A.O. Smith 12 40GPC T 100 How to use

1
Printed in U.S.A. 10/10 318181-000
SERVICE HANDBOOK FOR
STANDARD RESIDENTIAL
HIGH EFFICIENCY ATMOSPHERIC VENT
(FVIR) GAS WATER HEATERS
MODELS:
GAHH 40 100,
GP 6 40YPC T 100,
PCG6240T403NOV 100,
PCG2J4040T3NOV 100,
12 40GPC T 100,
PCG2J4040T3NOV 100,
GAHH 50 100,
GP 6 50YPC T 100,
PCG250T403NOV 100,
PCG2J5040T3NOV 100,
12 50GPC T 100,
PCG2J5040T3NOV 100

2
ALL TECHNICAL AND WARRANTY QUESTIONS
SHOULD BE DIRECTED TO THE LOCAL DEALER FROM WHOM THE WATER HEATER WAS PURCHASED.
IF YOU ARE UNSUCCESSFUL, CONTACT A. O. SMITH WATER HEATERS RESIDENTIAL TECHNICAL ASSISTANCE
AT 1-800-527-1953 OR WWW.HOTWATER.COM.

3
Your safety and the safety of others is extremely important in the servicing of this water heater. Many
safety-related messages and instructions have been provided in this handbook and on the water heater
to warn you and others of a potential hazard. Read and obey all safety messages and instructions
throughout this handbook. It is very important that the meaning of each safety message is understood
by you and others who service this water heater.
The information contained in this handbook is designed to answer commonly faced situations encoun-
tered in the operation of the standard Residential Gas product line and is not meant to be all-inclusive.
If you are experiencing a problem not covered in this handbook, please contact the Technical Informa-
tion Center listed on the back of this handbook for further assistance. Additional information is also
available on the web site listed on the back of this handbook. This handbook is intended for use by
licensed plumbing professionals and reference should be made to the Installation Instructions and Use
& Care Guide accompanying the product. This handbook contains supplemental information to the
Installation Instructions and Use & Care Guide.
When servicing residential water heaters, it is essential that you return the unit to a safe condition
before you leave the site. All original components must be re-installed and all safety measures must be
implemented. In addition, the recommended water temperature setting is 120° F.
IMPORTANT: It is recommend that on every service call an inspection & cleaning of the air
intake chamber screen and combustion chamber and air diverter assembly be performed. See
page 24.
Tools Required (for servicing gas models):
• phillips head screw driver
• 3/8, 7/16, & 3/4 inch open end wrenches
• 3/16 inch Allen wrench
• 1-1/16 inch – 6 point – socket – for anode removal
• 5/16” nut driver
• pliers
• electrical multimeter (with alligator leads)
• digital or analog manometer
• gas pressure gauge
• Teflon®tape
• hose – to drain tank
Teflon®is a registered trademark of E.I. Du Pont De Numours and Company.
SERVICE HANDBOOK
Digital manometer shown.

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Fire or Explosion Harzard
Do not store or use gasoline or other flammable vapors and
liquids in the vicinity of this or any other appliance.
Avoid all ignition sources if you smell Natural or LP gas.
Do not expose water heater control to excessive gas
pressure.
Use only gas shown on rating plate.
Maintain required clearances to combustibles.
Keep ignition sources away from faucets after extended
period of non-use.
Read instruction manual before
installing, using or servicing
water heater.
Do not operate water heater if flood damaged.
Install in location with drainage.
Fill tank with water before operation.
Be alert for thermal expansion.
Refer to instruction manual for installation and service.
Improper installation and use may result
in property damage.
Breathing Hazard - Carbon Monoxide Gas
Install vent system in accordance with
codes.
Do not operate water heater if flood
damaged
Heater should not be installed for High
Altitude operation above 10,100 feet
(3,078 m).
Do not operate if soot buildup.
Do not obstruct water heater air intake
with insulating jacket.
Do not place chemical vapor emitting
products near water heater.
Gas and carbon monoxide detectors
are available.
Breathing carbon monoxide can cause brain damage or death.
Always read and understand instruction manual.

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TABLE OF CONTENTS
INTRODUCTION:
Service Handbook Introduction...........................................................................................................................3
Warnings and Cautions.......................................................................................................................................4
Table Of Contents ...............................................................................................................................................5
INSTALLATION / OPERATION:
Basic Installation & Operation.............................................................................................................................6
Combustion Air and Vent System Requirements .......................................................................................... 7-10
KNOW YOUR WATER HEATER:
Know the Water Heater’s Component Parts ................................................................................................11-13
Water Heater Operation ....................................................................................................................................14
Filling and Draining the Water Heater ...............................................................................................................15
Lighting Instructions ..........................................................................................................................................16
ADJUSTING TEMPERATURE CONTROL:
Adjusting the Temperature on the Electronic Control Display...........................................................................17
Using the Electronic Control Display........................................................................................................... 18-19
Electronic Control Display Troubleshooting ................................................................................................ 20-23
COMPONENTS REMOVAL / REPLACING:
External Inspection and Cleaning .....................................................................................................................24
Electronic Control Display Removal / Replacement .........................................................................................25
Powered Anode Removal / Replacement ................................................................................................... 26-27
Pressure Switch Removal / Replacement.........................................................................................................28
Transformer Removal / Replacement ......................................................................................................... 29-30
Air Intake Chamber Box Removal / Replacement ...................................................................................... 31-33
Wiring Harnesss Removal / Replacement .................................................................................................. 34-36
Air Intake Chamber Fan Removal / Replacement ...................................................................................... 37-38
Pressure Tubing Removal / Replacement .................................................................................................. 39-40
Inner Door/Manifold/Burner Assembly Removal / Replacement................................................................. 41-42
Flame Sense/Hot Surface Igniter Removal / Replacement ..............................................................................43
Burner Removal / Replacement.................................................................................................................. 44-46
Burner Orifice Removal / Replacement ...................................................................................................... 47-49
Gas Control Valve/Thermostat Removal / Replacement............................................................................. 50-52
CHECKPOINTS / GENERAL INFORMATION:
Checking the Gas Supply Pressure ..................................................................................................................52
Gas Water Heater Sizing Guide -and- Leakage Checkpoints.........................................................................53
General Information .................................................................................................................................... 54-55

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Exhaust Vent to
Ouside of Building
Union
Union
Water
Shut-Off
Valve
Water
Supply- Cold*
Expansion Tank
Pressurize to Equal
Supply Water Pressure*
(Relieve water pressure
on the expansion tank
before adjusting air
pressure.)
Temperature-Pressure Relief Valve
with discharge piped to an
adequate drain. Do not cap or plug.
6” Maximum Air Gap
NOTE: Local codes
may vary.
Drain
Gas Control Valve/Thermostat
Recommended setting of 120°F.**
Metal Drain Pan piped to an adequate drain.
NOTE: Drain pan diameter must be at least
2 inches wider than the diameter of the
water heater.
Sediment Trap
(Drip Leg) 3” Minimum.
Gas
Supply
To Fixtures - Hot
Air is drawn in for combustion.
Keep area clean and free from
flammables and flammable vapors.
The water heater must be installed according to all local and state codes or in the absence of local
and state codes, the “National Fuel Gas Code”’ ANSI Z223.1(NFPA 54)- current edition.
INSTALLATION OF RESIDENTIAL GAS WATER HEATER
See Labels and
Installation Instructions
and Use & Care Guide
for clearances.
* NOTE: If on a well system the expansion tank should be set to the maximum pressure of the pump tank.
** White-Rodgers® gas control valve/thermostat shown in this figure.
*Massachusett: Install
a vacuum relief in cold
water line per section
19 MGL 142.
Do not cap or plug.
Union
Manual Gas Shut-off Valve
Untempered
Hot Water
Tempered Water
To Fixtures
Cold
Water
Inlet
Hot
Water
Outlet
Mixing Valve
(Set to 120°F)
Follow the Mixing Valve
Manufacturer’s Instructions
Control
Display
FV Sensor
Bracket
Air Intake Chamber
Electrical Plug
Use Draft Hood
supplied with unit
BASIC INSTALLATION & OPERATION
Figure 1

7
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS
Table 1:
BTUH Input
Minimum Square
Feet with
8’ Ceiling
Typical Room
with 8’ Ceiling
30,000 188 9 x 21
45,000 281 14 x 20
60,000 375 15 x 25
75,000 469 15 x 31
90,000 563 20 x 28
105,000 657 20 x 33
120,000 750 25 x 30
135,000 844 28 x 30
IMPORTANT:
• The area must be open and be able to provide
the proper air requirements to the water
heater. Areas that are being used for storage
or contain large objects may not be suitable
for water heater installation.
• Water heaters installed in open spaces in
buildings with unusually tight construction may
still require outdoor air to function properly. In
this situation, outside air openings should be
sized the same as for a confined space.
• Modern home construction usually requires
supplying outside air into the water heater
area.
• Room exhaust fans may effect air
requirements.
Confined Space: For the correct and proper
operation of this water heater, ample air must be
supplied for the combustion, ventilation, and dilu-
tion of flue gases. Small enclosures and confined
areas must have two permanent openings so that
sufficient fresh air can be drawn from outside of
the enclosure. One opening shall be within 12
inches of the top and one within 12 inches of the
bottom of the enclosure.
The size of each opening (free area) is deter-
mined by the total BTUH input of all gas utilization
equipment (i.e., water heaters, furnaces, clothes
dryers, etc.) and the method by which the air is
provided. The BTUH input can be found on the
water heater rating plate. Additional air can be
provided by two methods:
1. All air from inside the building.
2. All air from outdoors.
CLOSET
OR
OTHER
CONFINED
SPACE
12” MAXIMUM
PERMANENT
OPENINGS TO
THE OUTSIDE OR
ADDITIONAL
ROOMS WITHIN
THE BUILDING
12” MAXIMUM
Combustion Air Requirements:
WARNING
Carbon Monoxide Warning
Water heater must be vented to outdoors.
Vent must be installed by a qualified technician using
the local and state codes or, in the absence of local
and state codes, the National Fuel Gas Code,
ANSI Z223.1 (NFPA 54) - current edition, and/or the
installation instructions.
Examples of a qualified technican include: gas
technicians, authorized gas company personel, and
authorized service persons.
Failure to so do can result in death or carbon monoxide
poisoning.
IMPORTANT: Air for combustion and ventilation
must not come from a flammable or corrosive at-
mosphere. Any failure due to flammable or corro-
sive elements in the atmosphere is excluded from
warranty coverage.
The following types of installation (not limited to
the following) will require outdoor air for combus-
tion due to chemical exposure and may reduce
but not eliminate the presence of corrosive chemi-
cals in the air:
• beauty shops
• photo processing labs
• buildings with indoor pools
• water heaters installed in laundry, hobby, or
craft rooms
• water heaters installed near chemical storage
areas
• water softeners
Combustion air must be free of acid-forming
chemicals such as sulfur, fluorine, and chlorine.
These elements are found in aerosol sprays, de-
tergents, bleaches, cleaning solvents, air freshen-
ers, paint, and varnish removers, refrigerants, and
many other commercial and household products.
When burned, vapors from these products form
highly corrosive acid compounds. These prod-
ucts should not be stored or used near the water
heater, air inlet, or air intake path.
Combustion and ventilation air requirements are
determined by the location of the water heater.
The water heater may be located in either an
open (unconfined) area or in a confined area or
small enclosure such as a closet or small room.
Confined spaces are areas with less than 50 cubic
feet for each 1,000 BTUH of the total input for all
gas-using appliances.
Unconfined Space: A water heater in an uncon-
fined space uses indoor air for combustion and
requires at least 50 cubic feet for each 1,000
BTUH of the total input for all gas appliances. The
table below shows a few examples of the mini-
mum square footage (area) required for various
BTUH inputs.
Figure 2.

8
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS
All Air from Inside the Building: When
additional air is to be provided to the confined
area from additional room(s) within the building,
the total volume of the room(s) must be of
sufficient size to properly provide the necessary
amount of fresh air to the water heater and other
gas utilization equipment in the area. Each of the
two openings shall have a minimum free area
of 1 square inch per 1,000 BTUH of the total
input rating of all gas utilization equipment in
the confined area, but not less than 100 square
inches for each opening.
Figure 3.
All Air from Outdoors: Outdoor fresh air can be
provided to a confined area either directly or by
the use of vertical and horizontal ducts. The fresh
air can be taken from the outdoors or from crawl
or attic spaces that freely communicate with the
outdoors. Attic or crawl spaces cannot be closed
and must be properly ventilated to the outside.
Ductwork must be of the same cross-sectional
area as the free area of the opening to which
they connect. The minimum dimension of
rectangular air ducts cannot be less than three
inches. The size of each of the two openings is
determined by the method in which the air is to
be provided. Refer to the table below to calculate
the minimum free area for each opening.
Louvers and Grilles: In calculating free
area for ventilation and combustion air supply
openings, consideration must be given to the
blocking effect of protection louvers, grilles, and
screens. These devices can reduce airflow, which
in turn may require larger openings to achieve the
required minimum free area. Screens must not be
smaller than 1/4” mesh. If the free area through
a particular design of louver or grille is known, it
should be used in calculating the specified free
area of the opening. If the design and free area
are not known, it can be assumed that most wood
louvers will allow 20 - 25% of free area while
metal louvers and grilles will allow 60 - 75% of
free area. Louvers and grilles must be locked
open or interconnected with the equipment so that
they are opened automatically during equipment
operation. Keep louvers and grilles clean and free
of debris or other obstructions.
Minimum Free Area of Permanent Openings for
Ventilation and Combustion Air Supply - All Air from
Outdoors Only.
Based on total BTUH input rating for all utilizing
equipment within the confined space.
Opening Source
Minimum Free Area
Per Opening (sq. in.)
Reference
Drawing
*Direct to outdoors 1 sq. in, per 4000 BTUH Figure 4
Ver tical Ducts 1 sq. in, per 4000 BTUH Figure 5
Horizontal Ducts 1 sq. in, per 2000 BTUH Figure 6
Single Opening 1 sq. in, per 3000 BTUH Figure 7
Example: A water heater with an input rating of 50,000 BTUH
using horizontal ducts would require each opening to have a
minimum free area of 25 square inches.
Minimum free area = 50,000 BTUH x 1 sq. in. / 2000 BTUH = 25
sq. in.
*These openings connect directly with the outdoors
through a ventilated attic, a ventilated crawl space, or
through an outside wall.
Consult the local codes of your area for specific
ventilation and combustion air requirements
CONFINED
SPACE
PERMANENT
OPENINGS
1 SQUARE
INCH/1000
BTUH
(MINIMUM
100 SQ. IN.
FOR EACH
OPENING)
Figure 4.
Figure 5.
ABLE VENT
TO OUTDOORS
INSTALL ABOVE
INSULATION
CONFINED
SPACE
ALTERNATE
AIR INLET
OUTLET
AIR TO
ATTIC 1 SQ.
INCH PER
4000 BTUH
INLET AIR FROM
THE CRAWL SPACE
OPEN
FOUNDATION
VENT
1 SQ. INCH PER
4000 BTUH
100 SQ. INCH MINIMUM (EACH)
ALL AIR FROM OUTDOORS: INLET AIR FROM VENTILATED
CRAWL SPACE/OUTLET AIR TO VENTILATED ATTIC
GABLE VENT
TO OUTDOORS
INSTALL ABOVE
INSULATION
CONFINED
SPACE
OUTLET AIR TO
ATTIC 1 SQ. INCH
PER 4000 BTUH -
100 SQ. INCH MIN.
(EACH)
INLET AIR DUCT
1 SQ. INCH PER
4000 BTUH - 100
SQ. INCH MIN.
(EACH)
12” MAXIMUM
ALL AIR FROM OUTDOORS THROUGH VENTILATED ATTIC

9
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS
Vent Connectors:
1. Type B, Double wall, U.L. Listed Vent Pipe.
2. Single wall Vent Pipe.
Maintain the manufacturer’s specified minimum
clearance from combustible materials when using
type B double wall vent pipe.
Vent connectors made of type B, double wall
vent pipe material may pass through walls or
partitions constructed of combustible material if
the minimum listed clearance is maintained.
Maintain a one inch minimum clearance from all
combustible materials when using single wall vent
pipe.
IMPORTANT: Single wall vent pipe cannot be
used for water heaters located in attics and may
not pass through attic spaces, crawl spaces or
any confined or inaccessible location. A single wall
metal vent connector cannot pass through any
interior wall.
When installing a vent connector, please note the
following
• Install the vent connector avoiding
unnecessary bends, which create resistance
to the flow of vent gases.
• Install without dips or sags with an upward
slope of at least 1/4-inch per foot.
• Joints must be fastened by sheet metal
screws or other approved means. It must be
supported to maintain clearances and prevent
separation of joints and damage.
• The length of the vent connector cannot
exceed 75% of the vertical vent height.
• The vent connector must be accessible for
cleaning, inspection, and replacement.
• Vent connectors cannot pass through any
ceiling, floor, firewall, or fire partition.
• It is recommended (but not mandatory) that
a minimum 12 inches of vertical vent pipe be
installed on the draft hood prior to any elbow
in the vent system.
IMPORTANT: Existing vent systems must be
inspected for obstructions, corrosion, and proper
installation.
Chimney Connection: IMPORTANT: Before
connecting a gas vent to a chimney, make sure
the chimney passageway is clear and free of
obstructions. The chimney must be cleaned if
previously used for venting solid fuel appliances
or fireplaces. Also consult local and state codes
for proper chimney sizing and application or, in the
absence of local and state codes, the “National Fuel
Gas Code”, ANSI Z223.1(NFPA 54)-current edition.
• The connector must be installed above the
extreme bottom of the chimney to prevent
potentially blocking the flue gases.
Figure 6.
Figure 7.
Vent Pipe System: This water heater must be
properly vented for the removal of exhaust gases
to the outside atmosphere. Correct installation of
the vent pipe system is mandatory for the proper
and efficient operation of this water heater and is
an important factor in the life of the unit.
The vent pipe must be installed according to all
local and state codes or, in the absence of local
and state codes, the “National Fuel Gas Code”,
ANSI Z223.1(NFPA 54)-current edition. The vent
pipe installation must not be obstructed so as
to prevent the removal of exhaust gases to the
outside atmosphere.
U.L. recognized fuel gas and carbon monoxide
(CO) detectors are recommended in all
applications and should be installed using the
manufacturer’s instructions and local codes, rules,
or regulations.
Vent Pipe Size: It is important that you follow the
guidelines in these instructions for sizing a vent
pipe system. If a transition to a larger vent size is
required, the vent transition connection must be
made at the draft hood outlet. DO NOT reduce
the vent size to less than the draft hood outlet
diameter.
1 SQ. INCH PER
2000 BTUH
100 SQ. INCH
MINIMUM (EACH)
CONFINED
SPACE
1 SQ. INCH PER
2000 BTUH 100 SQ. INCH
MINIMUM (EACH)
INLET
OUTLET
OUTDOOR
AIR DUCTS
ALL AIR FROM OUTDOORS USING HORIZONTAL DUCTS
ALTERNATIVE
OPENING
LOCATION
1 SQ. INCH
PER 3000 BTUH
100 SQ. INCH
MINIMUM (EACH)
CONFINED
SPACE
ALL AIR FROM OUTDOORS - USING A SINGLE PERMANENT OPENING

10
• The connector must be firmly attached and
sealed to prevent it from falling out.
• To aid in removing the connector, a thimble or
slip joint may be used.
• The connector must not extend beyond the
inner edge of the chimney as it may restrict
the space between it and the opposite wall of
the chimney
Chimney Termination Vent System
Seal
Do Not Extend
Vent Beyond Edge
Of Chimney
Maintain
Clearance*
Support Strap
3 FT.
Minimum
2 FT. Minimum Above Any Object
Within 10 FT. Horizontally
Slope Up
1/4 Inch
Per Foot
Minimum
Vent
Connector
Figure 8.
Do not reduce the vent to less than the draft
hood outlet diameter. Do not terminate the vent
connector in a chimney that has not been certified
for this purpose. Some local codes may prohibit
the termination of vent connectors in a masonry
chimney.
Vertical Exhaust Gas Vent: Vertical exhaust
gas vents must be installed with U.L. listed type
B vent pipe according to the vent manufacturer’s
instructions and the terms of its listing.
It must be connected to the water heater’s draft
hood by a listed vent connector or by directly
originating at the draft hood opening.
Vertical gas vents must terminate with a listed cap
or other roof assembly and be installed according to
their manufacturer’s instructions.
Gas vents must be supported to prevent damage,
joint separation, and maintain clearances to
combustible materials.
IMPORTANT: This gas vent must be terminated in a
vertical position to facilitate the removal of the burnt
gases.
An unused chimney flue or masonry enclosure
may be used as a passageway for the installation
of a gas vent. NOTE: The chimney flue or masonry
enclosure size may be too large to allow proper
venting.
Common (combined) venting is allowable with
vertical type B vent systems and lined masonry
chimneys as long as proper draft for the water
heater is established under all conditions of
operation. CAUTION: DO NOT common vent this
water heater with any power vented appliance.
The following figures are examples of vent pipe
system installations and may or may not be typical
for your specific application. Consult the “National
Fuel Gas Code”, NFPA 54, ANSI Z223.1-current
edition and the guidelines set forth by prevailing
local codes.
Maintain
Clearance*
Support Strap
3 FT.
Minimum
Vent
Connector
Slope Up
1/4 Inch
Per Foot
Minimum
**Maintain
Specified
Clearance
Venting Gas Vent System With Type B Double Wall Vent Pipe.
2 FT. Minimum Above
Any Object Within
10 FT. Horizontally
Type B Double
Wall Vent Pipe
Figure 9.
Consult the table found in the “National Fuel Gas
Code”, NFPA 54, ANSI Z223.1-current edition to
determine the minimum height from roof to lowest
discharge opening.
Seal
Maintain
Clearance*
Support Strap
Specified Minimum Clearance
Vent
Connector
Slope Up
1/4 Inch
Per Foot
Minimum
Vent Connector
**Maintain
Specified
Clearance
Venting Through Chimney With Type B Double Wall Vent Pipe.
Unused Chimney
Flue Or Masonry
Enclosure
Maintain Manufacturer’s
Listed Vent Cap
Figure 10.
* Maintain vent pipe clearance requirements to local,
state and/or the “National Fuel Gas Code”, ANSI
Z223.1(NFPA 54)-current edition.
** NFPA 211, Standard for Chimneys, Fireplaces,
Vents, and Solid Fuel-Burning Appliances states
that these chimneys are intended to be installed
in accordance with the installation instructions
provided with each chimney support assembly.
Minimum air space clearance to combustible
materials should be maintained as marked on the
chimney sections.
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS

11
KNOW THE WATER HEATER’S COMPONENT PARTS
Figure 11.
Electronic Control Display (Upper Control)
The Electronic Control Display panel used on this water heater provides an easy-to-read, eye level display
for temperature adjustment, fault code diagnostics and recall, powered anode rod operation and setting the
temperature scale for either Fahrenheit (°F) or Celsius (°C).
Gas Control Valve/Thermostat (Lower Control)
The gas control valve/thermostat is where the incoming gas supply is connected to the water heater. It is
used in conjunction with the electronic control display to start or stop main burner operation. There is an
On/Off switch located on the right-hand side of the control. The gas control valve/thermostat is energized
by a 24 VAC power supply transformer and uses a temperature sensing probe to open or close the flow
of gas to the main burner. The gas control valve has an inlet filter built into its body to prevent impurities in
the gas system from contaminating the internal valves and a LED diagnostic light located in the lower right
hand corner of the valve to display any micro-computer fault experienced by the control. On the bottom of
the control is where electrical connections to the other component parts are attached along with the gas
supply (manifold tube) to the main burner. The gas control/valve thermostat of this water heater is suitable
for use on Natural gas only.
Manifold Tube
Control Display,
Anode Rod
Connector
Pressure
Switch / Fan,
FV Sensor
Connector
Power Supply
Transformer
Connector
Igniter/Flame
Sense
Connector
Gas Control Valve/ Thermostat
Temperature Probe
/High Limit Probe
Gas Supply- Inlet
Bottom View
8 Pin Systems
Connector
5 Pin Communications
Connector
3 Pin Ignitor
Connector
2 Pin Power
Connector
1
2
3
4
1
2
3
4
On/Off Switch
located on
the right side.
Figure 12.
Electronic Control Display
(Upper Control)

12
KNOW THE WATER HEATER’S COMPONENT PARTS
Burner/Manifold Door Assembly
The burner/manifold door assembly consists of several components such as: main burner, burner orifice,
manifold tube and flame sense / hot surface igniter. See figure below for the complete list of components
(Figure 13).
*DO NOT operate the water heater without the burner orifices installed.
Burner Screws
Main Burner
Manifold
Tube
Door Gasket
Burner Orifice*
Manifold
Door
View
Port
Flame Sense/
Hot Surface
Igniter Assembly
Flame Sense / Hot Surface
Igniter Assembly
Scoop side to be placed
on the same side as
View Port.
Figure 13.
Air Intake Chamber Fan
The small fan at the top of the air intake chamber
on the side of the water heater is used to draw in
necessary combustion air for the efficient operation
of the main burner. The fan pressurizes the sealed
combustion chamber which in turn allows the flue
baffle inside the center flue tube to slow down the
hot exhaust gases so heat can be extracted into the
water before exiting into the vent system. The air
intake chamber fan runs for about 5 seconds to pre-
purge the combustion chamber before the beginning
of an ignition sequence when there is a call for
heat. The fan will continue to operate while the main
burner is in operation and for about 5 seconds after
the temperature set point has been achieved. The
air intake chamber screen covering the fan should
be inspected and cleaned periodically to assure it is
not limiting air flow into the chamber (Figure 14).
Pressure Switch
A pressure switch in the control string of this water
heater is used to verify there is an adequate flow of
combustion air into the combustion chamber before
and during main burner operation. It is electrically
connected to the gas control valve/thermostat and
controls the opening and closing of the gas valve.
If there is an insufficient air supply being delivered
to the combustion chamber the pressure switch will
not allow the water heater to operate (Figure 15).
Air intake
Chamber
Air intake
Chamber
Screen
Air intake
Chamber
Fan
Figure 14.
Pressure
Switch
Figure 15

13
KNOW THE WATER HEATER’S COMPONENT PARTS
Flammable Vapor Cut Off Switch (FV Sensor)
The water heater is equipped with a FV sensor, for
detecting the presence of flammable vapors (e.g.
spilled gasoline). When the sensor detects those
vapors, the heater will shut down and not operate.
If flammable vapors are detected or the sensor
is inoperative, an icon will flash on the electronic
control display and the heater will go into a lockout
mode. The water heater will not function again until
the flammable vapors have been eliminated and the
control is manually reset using a special Flammable
Vapor sensor reset sequence. (Figure 16).
Power Anode Rod
To protect the glass-lined water tank from corrosion
through electrolysis, this water heater is equipped
with a non sacrificial powered anode rod. Unlike
conventional magnesium or aluminum anode rods
used in water heaters, the powered anode does
not deteriorate and is less likely to contribute to
the occurrence of “Smelly (Rotten Egg) Water”
(Figure 17).
FV Sensor
Figure 16.
Powered
Anode
Rod
Figure 17.
HOW THE WATER HEATER’S COMPONENT PARTS ARE CONNECTED
Pressure
Switch
Control Display
Power Supply
Transformer
Igniter/Flame
Sense Connector
Air Intake
Chamber Fan Anode
Rod
Gas Control
Valve / Thermostat
CAUTION:
LABEL ALL WIRES PRIOR TO
DISCONNECTION WHEN SERVICING
CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERATION.
VERIFY PROPER OPERATION AFTER SERVICING.
FV
Sensor
CAUTION:
DO NOT USE AN EXTENSION
CORD TO CONNECT THE
TRANSFORMER TO AN
ELECTRICAL OUTLET.
Figure 18.

14
WATER HEATER OPERATION
The figure below shows the water heater’s sequence of operation when a call for heat is initiated. The gas
control valve/thermostat will attempt to light the burner three times. If the flame sense rod in the burner/
manifold assembly does not detect ignition, the control will enter lockout mode indicated by the electronic
control display’s flashing of the appropriate status code.
SEQUENCE OF OPERATION
Main burner flame is detected by
flame sense rod. Air intake fan
and main burner will continue to
operate until water temperature
inside the tank reaches
temperature set point.
Gas valve/thermostat will do a
relay check (relay clicks will be
heard).
Display will show temperature
set point during call for heat.
System will verify pressure
switch operation and start a
5 second pre-purge, then air
intake fan will turn off.
Ignitor will start a 12 second
warm up period. “IGN” will
show on display.
Gas valve/thermostat will open
for 4 second trial for ignition
and fan will turn on.
Gas valve/thermostat is de-
energized and air intake fan
continues for a post purge time
of approximately 5 seconds.
Water heater returns to standby
mode.
Call for heat indicated by
flashing of display screen
status codes.
Draft Blower is energized.

15
FILLING, DRAINING AND FLUSHING THE WATER HEATER TANK
It is recommended that the tank be drained and flushed every 6 months to remove sediment which
may build up during operation. The water heater should be drained if being shut down during freezing
temperatures. To drain the tank, perform the following steps:
Adequate Drain
Hose
Outer Door
Figure 19.
1. Turn off the gas to the water heater at the manual gas shut-off valve and turn off the electrical power to
the gas control/thermostat valve.
2. Open a nearby hot water faucet until the water is no longer hot.
3. Close the cold water inlet valve.
4. Remove the outer door and connect a hose to the drain valve and terminate it to an adequate drain or
external to the building (Figure 19).
5. Open the water heater drain valve and allow all the water to drain from the tank. Flush the tank with
water as needed to remove sediment.
6. Close the drain valve, refill the tank, and restart the heater as directed in the lighting instructions on the
front of the heater.
IMPORTANT: Condensation may occur when refilling the tank and should not be confused with a tank leak.
NOTE: If the water heater is going to be shut down for an extended period,
the drain valve should be left open.

16
LIGHTING INSTRUCTIONS
Read and understand these directions thoroughly before attempting to operate the water heater. Make sure
the view port is not missing or damaged. Make sure the tank is completely filled with water before operating
the water heater. The gas control valve/thermostat has an “On/Off Switch” and needs to be turned on
before the water heater is operational. Check the label on the front of the water heater near the gas control
valve/thermostat for the correct gas. Do not start this water heater with any gas other than the one listed on
the label. If you have any questions or doubts, consult the gas supplier or gas utility company. The following
Lighting Instruction label appears on the front of the water heater.
Set the Electronic Display to the lowest setting by first
pressing the COOLER and HOTTER but-
tons together and holding for 1 second. Then press
the COOLER button to the lowest setting.
185741-000
FLAMMABLE
BEFORE OPERATING: ENTIRE SYSTEM MUST BE FILLED WITH WATER AND AIR PURGED FROM ALL LINES.
A.
B.
C.
D.
WHAT TO DO IF YOU SMELL GAS:
Do not try to light any appliance.
Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
If you cannot reach your gas supplier, call the
fire department.
Do not touch any electric switch;
do not use any phone in your building.
1.
1. STOP!
Read the safety information
above on the label.
3.
Set the ON/OFF switch on the gas control to the
"ON" position.
5.
Set the ON/OFF switch on the gas control to the
"OFF" position.
WARNING: If you do not follow these instructions exactly, a fire or
explosion may result causing property damage, personal injury
or loss of life.
Turn on all electrical power to the appliance.
2.
Turn off all electrical power to the appliance if
service is to be performed.
3.
Set the ON/OFF switch on the gas control to the
"OFF" postition.
2.
6. This appliance is equipped with a device
which automatically lights the burner.
DO NOT TRY TO LIGHT THE BURNER BY HAND.
This appliance does not have a pilot. It is equipped with
an ignition device that will automatically light the
burner.
Do not try to light the burner by hand.
BEFORE OPERATING smell all around the appliance
area for gas. Be sure to smell next to the floor because
some gas is heavier than air and will settle on the floor.
Use only your hand to push in the electronic display
buttons and gas control switch. Never use tools.
If the control buttons will not push in, don't try to
repair them, call a qualified service technician. Force
or attempted repair may result in a fire or explosion.
Do not use this appliance if any part has been
under water. Immediately contact a qualified
installer or service agency to replace a flooded
water heater. Do not attempt to repair the unit.
It must
be replaced!
7.
Wait five (5) minutes to clear out any gas.
If you then smell gas,
STOP! Follow "B" in
the safety information above on this label. If you
don't smell gas, go to the next step.
Set the Electronic Display to the lowest
setting by first
pressing the COOLER and
HOTTER but
tons together and holding for 1
second. Then press
the COOLER button to
the lowest setting.
4.
"GAS CONTROL"
FOR YOUR SAFETY READ BEFORE OPERATING
OPERATING INSTRUCTIONS
TO TURN OFF GAS TO APPLIANCE
ON/OFF
SWITCH
ON
OFF
"ELECTRONIC DISPLAY"
DANGER: Hotter water increases the
risk of scald injury. Consult the instruction
manual before changing temperature.
Set the ON/OFF switch on the gas control to the
"ON" postition.
8.
Set the Electronic Display to the desired setting by first
pressing the COOLER and HOTTER but-
tons together and holding for 1 second. Then press
the HOTTER button until the desired setting
is reached.
9.
WARNING: TURN OFF ALL
ELECTRIC POWER BEFORE SERVICING.
10.
If the appliance will not operate, follow the instruc-
tions "TO TURN OFF GAS TO APPLIANCE" and
call your technician or gas supplier.
Figure 20.

17
ADJUSTING THE TEMPERATURE ON THE
ELECTRONIC CONTROL DISPLAY
Adjusting the Temperature Set Point - The thermostat of this water heater has been factory set at its
lowest position. It is adjustable and must be reset to the desired temperature setting to reduce the risk of
scald injury. The electronic control display temperature should be set at approximately 120°F (49°C) and
this is the preferred starting point, see Figure 21 Some states have a requirement for a lower setting. If you
need hotter water, follow directions for temperature adjustment, but beware of the warnings in this section.
Pressing the “COOLER” button decreases temperature and pressing the “HOTTER” button increases
the temperature.
To avoid any unintentional changes in water temperature settings, the control has a tamper resistant
feature for changing the temperature setting. To change the temperature setting follow these instructions:
1. “Unlock” the temperature indicators by holding down both “COOLER” and “HOTTER” temperature
adjustment buttons at the same time for one second (See Figure 21). The temperature indicators will light
up and will only remain on for 30 seconds if no further buttons are pressed. After 30 seconds the control
will go back to “Lock” mode (“Lock” mode indicates a temperature setting is locked into the control
memory).
2. Release both of the temperature adjustment buttons.
A. To decrease the temperature press and release the “COOLER”
button until the desired setting is reache d.
B. To increase the temperature press and release the “HOTTER”
button until the desired setting is reached.
NOTE: Should overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to
the heater.
Water
Temperature
°F
Time for 1st
Degree Burn
(Less Severe Burns)
Time for Permanent Burns
2nd & 3rd Degree
(Most Severe Burns)
110 (normal shower temp.)
116 (pain threshold)
116 35 minutes 45 minutes
122 1 minute 5 minutes
131 5 seconds 25 seconds
140 2 seconds 5 seconds
149 1 second 2 seconds
154 instantaneous 1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15,1978)
Figure 21.
Table 2
Gas Control Valve/Thermostat Settings
COOLER
HOTTER
Electronic Control Display

18
USING THE ELECTRONIC CONTROL DISPLAY
How to select or change the temperature scale from Fahrenheit (°F) to Celsius (°C).
Figure 22.
1. The temperature scale defaults to Fahrenheit (°F).
2. To change to Celsius (°C), press the two temperature adjustment buttons at the same time for more
than five (5) seconds but less than 10 seconds to enter the Temperature Scale Selection mode. In this
mode the currently active temperature scale indicator (°F or °C) will start to flash. When in this mode a
button press of either the red up arrow, or the blue down arrow button will cause the control to toggle
the temperature scale between °F and °C (Figure 22).
3. Once the selection has been made the user may exit this mode by again pressing the two temperature
adjustment buttons at the same time for more than two (2) seconds but less than five (5) seconds. The
control will also time out five (5) seconds after the last button press and return to the normal operational
mode.
Fault Code Diagnostics:
• The control system of this water heater monitors inputs and outputs.
• When the system determines a fault condition is present it will show the
fault on the display.
• Depending on the fault, the system may continue to operate or enter a
timed lockout.
• Lockout time varies depending on the fault.
• When the lockout time expires, if the fault has been corrected, the system
will attempt normal operation.
Fault Code Retrieval:
• The system will display the last eight (8) fault codes.
• The system will display how many days ago each fault occurred, up to 14 days.
Note: A “14” indicates that the fault occurred 14 or more days ago. Interrupting
the power restarts the date code at “00”.
• User must enter Field Service Mode to view information.
• Current water temperature, measured at gas valve/thermostat will also be
displayed in Field Service mode.
Entering Field Service Mode:
1. Press and hold both temperature adjust buttons (Figure 22).
2. Hold both buttons as control passes from the set point display to Temperature Scale Selection menu.
Continue to hold buttons until “CHECK” icon is displayed, then release buttons. This will take 10 to 15
seconds.
3. The display will show the current water temperature, “POWER” icon, “CHECK” icon and will flash any
current fault icons. The backlight will always be displayed while in the Field Service Mode.
Gas Control Valve/Thermostat Settings
COOLER
HOTTER
Electronic Control Display

19
USING THE ELECTRONIC CONTROL DISPLAY
Reviewing Fault Codes:
1. Press the red up arrow button one time.
2. The display will show either E0 or E1.
3. If E0 is shown, there are no faults. By pressing the up arrow button again the display will exit the Field
Service mode, or the control will exit automatically after no button is pressed for five (5) seconds.
4. If E1 is shown, the control will flash the icons of the most recent fault.
5. Pressing the red up arrow button again will shown how many days ago the fault occurred and continue to
flash the corresponding fault icons.
6. Interpreting the day of the fault occurrence is as follows...00 would be today, 01 would be yesterday, up to
14 which would be 14 or more days ago.
7. Continuing to press the up arrow button will scroll through all of the eight (8) most recent faults, if they exist,
and its days ago of occurrence.
8. After the last fault is reached the display will return to the first fault (E1) to allow for the faults to be reviewed
again.
Exiting Field Service Mode:
• There are three (3) methods to exit the Field Service Mode, Manual, Manual and Clear, and Timed Exit.
1. Manual exit is accomplished by pressing both the red up arrow and the blue down arrow buttons for
one (1) second, but less than five (5) seconds while in the Field Service Mode, or by pressing the red
up arrow button one (1) time after the “E0” is displayed during fault review while in the Field Service
Mode. These methods will return the control to the standard operating mode and retain any fault codes
stored in memory.
2. Manual exit and fault clear is accomplished by pressing the red up arrow and the blue down arrow
buttons for five (5) seconds while in the Field Service Mode. This method will return the control to the
standard operating mode and at the end of the five (5) seconds clear all faults stored in memory
and initiate a software reset indicated by all the LCD segments coming on for five (5) seconds. The
temperature setting and scale, etc. will not be altered using this method of exit.
3. Timed exit will occur while in the Field Service Mode if the control detects no button presses for a
period exceeding five (5) minutes. The control will automatically return to the normal operating mode
and keep all fault data retained in memory.
FV-Sense Reset Sequence:
Flammable liquids (such as gasoline, solvents, adhesives, LP gases,
etc.) and other substances emit flammable vapors which can be
ignited by a gas water heater’s hot surface igniter or main burner. The
resulting flashback and fire can cause serious burns to anyone in the
area. This water heater is equipped with a FV sensor for detecting the
presence of flammable vapors. When the sensor detects those vapors,
the unit will shut down and not operate. Even though this water heater
is a flammable vapors ignition resistant water heater and designed to
reduce the chances of flammable vapors being ignited, gasoline and
other flammable substances should never be stored or used in the
same vicinity or area containing a gas water heater or other open flame
or spark producing appliance.
Should the FV-Sensor of this water heater detect the presence of flammable vapors the following FV-Sense
Reset Sequence must be entered into the Electronic Control Display. NOTE: “BEFORE RESETTING THE
FVIR SENSE IN THE ELECTRONIC CONTROL DISPLAY, THOROUGHLY INSPECT THE AREA AND REMOVE
THE SOURCE OF THE FLAMMABLE VAPORS”.
1. Manual reset is accomplished by first turning off the power to the water heater for at least 10 seconds.
2. Then, while pressing the two temperature adjustment buttons on the display, turn the switch on the gas
control valve/thermostat to the on position. All the display icons will start to flash. Temporarily release
both temperature adjust buttons and within 2 seconds, press both temperatures adjust buttons again
until all the display icons are on steady. Release the two temperature adjust buttons. The system will
clear the fault, perform a reset, and normal operation will be restored.
FV Sensor
Figure 23.

20
Please check guidelines below. For your safety, water heater service should be performed only by a qualied service person.
Read the
GENERAL SAFETY INFORMATION supplied by the water heater manufacturer.
1. “POWER” Flashing
Communication Error
The system has detected a
communication error between the
upper and lower controls.
1. Check the 5-conductor data cable that
runs between the upper and lower
controls. Check that the wiring is not
broken, and the connectors on both ends
are properly seated in the mating
connectors.
2. Replace the upper control, if the error code
does not clear - cycle power to the water
heater “O” and “On” to reset.
3. Replace the lower control if the problem persists.
2. “HEATING” and “SHORT” Flashing
The self-diagnostic tests have
found a problem with an internal
circuit.
1. Turn the power o for 10 to 20 seconds
then on again to clear the error code.
2. If the error code persists or cannot be
cleared, replace the lower control.
3. “HEATING” and “OPEN” Flashing
Ignition/ame failure.
The water heater has reached the
maximum number of retries and is
currently locked out for one hour.
Cycle the power to the water
heater o and on to reset.
1. Gas supply is turned o – pressure too
low. Ensure supply and manifold gas
pressures are within requirements in the
installation manual. Manifold gas
pressure is non-adjustable, if pressure is
o by more than 0.3” W.C. (75 Pa)
replace the lower control.
2. Low supply voltage – should be 115 –
125 VAC.
3. Ensure ame sensor is making good
contact with the burner ame, ensure
ame is steady.
4. Ensure the ame sensor is clean – use
pad
to clean the ame sensor.
5. Ensure the hot surface ignitor is
positioned to provide consistent ignition.
6. Check for any cracks in the ignitor
assembly ceramic insulators – replace
ignitor assembly if damaged.
7. Check resistance of the ignitor at room
temperature (77°F – 25°C) at the plug
end. Replace ignitor if the resistance is
not within 1.72 to 2.4 ohms at room
temperature.
4. “HEATING”, “OPEN”, and “SHORT” Flashing
Weak ame sensor current.
1. Ensure ame sensor is making good
contact with the burner ame, ensure
ame is steady.
2. Ensure the ame sensor is clean – use
ultra ne steel wool or Scotch-Brite pad
to clean the ame sensor.
5. “ECO” and “OPEN” Flashing
Water temperature in the tank has
exceeded 185°F (85°C) and has
activated the ECO.
1. Turn the power o for 10 – 20 seconds
then on again to clear this error code.
2. Replace the lower control if the error
code persists.
ultra ne steel wool or Scotch-Brite
TM
TM
CONTROL DISPLAY STATUS PROBLEM SOLUTION
ELECTRONIC CONTROL DISPLAY
ELECTRONIC CONTROL DISPLAY TROUBLESHOOTING