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Questions?
Help is just a moment away!
Call: Home Generator Helpline
(877) 369-9400 M-F 8-5 CT
Manual No. 202113GS Rev. - (01/03/07)
12000 / 15000 Watt
Residential Generator
System
Installation and Start-Up Manual
GEN12S, GEN15S, GEN20B & GEN25B
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Thank you for purchasing this quality-built Rheem / Ruud home standby generator. We are pleased that you’ve placed your
confidence in the Rheem or Ruud brand. When operated and maintained according to the instructions in this manual, your
Rheem / Ruud generator will provide many years of dependable service.
This manual contains safety information to make you aware of the hazards and risks associated with installing residential
standby generators and how to avoid them. Because Rheem does not necessarily know all the applications this equipment
could be used for, it is important that you read and understand these instructions thoroughly before attempting to install or
start this equipment. Save these instructions for future reference.
This home standby generator requires professional installation before use. The installer should follow the instructions
completely.
Where to Find Us
You never have to look far to find support and service for your home standby generator equipment. Consult your Yellow
Pages. There are many Rheem and Ruud authorized service dealers who provide quality service. You can also contact
Rheem/Ruud Customer Service by phone at (877) 369-9400.
Rheem Sales Company
Randleman, NC 27317
(877) 369-9400
Copyright © 2007 Rheem Sales Company. All rights
reserved. No part of this material may be reproduced or
transmitted in any form by any means without the express
written permission of Rheem Sales Company.
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Table of Contents
Important Safety Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Equipment Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Customer Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Installer Responsibilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Unpacking Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Delivery Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Shipment Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Required Specialty Tools/Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Generator Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Fuel and Electrical Inlet Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Lifting the Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Access Doors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
The Gaseous Fuel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Fuel Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Fuel Pipe Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Fuel Comparison Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
System Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
System AC Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Grounding the Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Utility Circuit Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Fault Detection System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
System Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Before Initial Start-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Fuel System Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Initial Start-Up (No Load) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Engine Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Setting Exercise Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Installation Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Schematic and Wiring Diagram for Models GEN12S and GEN20B . . . . . . 20
Schematic and Wiring Diagram for Models GEN15S and GEN25B . . . . . . 21
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Important Safety Rules
The safety alert symbol ( ) is used with a signal word
(DANGER, CAUTION, WARNING), a pictorial and/or a safety
message to alert you to hazards. DANGER indicates a hazard
which, if not avoided, will result in death or serious injury.
WARNING indicates a hazard which, if not avoided, could
result in death or serious injury. CAUTION indicates a hazard
which, if not avoided, might result in minor or moderate
injury. NOTICE indicates a situation that could result in
equipment damage. Follow safety messages to avoid or
reduce the risk of injury or death.
Hazard Symbols and Meanings
Save These Instructions
Explosion
Fire
Electrical Shock
Rotating Parts
Hot Surface
Toxic Fumes
Chemical BurnExplosive PressureAuto Start
Lift Hazard
Read Manual
• Operate generator ONLY outdoors.
• Install a battery operated carbon monoxide alarm near the
bedrooms.
• Keep exhaust gas from entering a confined area through
windows, doors, ventilation intakes, or other openings.
WARNING
Running engine gives off carbon monoxide, an
odorless, colorless, poison gas.
Breathing carbon monoxide can cause headache,
fatigue, dizziness, vomiting, confusion, seizures,
nausea, fainting or death.
WARNING
The engine exhaust from this product contains chemicals
known to the State of California to cause cancer, birth
defects, or other reproductive harm.
• DO NOT dispose of battery in a fire.
• Do not allow any open flame, spark, heat, or lit cigarette during
and for several minutes after charging a battery.
• DO NOT open or mutilate the battery.
• Wear protective goggles, rubber apron, and rubber gloves.
• Remove watches, rings, or other metal objects.
• Use tools with insulated handles.
WARNING
Storage batteries give off explosive hydrogen gas
during recharging.
Slightest spark will ignite hydrogen and cause
explosion.
Battery electrolyte fluid contains acid and is
extremely caustic.
Contact with battery contents will cause severe
chemical burns.
A battery presents a risk of electrical shock and
high short circuit current.
• If lifting or hoisting equipment is used, DO NOT contact any
power lines.
• DO NOT lift or move generator without assistance.
• Use lifting pipes as described in the section “Lifting the
Generator” in installation manual.
• The unit may shift on the lifting pipes during movement, which
can cause injury.
• DO NOT lift unit by roof as damage to generator will occur.
WARNING
Hazardous Voltage
Contact with power lines can cause electric shock
or burn.
Lifting Hazard / Heavy Object
Can cause muscle strain or back injury.
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• When using generator for backup power, notify utility company.
• Do not touch bare wires or receptacles.
• Do not use generator with electrical cords which are worn,
frayed, bare or otherwise damaged.
• Do not handle generator or electrical cords while standing in
water, while barefoot, or while hands or feet are wet.
• If you must work around a unit while it is operating, stand on an
insulated dry surface to reduce shock hazard.
• Do not allow unqualified persons or children to operate or
service generator.
• In case of an accident caused by electrical shock, immediately
shut down the source of electrical power and contact the local
authorities. Avoid direct contact with the victim.
• Despite the safe design of the generator system, operating this
equipment imprudently, neglecting its maintenance or being
careless can cause possible injury or death.
• Remain alert at all times while working on this equipment. Never
work on the equipment when you are physically or mentally
fatigued.
• Before performing any maintenance on the generator, disconnect
the battery cable indicated by a NEGATIVE, NEG or (-) first.
When finished, reconnect that cable last.
• After your generator system is installed, the generator may crank
and start without warning any time there is a power failure. To
prevent possible injury, always set the generator’s system switch
to OFF, remove the service disconnect from the disconnect box
AND remove the 15 Amp fuse BEFORE working on the
equipment.
WARNING
Generator produces hazardous voltage.
Failure to properly ground generator can result in
electrocution.
Failure to isolate generator from power utility can
result in death or injury to electric utility workers
due to backfeed of electrical energy.
• DO NOT touch hot parts and AVOID hot exhaust gases.
• Allow equipment to cool before touching.
• DO NOT install the generator closer than 5 feet (1.5m) from any
combustibles or structures with combustible walls having a fire
resistance rating of less than 1 hour.
• Keep at least 3 ft. (91 cm) clearance on all sides of generator
including overhead.
• Code of Federal Regulation (CFR) Title 36 Parks, Forests, and
Public Property require equipment powered by an internal
combustion engine to have a spark arrester, maintained in
effective working order, complying to USDA Forest service
standard 5100-1C or later revision. In the State of California a
spark arrester is required under section 4442 of the California
Public resources code. Other states may have similar laws.
WARNING
Contact with muffler area can result in serious
burns.
Exhaust heat/gases can ignite combustibles or
structures causing a fire.
• Install the fuel supply system according to applicable fuel-gas
codes.
• Before placing the generator system into service, the fuel system
lines must be properly purged and leak tested.
• After the generator is installed, you should inspect the fuel
system periodically.
• NO leakage is permitted.
• DO NOT operate engine if smell of fuel is present or other
explosive conditions exist.
• DO NOT smoke around the generator. Wipe up any oil spills
immediately. Ensure that no combustible materials are left in the
generator compartment. Keep the area near the generator clean
and free of debris.
WARNING
Propane and Natural Gas are extremely flammable
and explosive.
Fire or explosion can cause severe burns or
death.
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• Use generator only for intended uses.
• If you have questions about intended use, ask dealer or contact
Rheem.
• Operate generator only on level surfaces.
• Adequate, unobstructed flow of cooling and ventilating air is
critical to correct generator operation.
• The Oil Fill, Oil Drain and the Control Panel doors must be
installed whenever the unit is running.
• DO NOT expose generator to excessive moisture, dust, dirt, or
corrosive vapors.
• Despite the safe design of the residential generator system,
operating this equipment imprudently, neglecting its maintenance
or being careless can cause possible injury or death.
• Remain alert at all times while working on this equipment.
NEVER work on the equipment when you are physically or
mentally fatigued.
• DO NOT start engine with air cleaner or air cleaner cover
removed.
• DO NOT insert any objects through cooling slots.
• DO NOT use the generator or any of its parts as a step. Stepping
on the unit can cause stress and break parts. This may result in
dangerous operating conditions from leaking exhaust gases, fuel
leakage, oil leakage, etc..
• If connected devices overheat, turn them off and disconnect
them from generator.
• Shut off generator if:
-electrical output is lost;
-equipment sparks, smokes, or emits flames;
-unit vibrates excessively.
NOTICE
Improper treatment of generator can damage it and shorten
its life.
• See “Essential Circuits”.
• Start generator and let engine stabilize before connecting
electrical loads.
NOTICE
Exceeding generators wattage/amperage capacity can
damage generator and/or electrical devices connected to it.
• Observe that the 15 Amp fuse has been removed from the
control panel for shipping.
• DO NOT install this fuse until all plumbing and wiring has been
completed and inspected.
CAUTION
Installing the 15A fuse could cause the engine to
start.
• DO NOT tamper with governed speed. Generator supplies correct
rated frequency and voltage when running at governed speed.
• DO NOT modify generator in any way.
CAUTION
Excessively high operating speeds increase risk of injury
and damage to generator.
Excessively low speeds impose a heavy load.
• NEVER operate generator without protective housing or covers.
• DO NOT wear loose clothing, jewelry or anything that may be
caught in the starter or other rotating parts.
• Tie up long hair and remove jewelry.
WARNING
Starter and other rotating parts can entangle
hands, hair, clothing, or accessories.
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Installation
Equipment Description
This system is intended for use as an optional residential
generator system which provides an alternate source of
electric power and to serve loads such as heating,
refrigeration systems, and communication systems that,
when stopped during any power outage, could cause
discomfort, or the like. This product does not qualify for
emergency standby as defined by NFPA 70 (NEC).
This manual contains installation, startup and adjustment
instructions for a residential generator system that supplies
120/240 Volt, single phase, 60Hz devices. The generator
system may be operated on LP or natural gas fuel. A
separate Operator’s Manual (part number 202114GS)
contains operating and maintenance instructions for this
system.
Every effort has been made to ensure that the information in
this manual is both accurate and current. However, the
manufacturer reserves the right to change, alter or otherwise
improve the system at any time without prior notice.
Customer Responsibilities
• Read and follow the instructions given in the Operator’s
Manual, especially the section regarding selecting
essential circuits.
• Follow a regular schedule in maintaining, caring for and
using your generator system, as specified in the
Operator’s Manual.
Installer Responsibilities
• Read and observe the safety rules.
• Read and follow the instructions given in this
Installation and Start-up Manual.
• If operating the generator below 40°F, it is
recommended that a battery and oil warmer be
installed. If operating the generator below 32°F, a
battery and oil warmer must be installed. Both items
are available at your local servicing dealer.
IMPORTANT: DO NOT OVERLOAD GENERATOR. Refer to
Essential Circuits in the Operator’s Manual and discuss
your installation plan with the owner before commencing
work.
Unpacking Precautions
The unit is shipped bolted to its mounting pad, ready for
installation. Avoid damage from dropping, bumping,
collision, etc. Store and unpack carton with the proper side
up, as noted on the shipping carton.
Delivery Inspection
After removing the carton, carefully inspect the generator
system for any damage that may have occurred during
shipment.
IMPORTANT: If loss or damage is noted at time of delivery,
have the person(s) making delivery note all damage on the
freight bill and affix his signature under the consignor's
memo of loss or damage. If loss or damage is noted after
delivery, separate the damaged materials and contact the
carrier for claim procedures. Missing or damaged parts are
not warranted.
Shipment Contents
The generator system is supplied with:
• Residential Generator System
• Pre-attached mounting pad
• One flexible hook-up hose
• This installation and start-up manual
• Operator’s manual
• Illustrated parts list manual
• Installation checklist
• Two access door keys
• Four lifting hole plugs
• Oil fill spout
• One spare 15A fuse
• 2 Pole connector (for 240V from building)
• 10 Pole connector (for sensing and control wires)
• Air intake engine cover
• Alternator cover
• Diagnostic LED kit (red LED/plate/screws (2))
Required Specialty Tools/Equipment
• Two 48” lengths of 1” pipe (NOT conduit)
• Hole punches for 16ga steel
• Torque screwdriver, 5 to 50 inch-pound range
• Observe that the 15 Amp fuse has been removed from the
control panel for shipping.
• DO NOT install this fuse until all plumbing and wiring has been
completed and inspected.
CAUTION
Installing the 15A fuse could cause the engine to
start.
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Generator Location
Before installing generator, consult with homeowner and
convey the following guidelines which may affect the desired
location.
Install generator outdoors in an area which will not
accumulate deadly exhaust gas. DO NOT install generator
where exhaust gas could accumulate and enter inside or be
drawn into a potentially occupied building. Ensure exhaust
gas is kept away from any windows, doors, ventilation
intakes or other openings that can allow exhaust gas to
collect in a confined area (Figure 1). Prevailing winds and air
currents should be taken into consideration when positioning
generator.
General Location Guidelines
• Install the unit outdoors ONLY.
• Place the unit in a prepared location that is flat and has
provisions for water drainage.
• Install the unit in a location where sump pump
discharge, rain gutter down spouts, roof run-off,
landscape irrigation, or water sprinklers will not flood
the unit or spray the enclosure and enter any air inlet
our outlet openings.
• Install the unit where the location of any services such
as phone, electrical, fuel, air conditioning, irrigation,
including covered, concealed and underground services
will not be affected or obstructed.
• Install the unit where air inlet and outlet openings will
not become obstructed by leaves, grass, snow, etc. If
prevailing winds will cause blowing or drifting, you may
need to construct a windbreak to protect the unit.
• Install the generator as close as possible to the Transfer
Switch to reduce the length of wiring and conduit.
• Install the generator as close as possible to the fuel
supply to reduce length of pipes.
IMPORTANT: Laws or local codes may regulate the distance
to the fuel supply.
The generator system is shipped already attached to its
mounting pad. Unless mandated by local code, a concrete
slab is not required.
If mandated by local code, construct a concrete slab at least
3 inches thick and 6 inches longer and wider than the unit.
Attach unit to slab with 1/4” diameter (minimum) masonry
anchor bolts long enough to retain the unit.
Fuel and Electrical Inlet Dimensions
Figure 2 depicts the location of the fuel piping connector.
Also shown is the recommended location for punching holes
for attaching the power conduit.
Figure 1 — Generator Location
Exhaust Port
• Operate generator ONLY outdoors.
• Install a battery operated carbon monoxide alarm near the
bedrooms.
• Keep exhaust gas from entering a confined area through
windows, doors, ventilation intakes, or other openings.
WARNING
Running engine gives off carbon monoxide, an
odorless, colorless, poison gas.
Breathing carbon monoxide can cause headache,
fatigue, dizziness, vomiting, confusion, seizures,
nausea, fainting or death.
• DO NOT install the generator closer than 5 feet (1.5m) from any
combustibles or structures with combustible walls having a fire
resistance rating of less than 1 hour.
• Keep at least 3 ft. (91 cm) clearance on all sides of generator
including overhead.
WARNING
Exhaust heat/gases can ignite combustibles or
structures causing a fire.
Page 9
Lifting the Generator
The generator weighs more than 560 pounds. Proper tools,
equipment and qualified personnel should be used in all
phases of handling and moving the generator.
Two 48” lengths of 1” pipe (supplied by the installer) are
required to lift the generator manually. Insert pipes through
the lifting holes located near the unit’s base, as shown in
Figure 3.
You may also lift the unit using a “hook and hoist” method
attached to the lifting pipes, provided that you use a
spreader bar to ensure that the chains or cables do not touch
the generator’s roof.
After unit is in place, fill the lifting holes with the supplied
lifting hole plugs.
7
• If lifting or hoisting equipment is used, DO NOT contact any
power lines.
• DO NOT lift or move generator without assistance.
• Use lifting pipes as described in the section “Lifting the
Generator” in installation manual.
• The unit may shift on the lifting pipes during movement, which
can cause injury.
• DO NOT lift unit by roof as damage to generator will occur.
WARNING
Hazardous Voltage
Contact with power lines can cause electric shock
or burn.
Lifting Hazard / Heavy Object
Can cause muscle strain or back injury.
To lift: Insert
pipe here
Installer-supplied pipe
Figure 3 — Location of Lifting Holes
Figure 2 — Generator Fuel and Conduit Attachment Locations, Oil Fill Side of Unit
3/4” NPT
Fuel Piping
Connector
Recommended Conduit
Attachment Area
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Access Doors
The generator system is equipped with an enclosure that has
three access doors (Figure 4). The doors are named for a
significant component located behind them. Starting with the
side that has the fuel connection and proceeding clockwise,
the doors are named:
• Oil Fill door
• Control Panel door
• Oil Drain door
Each generator system is equipped with two identical keys.
These keys fit the locks that secure the access doors.
To Open an Access Door:
1. Insert key into lock of access door you wish to open
and turn one quarter turn counterclockwise.
2. Grasp door’s handle and turn one quarter turn
counterclockwise to open. Remove key.
To Close an Access Door:
1. Close door and turn doors handle one quarter of a turn
clockwise.
2. Insert key into lock of access door and turn one quarter
turn clockwise. Remove key.
The Gaseous Fuel System
TO THE INSTALLER: Consult with the generator system
owner(s) and convey any technical considerations that might
affect their installation plans before applying these general
guidelines.
The following general rules apply to gaseous fuel system
piping:
• The piping should be of a material that conforms to
federal and local codes, rigidly mounted and protected
against vibration.
• Piping should be protected from physical damage
where it passes through flower beds, shrub beds, and
other cultivated areas where damage could occur.
The information provided below is to assist gaseous fuel
system technicians in planning installations. In
no way
should this information be interpreted to conflict with
applicable fuel gas codes. Consult with your local fuel
supplier or Fire Marshall if questions or problems arise.
• DO NOT touch hot parts and AVOID hot exhaust gases.
• Allow equipment to cool before touching.
WARNING
Contact with muffler area can result in serious
burns.
Oil Fill Door
Fuel Inlet
Exhaust
Port
Oil Drain
Door
Oil Fill
Door
Control Panel Door
Oil Drain Door
Exhaust Bulkhead
Figure 4 — Enclosure Access Doors
• LP gas is heavier than air and will settle in low areas.
• Natural gas is lighter than air and will collect in high areas.
• The slightest spark can ignite these fuels and cause an
explosion.
WARNING
Propane and Natural Gas are extremely flammable
and explosive.
Fire or explosion can cause severe burns or
death.
Page 11
• Install the flexible, gaseous hose (supplied) between
the generator system Fuel Inlet port and rigid piping to
prevent thermal expansion or contraction from causing
excessive stress on the piping material.
NOTE: Where local conditions include earthquake, tornado,
unstable ground, or flood hazards, special consideration
shall be given to increase strength and flexibility of piping
supports and connections.
• Piping must be of the correct size to maintain the
required supply pressures and volume flow under
varying generator load conditions with all gas
appliances connected to the fuel system turned on and
operating.
• Use an approved pipe sealant or joint compound on all
threaded fittings to reduce the possibility of leakage.
• Installed piping must be properly purged and leak
tested, in accordance with applicable codes and
standards.
Consider the following factors when planning to install the
fuel supply system:
The generator system engine is fitted with a fuel mixer
system that meets the specifications of the California Air
Resources Board for “tamper-proof” dual fuel systems. The
unit will run on natural gas or liquefied propane (LP) vapor.
• A minimum of one accessible, approved manual shutoff
valve must be installed in the fuel supply line within 6 ft
(1.8 m) of the generator system. A union or flanged
connection must be provided downstream from this
valve to permit removal of controls.
• Natural gas fuel supply pressure at the generator's fuel
inlet port should be between 5 to 7 inches of water (in.
W.C.) with the generator off and at full load with all gas
appliances turned on and operating. LP fuel supply
pressure should be 11 to 14 inches of water (in. W.C.)
with the generator off and at full load with all gas
appliances turned on and operating.
The generator system has been factory set to run on
natural gas. If you need to change from natural gas to LP
gas, the unit will need to be reconfigured, as described later
in this manual.
It is recommended that the fuel connection incorporate the
following components:
• A manual fuel shut-off valve located in the interior of
the building.
• A manual fuel shut-off valve located outside the
building, just before the generator unit.
• Where the formation of hydrates or ice is known to
occur, piping should be protected against freezing. The
termination of hard piping should include a sediment
trap where condensate is not likely to freeze.
• A manometer port should be provided.
The manometer port permits temporary installation of a
manometer (Figure 5), to ensure that the engine receives the
correct fuel pressure to operate efficiently throughout its
operating range.
When the initial test runs are completed, the manometer is
removed and the port is plugged. A typical final fuel
connection assembly is shown in Figure 6.
9
Figure 6 — Completed Fuel Connections
Figure 5 — Temporary Manometer Installed
From fuel
supply line
To generator
• Before placing the generator system into service, the fuel system
lines must be properly purged and leak tested.
• NO leakage is permitted.
WARNING
Propane and Natural Gas are extremely flammable
and explosive.
Fire or explosion can cause severe burns or
death.
• The entire flexible gaseous pipe must be visible for periodic
inspection and must not be concealed within, contact, or run
through any wall, floor, or partition.
CAUTION
The supplied flexible gaseous pipe is not to be installed
underground or in contact with the ground.
Page 12
Fuel Consumption
See Figure 7 for estimated fuel supply requirements at half
and full load for both natural gas and LP vapor.
Fuel Pipe Sizing
Figures 8 and 9 provide the maximum capacity of pipe in
cubic feet of gas per hour for gas pressures of 0.5 psi or
less and a pressure drop of 0.3 in. water column. Specific
gravity of gas is shown.
Listed values compensate for a nominal amount of
restriction from bends, fittings, etc. If an unusual number of
fittings, bends, or other restrictions are used, please refer to
federal and local codes.
10
NPT 10ft 15ft 20ft 30ft 40ft 50ft 60ft 70ft 80ft 90ft 100ft
3/4” 277 192 158 126 107 95 87 79 74 69 65
1” 428 360 293 236 202 180 164 151 139 129 123
Liquid Propane (LP) (sg=1.50)
Figure 9 — LIQUID PROPANE (LP) GAS Pipe Size - Gas Flow Chart, in cubic feet per hour
Natural Gas* LP Vapor**
1/2 Load Full Load 1/2 Load Full Load
12kW
102 195 41 79
15kW
140 218 66 96
* = Natural Gas is in cubic feet per hour
** = LP Vapor is in cubic feet per hour
Figure 7 — Fuel Supply Requirements
NPT 10ft 15ft 20ft 30ft 40ft 50ft 60ft 70ft 80ft 90ft 100ft
3/4” 346 293 240 192 163 145 132 120 113 106 99
1” 653 549 446 360 307 274 250 230 211 197 187
Natural Gas (sg=0.65)
Figure 8 — NATURAL GAS (NG) Pipe Size - Gas Flow Chart, in cubic feet per hour
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Fuel Comparison Chart
The fuel comparison chart shown below is provided for your
reference.
Size of Propane Tank Required at Various
Temperatures When Kept at Least Half Full
Given the gas withdrawal rate and the lowest average winter
temperature, an installer can specify the required LP storage
tank size. The table below provides guidance on tank size
selection.
Required Propane Tank Size (Lowest Average Winter Temperature), in Gallons
Fuel Comparison Chart
Withdrawal Rate 32°F 20°F 10°F 0°F -10°F -30°F -40°F
50 CFH 115 115 115 250 250 400 600
100 CFH 250 250 250 400 500 1000 1500
150 CFH 300 400 500 500 1000 1500 2500
200 CFH 400 500 750 1000 1200 2000 2500
300 CFH 750 1000 1500 2000 2500 4000 5000
Physical Properties Propane Natural Gas
Normal Atmospheric State Gas Gas
Boiling Point (in °F):
Initial -44 -259
End -44 -259
Heating Value:
BTU per gallon (Net LHV*) 83,340 63,310
BTU per Gallon (Gross**) 91,547
Cubic Feet (Gas) 2,500 1,000
Density*** 36.39 57.75
Weight† 4.24 2.65
Octane Number:
Research 110+ 110+
Motor 97
*LHV (Low Heat Value) is the more realistic rating.
**Gross Heat Value does not consider heat lost in the form of water during
combustion.
***Density is given in "Cubic Feet of Gas per Gallon of Liquid".
†Weight is given in "Pounds per Gallon of Liquid".
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System Connections
Compare this illustration with your generator to familiarize yourself with the location of these important connections:
Wiring for the 10 Pole Connector:
• Fault Contacts — Use NO, COM and NC to hook up a
siren, light, etc. to alert for a fault. Contacts reverse
state upon a fault condition.
• Remote LED Output — Use this to hook up the remote
LED supplied with the generator. The remote LED will
turn on and off in a series of blinks (Fault Codes) if
certain faults are detected in the generator.
• Transfer Switch Communication — Use TxRx and
TxRx GND to transfer switch and optional wireless
StatStation™ to monitor generator functions.
• +12 Volt DC, .5 Amp Output — Internal power supply.
Wiring for the 2 Pole Connector:
• 240 Volt Utility — Use to hook up the 240V utility
leads from the transfer switch to the generator.
+12 Volt DC,
.5 Amp Output
240 Volt Utility
Remote LED Output
Transfer Switch
Communication
Fault Contacts
10 Pole Connector
2 Pole Connector
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System AC Connections
A single-phase, three-wire AC connection system is used in
the generator system. The stator assembly consists of a pair
of stationary windings with two leads brought out of each
winding. The junction of leads 22 and 33 forms the neutral
lead, as shown schematically and as wiring diagram in
Figure 10. A complete schematic and wiring diagram can be
found in the illustrated parts list manual.
NOTE: Neutral is not bonded to ground at generator.
Grounding the Generator
Ground the generator system per applicable codes,
standards, and regulations. The generator GND lug is located
inside the control panel door under the circuit breaker cover.
Utility Circuit Connection
"240V Utility" leads must be routed in conduit. Functions are
briefly described as follows:
• "240V Utility" delivers power to the generator’s circuit
board, optional battery and oil warmer, charge the
battery and when utility is lost the generator will start.
Using provided 2 pole connector and installer-supplied
minimum 300V, 14 AWG copper wire, connect each control
circuit terminal in the generator to the Automatic Transfer
Switch.
Fault Detection System
The generator's control panel has a digital display to show
fault codes. It will display a fault code if certain faults are
detected in the system. An extra LED and mounting plate is
supplied so that it can be installed at a convenient indoor
location. It will turn on and off in a series of blinks if certain
faults are detected in the system. The owner will use it to
observe the status of the generator system. Consult with the
owner for a convenient location.
To install the remote LED panel:
• Push the LED through the mounting plate from the
front until it snaps in place.
• Using provided 10 pole connector and installer-supplied
minimum 18 AWG wire, connect the remote LED to the
generator control board. Use wire nuts to attach wire to
LED leads.
IMPORTANT: The LED is polarity sensitive.
• Attach mounting plate to installer-supplied electrical
box.
Refer to Fault Detection System in the Operator’s Manual for
operation.
Figure 10 — System AC Connections
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System Control Panel
Figure 11 depicts the generator system control panel, located
inside the generator housing. Below are brief descriptions of
the controls used during installation. More information may
be found in the Operator’s Manual.
System Switch
This two-position switch is the most important control on
the system and is used as follows:
•“AUTO” position is the normal operating position. If a
utility power outage is sensed, the system will start the
generator. When utility power is restored, lets the
engine stabilize internal temperatures, shuts off the
generator, and waits for the next utility power outage.
•“OFF” position turns off running generator, prevents
unit from starting and resets any detected faults.
15 Amp Fuse
Protects the generator system DC control circuits. If the fuse
has ‘blown’ (melted open) or was removed, the engine
cannot crank or start. Replace the fuse using only an
identical ATO 15A fuse. One spare fuse is supplied with the
unit.
Before Initial Start-up
Engine Oil
This engine is shipped from the factory filled with the
recommended oil. Before starting the engine, check oil level
and ensure that engine is serviced as described in the engine
operator’s manual.
Oil Considerations
Your generator system is equipped with an engine that has
been pre-run at the factory.
The system is filled with synthetic oil (API SJ/CF 5W-30W).
This allows for system operation in the widest range of
temperature and climate conditions.
NOTE: The use of synthetic oil does not alter the required oil
change intervals described in the engine operator’s manual.
Battery Connection
The generator system is supplied with a 12 Volt DC, AGM
type, 55 Amp-Hour, valve regulated battery. It is a sealed,
lead-acid rechargeable battery. It is installed in the unit and
the battery cables are connected at the factory. The unit’s
15 Amp fuse, which isolates the battery and prevents the unit
from starting, has been removed for shipping. The battery will
lose some charge charge prior to installation of the generator.
If battery voltage is below 12 Volts, charge the battery.
IMPORTANT: If battery voltage is below 5 Volts, it may not
take a charge and you will need a new battery.
Charging the Battery
If it is necessary to charge the battery, proceed as follows:
1. Set generator's system switch to OFF.
2. Remove 15 Amp fuse from control panel.
3. Disconnect negative battery cable to negative battery
terminal (indicated by NEGATIVE, NEG, or (-).
4. Charge battery with battery charger at 2 Amps until
battery holds 12 Volts.
NOTE: DO NOT exceed 13.7 Volts charging.
• DO NOT attempt to jump start the battery.
• Damage to equipment resulting from failure to follow this
instruction will void warranty.
NOTICE
Failure to disconnect negative battery cable will result in
equipment failure.
• Refer to engine manual for oil fill information.
• Damage to equipment resulting from failure to follow this
instruction will void warranty.
NOTICE
Any attempt to crank or start the engine before it has been
properly serviced with the recommended oil will result in
equipment failure.
Manual Over-Ride
Switch
Set Exercise
Switch
System Switch
Digital Display
15 Amp Fuse
Service Tool
Circuit
Breaker
Figure 11 — Generator System Control Panel
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NOTE: With the battery installed and utility power available to
the Automatic Transfer Switch, the battery receives a trickle
charge whenever the engine is not running. This process
may take up to 72 hours to fully charge a battery from 5
Volts. The trickle charge cannot be used to recharge a
battery that is completely discharged.
5. Connect negative battery cable to negative battery
terminal (indicated by NEGATIVE, NEG, or (-)).
6. Ensure hardware on both positive and negative battery
terminals is secure.
7. Reinstall 15 Amp fuse in control panel.
8. Set generator's system switch to AUTO.
Servicing the Battery
If it is necessary to service the battery, proceed as follows:
1. Open “Control Panel” access door.
2. Set generator's system switch to OFF.
3. Remove 15 Amp fuse from control panel.
4. Service or replace battery as required.
5. Connect red battery cable to battery positive terminal
(indicated by POSITIVE, POS, or (+)).
6. Connect negative battery cable to negative battery
terminal (indicated by NEGATIVE, NEG, or (-).
7. Ensure hardware on both positive and negative battery
terminals is secure.
8. Reinstall 15 Amp fuse in control panel.
9. Set generator's system switch to AUTO.
10. Close “Control Panel” access door.
Fuel Supply System
Ensure that all fuel pipe connections are tight, secure and
without leaks.
Ensure that all gas line shutoff valves are OPEN and that
adequate fuel pressure is available whenever automatic
operation is desired.
Fuel System Selection
The engine of your residential generator system is factory
calibrated to run on natural gas (NG). It may also be
operated on liquefied petroleum (LP) vapor. There is no
additional hardware/equipment required to switch between
either fuel. However, LP fuel inlet pressure must be between
11 and 14 inches water column.
To configure the fuel system for LP use:
1. Open control panel and oil fill access doors.
2. Set generator's system switch to OFF.
3. Remove 15 Amp fuse from control panel.
Proceed below using the configuration instructions
appropriate to the generator system.
For a 12kW generator:
4. Connect the fuel select solenoid by joining the two-pin
electrical connector shown in Figure 12.
5. Reinstall 15 Amp fuse in control panel.
6. Set generator's system switch to AUTO.
7. Close control panel and oil fill access doors.
The system is now ready to operate automatically using LP
fuel. With a fixed main jet for LP gas, there is no need to
perform any engine adjustments for LP operation.
• DO NOT install this fuse until all plumbing and wiring has been
completed and inspected.
CAUTION
Installing the 15A fuse could cause the engine to
start.
• DO NOT dispose of battery in a fire.
• Do not allow any open flame, spark, heat, or lit cigarette during
and for several minutes after charging a battery.
• DO NOT open or mutilate the battery.
• Wear protective goggles, rubber apron, and rubber gloves.
• Remove watches, rings, or other metal objects.
• Use tools with insulated handles.
WARNING
Storage batteries give off explosive hydrogen gas
during recharging.
Slightest spark will ignite hydrogen and cause
explosion.
Battery electrolyte fluid contains acid and is
extremely caustic.
Contact with battery contents will cause severe
chemical burns.
A battery presents a risk of electrical shock and
high short circuit current.
Figure 12 — Fuel Select Solenoid Connection
Push two connectors
together
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16
For a 15kW Generator:
4. Remove cap from LP inlet on T-valve (Figure 13).
5. Remove fuel line from NG inlet.
6. Place cap from LP inlet onto NG inlet.
7. From oil fill access area, pull fuel line out of top hole.
8. Remove and reverse fuel hose bushing and plug in
sheet metal bulkhead. (Plug in top hole, bushing in
bottom hole.)
9. Insert fuel hose in bottom hole towards fuel regulator.
IMPORTANT: Failure to route fuel line through bottom hole
may cause the fuel line to kink. When tightening fuel hose
fittings make certain the fuel hose does not twist or kink. If
the fuel line kinks, the generator may start but will not
operate properly.
10. Connect fuel line to LP inlet.
11. Reinstall 15 Amp fuse in control panel.
12. Set generator's system switch to AUTO.
13. Close control panel and oil fill access doors.
The system is now ready to operate automatically using
LP fuel.
Initial Start-Up (No Load)
Begin testing the system without any electrical loads
connected, as follows:
1. Set generator’s main circuit breaker to its ON (closed)
position.
2. Install 15 Amp fuse in control panel.
3. Set generator’s system switch to AUTO.
4. Push MANUAL OVER-RIDE switch on generator control
panel.
NOTE: When the generator system is started for the very
first time, it will require that air in the gaseous fuel lines be
purged. This may take a few minutes.
5. DO NOT crank engine for more than 10 seconds, then
pause for 10 seconds to reduce heat in the starter.
6. Repeat process until engine starts.
7. Listen for unusual noises, vibration or other indications
of abnormal operation. Check for oil leaks while engine
runs.
8. Let engine warm up for about five minutes to allow
internal temperatures to stabilize.
9. Connect an accurate AC voltmeter and a frequency
meter to check generator output at load side of circuit
breaker. Voltage should be 239-262 Volts, frequency
should be 62.0 - 62.5 Hz.
NOTE: If either parameter is outside these ranges, perform
the Engine Adjustments described below.
10. Check generator output between one of the generator
connection lugs and the neutral lug, then between the
other generator connection lug and the neutral lug. In
both cases, voltage reading should be between
121-131 Volts.
11. Push and hold MANUAL OVER-RIDE switch on
generator control panel again until engine stops.
IMPORTANT: DO NOT proceed until you are certain that
generator AC voltage and frequency are correct and within
the stated limits. To obtain the proper generator frequency,
see Engine Adjustments.
Figure 13 — T - Valve
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17
Engine Adjustment
There are regional variances in the composition of natural
gas. Each generator system is adjusted at the factory for NG
operation. If the generator output voltage or frequency
measured during Initial Start-Up (paragraph #9, earlier) is
outside the listed ranges, the combustibility of the gas
supplied at the installation site may be substantially different.
To adjust the engine for this difference, proceed as follows.
1. Open the oil drain and control panel access doors.
2. Remove the four screws that hold the circuit breaker
cover to the air intake guard (Figure 14).
3. Connect an accurate frequency meter to the line side of
the generator’s main circuit breaker.
4. Ensure that the 15 Amp fuse is installed.
5. Set the generator’s main circuit breaker ON.
6. Set the generator’s system switch to AUTO.
7. Push MANUAL OVER-RIDE switch on control panel.
When the engine starts, allow it to warm up for five
minutes.
8A. For a 12kW generator, normal no load frequency is
62.0 to 62.5 Hz. If adjustment is needed at no load,
slowly rotate the governor adjustment nut (Figure 15)
clockwise and/or counterclockwise until frequency is
62.0 to 62.5 Hz.
8B. For a 15kW generator, normal no load frequency is
62.0 to 62.5 Hz. If adjustment is needed at no load,
slowly rotate the governor adjustment screw
(Figure 16) clockwise and/or counterclockwise until
frequency is 62.0 to 62.5 Hz.
9. Push and hold MANUAL OVER-RIDE switch on control
panel again until engine stops.
10. Turn the service disconnect to the transfer switch off.
After a short time delay, the transfer switch will connect
to the generator.
11. Load generator to full load.
12. Connect an accurate frequency meter to the load side of
the generator’s main circuit breaker. Frequency should
be above 57.0 Hz.
13. If frequency is below 57.0 Hz, slowly rotate the
governor adjustment nut or screw clockwise and/or
counterclockwise until frequency is above 57.0 Hz.
14. Turn the service disconnect to the transfer switch on.
The transfer switch will connect to the utility after five
minutes.
15. After the engine has stopped running,
• If an adjustment was made in step 13, repeat steps
3 through 9.
• If an adjustment was not made in step 13, proceed to
step 16.
IMPORTANT: If the no load frequency falls out of the no load
parameter after full load adjustment is made, contact an
authorized service center.
16. Reinstall the circuit breaker cover to the air intake
guard.
17. Close the oil drain and control panel access doors.
This completes the generator installation process. Proceed
with transfer switch and other system component
installation. Be sure to perform the Installation Inspection.
Figure 14 — Accessing Back of Circuit Breaker
Figure 15 — Governor Adjustment Nut
Governor
Adjustment
Nut
Figure 16 — Governor Adjustment Screw
Governor
Adjustment
Screw
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Controls
All generator system controls are fully described in the
Operator’s Manual. Please refer there for full information.
Operation
The primary source of generator system operating
instructions is the Operator’s Manual. Please refer to the
Operator’s Manual for detailed information. The following is a
brief overview.
The generator’s control panel houses a logic control circuit
board. This control board constantly monitors utility power
source voltage. Should that voltage drop below a preset
level, control board action will signal the engine to crank and
start.
When utility source voltage is restored above a preset
voltage level, the engine is signaled to shut down.
The actual system operation is not adjustable and is
sequenced by sensors and timers on the control board, as
follows:
Utility Voltage Dropout Sensor
• This sensor monitors utility source voltage.
• If utility source voltage drops below about 70 percent
of the nominal supply voltage, the sensor energizes a
10 second timer. The timer is used to ‘sense’ brownouts.
• Once the timer has expired, the engine will crank and
start.
Utility Voltage Pickup Sensor
This sensor monitors utility power supply voltage. When that
voltage is restored above 80 percent of the nominal source
voltage, a time delay starts timing and the engine will go to
engine cool-down.
Engine Cool-down Timer
• When the load is transferred back to the utility power
source, the engine cool-down timer starts timing.
• The timer will run for about one minute, then the
generator will stop.
• Minimum engine run time is 5 minutes.
Setting Exercise Timer
The generator system is equipped with an exercise timer that
will start and exercise the system once every seven days.
During this exercise period, the unit runs for approximately
20 minutes and then shuts down. Electrical load transfer
DOES NOT occur during the exercise cycle (unless an utility
power outage occurs).
A switch on the control panel is labeled “Set Exercise” (see
Figure 11). The specific day and the specific time of day this
switch is pressed is programmed into the control board
memory. This date and time is then used to automatically
initiate the system exercise cycle. The LED on the control
panel will flash until the set exercise is set.
To perform the Set Exercise procedure:
1. Choose the day and time you want your generator
system to exercise.
2. On that day and time, press and hold down the “Set
Exercise” switch for three seconds.
NOTE: The LED will flash until the switch is pressed for three
seconds, then the LED will illuminate for 5 seconds and turn
off.
For example, if you press the “Set Exercise” switch on
Sunday morning at 10:00 AM, the unit will run an exercise
cycle the following Sunday at 10:00 AM (+/- 1/2 hour).
NOTE: “Set Exercise” will only work if the unit is in the
Automatic mode and this exact procedure is followed. The
exerciser will need to be re-set if the 15 Amp fuse is
removed or changed, or if the 12 Volt DC battery is
disconnected.
If you want to change the day and time the unit exercises,
simply perform the “Set Exercise” procedure at the exact
weekday and time you want it to take place.
Installation Inspection
Before placing the generator system into service, inspect the
entire installation carefully.
Complete the ”Installation Checklist” as you make the
inspection. Ensure all items have been filled-in and all
signatures have been obtained. Return the completed form
to your records department.
Page 21
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Notes
Page 22
20
Schematic and Wiring Diagram for Models GEN12S and GEN20B
Page 23
21
Schematic and Wiring Diagram for Models GEN15S and GEN25B
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