Damper
Optional Motorized
Intake Damper
Manual High Voltage
On/Off Switch
with Lockout
Model VSU Make-Up Air
6
®
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.
Concrete Slab Dimensions
Housing Size A B C D E
20 64 64 42 37 37
30 77 76 42 49 49
40 78 135 42 51 108
50 87 180 42 60 153
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
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
A
12
D
E
12
B
Concrete Slab and Unit Footprint
Unit Control Side
Required with service
platform only
C
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.
Clearance to Combustibles
Floor Top Sides Ends
Insulated/
Units
Non Insulated
Units
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.
0 in.
(0 mm)
0 in.
(0 mm)
0 in.
(0 mm)
6 in.
(152.4 mm)
0 in.
(0 mm)
6 in.
(152.4 mm)
0 in.
(0 mm)
6 in.
(152.4 mm)
Install Ductwork
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.
Recommended Supply Ductwork Sizes
VSU
Blower Size
108 10x13 32
109 14x13 38
110 16x14 42
112 18x16 48
115 19x16 49
118 24x22 64
120 28x28 79
218 68x24 114
220 68x26 118
225 104x37 175
230 104x37 203
Duct Size
(in.)
Straight Duct Length
(in.)
®
Model VSU Make-Up Air
7
Complete Installation
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.
Installation of Optional Service Platform
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
Safety Chains
(1) Platform Base Unit with
predrilled holes for hand
rails, legs and attachments.
Fasteners
(3)
(2)
(18)
(1) Right Hand Rail
Hex Head Bolts
3/8 in. x 1-1/2 in.
Thread Cutting
Screws
3/8 in. x 1 in.
Hex Head Bolts
3/8 in. x 3/4 in.
(2) Legs
(1) Leg Cross Member
Model VSU Make-Up Air
8
(27)
Hex Head Nuts
3/8 in.
®
Assembly
1. Position platform base as shown below in FigureA
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. Raise the platform base, grate side up, with a crane
or forklift.
4. Attach legs to the slots on sides of platform base
with two (3/8 in. x 3/4 in.) hex head bolts and
(3/8in.) hex nuts.
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 FigureC.
3/8 inch
Form Line
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
1-1/2in.) 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.
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
Figure B
to the unit.
®
Attachment Points
for Step 11
Figure D
Model VSU Make-Up Air
9
Installation of Electrical Wiring
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).
IMPORTANT
All wiring should be done in accordance with the
latest edition of the National Electric Code ANSI/
NFPA70 and any local codes that may apply. In
Canada, wiring should be done in accordance with
the Canadian Electrical Code.
IMPORTANT
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.
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.
DANGER
High voltage electrical input is needed for this
equipment. This work should be performed by a
qualified electrician.
CAUTION
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.
IMPORTANT
Manufacturer’s standard control voltage is 24VAC.
Control wire resistance should not exceed 0.75ohms
(approximately 285 feet total length for 14gauge
wire; 455 feet total length for 12gauge 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.
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
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.
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.
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.
Wire the Optional Accessories
Reference the ladder diagram on the inside of the
control center door for correct wiring of the following
accessories:
• Selectra Stat • Indicating Lights
• Room Override • Dirty Filter Indicator
• Blower Switch • TSCP
• Heat Switch • KSCP
NOTE
Wiring to the Selectra Stat should be in separate
conduit or run with shielded cable.
NOTE
TSCP has number-to-number wiring.
NOTE
Large evaporative coolers may require a separate
power supply.
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.
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 industrialstyle, 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.
Model VSU Make-Up Air
10
®
Installation of Direct Gas Piping
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.
WARNING
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.
WARNING
If pressure testing in excess of 1/2 psig (3.5kPa), the
heater and manual shutoff valve must be disconnected
from the supply gas line.
WARNING
If pressure testing at or below 1/2 psig (3.5kPa), the
heater must be isolated from the supply gas line by
closing its manual shutoff valve.
IMPORTANT
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
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.
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
MAX BTU/HR
BTU/H MAX
NORMAL MANIFOLD
PRESSURE
PRESSION DÕADMISSION
NORMALE
MIN GAS
PRESSURE
PRESSION DE GAZ
MIN BURNER
PRESSURE DROP
PERTE MIN DE PRESSION
DANS LE BRULEUR
TYPE OF GAS
NATURE DU GAZ
EQUIPPED FOR
CONCU POUR
Type of gas
AGAINST
SCFM
CONTE
Direct Gas Nameplate
MIN BTU/HR
BTU/H MIN
MIN GAS PRESSURE
FOR MAX OUTPUT
“ WC
PRESSION DE GAZ MIN
POUR PUISSANCE MAX
MAX GAS
PRESSURE
“ WC
PRESSION DE GAZ
MAX
MAX BURNER
PRESSURE DROP
“ WC
PERTE MAX DE PRESSION
DANS LE BRULEUR
DESIGN ΔT
ΔT NORMALE
“ WC
Maximum gas pressure
“ WC
“ WC
PSI
F
EXTERNAL STATIC PRESSURE
PRESSION STATIQUE EXTERIEURE
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.
NOTE
The regulator located inside the unit is used to adjust
the unit’s maximum output temperature.
®
Model VSU Make-Up Air
11
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