AO Smith Water Heater 12 50GPC T 100 User Manual

SERVICE HANDBOOK FOR  
STANDARD RESIDENTIAL  
HIGH EFFICIENCY ATMOSPHERIC VENT  
(FVIR) GAS WATER HEATERS  
MODELS:  
GAHH 40 100,  
GAHH 50 100,  
GP 6 40YPC T 100,  
GP 6 50YPC T 100,  
PCG250T403NOV 100,  
PCG2J5040T3NOV 100,  
12 50GPC T 100,  
PCG6240T403NOV 100,  
PCG2J4040T3NOV 100,  
12 40GPC T 100,  
PCG2J4040T3NOV 100,  
PCG2J5040T3NOV 100  
Printed in U.S.A. 10/10  
318181-000  
ALL TECHNICAL AND WARRANTY QUESTIONS  
SHOULD BE DIRECTED TO THE LOCAL DEALER FROM WHOM THE WATER HEATER WAS PURCHASED.  
IF YOU ARE UNSUCCESSFUL, CONTACTA. O. SMITH WATER HEATERS RESIDENTIAL TECHNICALASSISTANCE  
AT 1-800-527-1953 OR WWW.HOTWATER.COM.  
2
SERVICE HANDBOOK  
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  
Digital manometer shown.  
Teflon® is a registered trademark of E.I. Du Pont De Numours and Company.  
3
Breathing Hazard - Carbon Monoxide Gas  
Install vent system in accordance with  
codes.  
Do not operate water heater if flood  
damaged  
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.  
Heater should not be installed for High  
Altitude operation above 10,100 feet  
(3,078 m).  
Avoid all ignition sources if you smell Natural or LP gas.  
Do not expose water heater control to excessive gas  
pressure.  
Do not operate if soot buildup.  
Use only gas shown on rating plate.  
Do not obstruct water heater air intake  
with insulating jacket.  
Maintain required clearances to combustibles.  
Keep ignition sources away from faucets after extended  
period of non-use.  
Do not place chemical vapor emitting  
products near water heater.  
Gas and carbon monoxide detectors  
are available.  
Read instruction manual before  
installing, using or servicing  
water heater.  
Breathing carbon monoxide can cause brain damage or death.  
Always read and understand instruction manual.  
Improper installation and use may result  
in property damage.  
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.  
4
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 Orice 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  
5
BASIC INSTALLATION & OPERATION  
INSTALLATION OF RESIDENTIAL GAS WATER HEATER  
Water  
Supply- Cold*  
Water  
Shut-Off  
Valve  
See Labels and  
Exhaust Vent to  
Ouside of Building  
Installation Instructions  
and Use & Care Guide  
for clearances.  
*Massachusett: Install  
a vacuum relief in cold  
water line per section  
19 MGL 142.  
Union  
Use Draft Hood  
supplied with unit  
Union  
Expansion Tank  
Pressurize to Equal  
Supply Water Pressure*  
(Relieve water pressure  
on the expansion tank  
before adjusting air  
pressure.)  
To Fixtures - Hot  
Gas  
Tempered Water  
Supply  
To Fixtures  
Temperature-Pressure Relief Valve  
with discharge piped to an  
adequate drain. Do not cap or plug.  
Untempered  
Hot Water  
Cold  
Water  
Inlet  
Control  
Display  
Manual Gas Shut-off Valve  
Air Intake Chamber  
Hot  
Air is drawn in for combustion.  
Keep area clean and free from  
flammables and flammable vapors.  
Water  
Outlet  
Gas Control Valve/Thermostat  
Recommended setting of 120°F.**  
Mixing Valve  
(Set to 120°F)  
Do not cap or plug.  
Follow the Mixing Valve  
Manufacturer’s Instructions  
6” Maximum Air Gap  
NOTE: Local codes  
may vary.  
Union  
Sediment Trap  
Drain  
(Drip Leg) 3” Minimum.  
Electrical Plug  
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.  
FV Sensor  
Bracket  
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.  
*
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.  
Figure 1  
6
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS  
Combustion Air Requirements:  
Table 1:  
BTUH Input  
Minimum Square  
Feet with  
Typical Room  
with 8’ Ceiling  
WARNING  
Carbon Monoxide Warning  
8’ Ceiling  
30,000  
45,000  
60,000  
75,000  
90,000  
105,000  
120,000  
135,000  
188  
281  
375  
469  
563  
657  
750  
844  
9 x 21  
14 x 20  
15 x 25  
15 x 31  
20 x 28  
20 x 33  
25 x 30  
28 x 30  
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.  
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.  
Failure to so do can result in death or carbon monoxide  
poisoning.  
IMPORTANT: Air for combustion and ventilation  
must not come from a ammable or corrosive at-  
mosphere. Any failure due to ammable or corro-  
sive elements in the atmosphere is excluded from  
warranty coverage.  
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.  
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:  
Room exhaust fans may effect air  
requirements.  
beauty shops  
Conned Space: For the correct and proper  
operation of this water heater, ample air must be  
supplied for the combustion, ventilation, and dilu-  
tion of ue gases. Small enclosures and conned  
areas must have two permanent openings so that  
sufcient 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:  
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, uorine, 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.  
1. All air from inside the building.  
2. All air from outdoors.  
Combustion and ventilation air requirements are  
determined by the location of the water heater.  
The water heater may be located in either an  
open (unconned) area or in a conned area or  
small enclosure such as a closet or small room.  
Conned spaces are areas with less than 50 cubic  
feet for each 1,000 BTUH of the total input for all  
gas-using appliances.  
Unconned Space: A water heater in an uncon-  
ned 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.  
12” MAXIMUM  
CLOSET  
OR  
OTHER  
CONFINED  
SPACE  
PERMANENT  
OPENINGS TO  
THE OUTSIDE OR  
ADDITIONAL  
ROOMS WITHIN  
THE BUILDING  
12” MAXIMUM  
Figure 2.  
7
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS  
All Air from Inside the Building: When  
Minimum Free Area of Permanent Openings for  
Ventilation and Combustion Air Supply - All Air from  
Outdoors Only.  
additional air is to be provided to the conned  
area from additional room(s) within the building,  
the total volume of the room(s) must be of  
sufcient 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 conned area, but not less than 100 square  
inches for each opening.  
Based on total BTUH input rating for all utilizing  
equipment within the conned space.  
Minimum Free Area  
Per Opening (sq. in.)  
Reference  
Drawing  
Opening Source  
*Direct to outdoors 1 sq. in, per 4000 BTUH  
Figure 4  
Figure 5  
Figure 6  
Figure 7  
Vertical Ducts  
Horizontal Ducts  
Single Opening  
1 sq. in, per 4000 BTUH  
1 sq. in, per 2000 BTUH  
1 sq. in, per 3000 BTUH  
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.  
CONFINED  
SPACE  
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.  
*
PERMANENT  
OPENINGS  
Consult the local codes of your area for specific  
ventilation and combustion air requirements  
1 SQUARE  
INCH/1000  
BTUH  
(MINIMUM  
100 SQ. IN.  
FOR EACH  
OPENING)  
ABLE VENT  
TO OUTDOORS  
INSTALL ABOVE  
INSULATION  
Figure 3.  
CONFINED  
OUTLET  
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.  
SPACE  
AIR TO  
ATTIC 1 SQ.  
INCH PER  
4000 BTUH  
INLET AIR FROM  
THE CRAWL SPACE  
ALTERNATE  
AIR INLET  
1 SQ. INCH PER  
4000 BTUH  
100 SQ. INCH MINIMUM (EACH)  
OPEN  
FOUNDATION  
VENT  
ALL AIR FROM OUTDOORS: INLET AIR FROM VENTILATED  
CRAWL SPACE/OUTLET AIR TO VENTILATED ATTIC  
Figure 4.  
GABLE VENT  
TO OUTDOORS  
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.  
INSTALL ABOVE  
INSULATION  
OUTLET AIR TO  
CONFINED  
ATTIC 1 SQ. INCH  
SPACE  
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  
Figure 5.  
8
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS  
Vent Connectors:  
1. Type B, Double wall, U.L. Listed Vent Pipe.  
2. Single wall Vent Pipe.  
1 SQ. INCH PER  
2000 BTUH  
100 SQ. INCH  
MINIMUM (EACH)  
Maintain the manufacturer’s specied minimum  
clearance from combustible materials when using  
type B double wall vent pipe.  
CONFINED  
SPACE  
OUTLET  
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.  
OUTDOOR  
AIR DUCTS  
INLET  
1 SQ. INCH PER  
2000 BTUH 100 SQ. INCH  
MINIMUM (EACH)  
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 conned or inaccessible location. A single wall  
metal vent connector cannot pass through any  
interior wall.  
ALL AIR FROM OUTDOORS USING HORIZONTAL DUCTS  
Figure 6.  
ALTERNATIVE  
OPENING  
LOCATION  
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.  
1 SQ. INCH  
PER 3000 BTUH  
100 SQ. INCH  
MINIMUM (EACH)  
CONFINED  
SPACE  
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.  
ALL AIR FROM OUTDOORS - USING A SINGLE PERMANENT OPENING  
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.  
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 efcient 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.  
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.  
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.  
The connector must be installed above the  
extreme bottom of the chimney to prevent  
potentially blocking the flue gases.  
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.  
9
COMBUSTION AIR AND VENT SYSTEM REQUIREMENTS  
The following gures are examples of vent pipe  
system installations and may or may not be typical  
for your specic application. Consult the “National  
Fuel Gas Code”, NFPA 54, ANSI Z223.1-current  
edition and the guidelines set forth by prevailing  
local codes.  
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  
2 FT. Minimum Above  
Any Object Within  
10 FT. Horizontally  
3 FT.  
Minimum  
2 FT. Minimum Above Any Object  
Support Strap  
3 FT.  
Within 10 FT. Horizontally  
Minimum  
Type B Double  
Wall Vent Pipe  
Maintain  
Clearance*  
Support Strap  
Seal  
Maintain  
Clearance*  
**Maintain  
Specified  
Clearance  
Do Not Extend  
Vent Beyond Edge  
Of Chimney  
Vent  
Connector  
Slope Up  
1/4 Inch  
Vent  
Connector  
Per Foot  
Minimum  
Slope Up  
1/4 Inch  
Per Foot  
Minimum  
Venting Gas Vent System With Type B Double Wall Vent Pipe.  
Figure 9.  
Chimney Termination Vent System  
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.  
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.  
Listed Vent Cap  
Maintain Manufacturer’s  
Specified Minimum Clearance  
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.  
**Maintain  
Specified  
Support Strap  
Clearance  
Seal  
Maintain  
Clearance*  
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.  
Vent Connector  
Vent  
Connector  
Slope Up  
Unused Chimney  
1/4 Inch  
Flue Or Masonry  
Per Foot  
Enclosure  
Minimum  
Gas vents must be supported to prevent damage,  
joint separation, and maintain clearances to  
combustible materials.  
Venting Through Chimney With Type B Double Wall Vent Pipe.  
IMPORTANT: This gas vent must be terminated in a  
vertical position to facilitate the removal of the burnt  
gases.  
Figure 10.  
An unused chimney ue or masonry enclosure  
may be used as a passageway for the installation  
of a gas vent. NOTE: The chimney ue 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.  
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.  
10