A O Smith 200 User Manual

COPPER BOILERS FOR  
HYDRONIC HEATING AND  
HOT WATER SUPPLY  
Installation  
Instruction Manual  
Operation  
GB/GW MODELS:  
1000, 1300, 1500, 1850, 2100, 2500  
SERIES 200, 201  
Maintenance  
Limited Warranty  
CAUTION  
TEXT PRINTED OR OUTLINED IN RED CONTAINS  
INFORMATION RELATIVE TO YOUR SAFETY.  
PLEASE READ THOROUGHLY BEFORE INSTALLING  
AND USING THIS APPLIANCE.  
u
o
WARNING: If the information in this  
manual is not followed exactly, a fire or  
explosion may result causing property  
damage, personal injury or loss of life.  
for buying this cost  
Thank Y  
efficient, high recovery unit from  
A. O. Smith Water Products Co.  
You should thoroughly read and understand this  
manual before installation and/or operation of this  
boiler. Please pay particular attention to the  
important safety and operating instructions as well  
as the WARNINGS and CAUTIONS.  
Do not store or use gasoline or other  
flammable vapors and liquids in the  
vicinity of this or any other appliance.  
WHAT TO DO IF YOU SMELL GAS:  
CONTENTS  
PAGE  
Extinguish any open flame.  
ROUGH-IN DIMENSIONS/CAPACITIES ............. 2 - 3  
FOREWORD ..................................................... 4 - 5  
FEATURES/CONTROLS ................................... 5 - 6  
INSTALLATION INSTRUCTIONS ................... 6 - 22  
VENTING ....................................................... 8 - 14  
SYSTEM INSTALLATION ..............................15 - 19  
HYDRONIC INSTALLATION ..........................15 - 17  
HOT WATER SUPPLY INSTALLATION .........17 - 19  
GAS CONNECTIONS ....................................20 - 21  
OPERATION ................................................ 22 - 23  
LIGHTINGANDOPERATING .........................24 - 25  
CONTROL SYSTEM .................................... 26 - 31  
PREVENTATIVE MAINTENANCE ................ 31 - 33  
TROUBLE SHOOTING ..................................33 - 34  
LIMITED WARRANTY .......................................... 35  
WIRING DIAGRAM/SCHEMATIC .................. 36 - 37  
Do not try to light any appliance.  
Do not touch any electrical switch; do  
not use any phone in your building.  
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.  
Installation and service must be  
performed by a qualified installer,  
service agency or the gas supplier.  
ADIVISION OFA. O. SMITH CORPORATION  
ELPASO, TX., MC BEE, SC., RENTON, WA.,  
STRATFORD-ONTARIO, VELDHOVEN-THE NETHERLANDS  
PLACE THESE INSTRUCTIONS ADJACENT TO BOILER AND  
NOTIFYOWNERTOKEEPFORFUTUREREFERENCE.  
PRINTED IN U.S.A. 2526 0501  
PART NO. 211257-000 REV. 0  
TABLE 3: RECOVERY CAPACITIES  
Input Rating  
Temperature Rise - Degrees °F (°C)  
50°F 60°F 70°F 80°F 90°F 100°F 110°F 120°F 130°F  
per Hr. (22.2°) (27.7°) (33.3°) (38.8°) (44.4°) (50°) (55.5°) (61.1°) (66.7°) (72.2°)  
Gal/Liter 40°F  
MODEL  
BTU/Hr. (kW)  
GW - 1000  
990,000 (290.1)  
LPH  
GPH  
LPH  
GPH  
LPH  
GPH  
LPH  
GPH  
LPH  
GPH  
LPH  
GPH  
9526 7620 6350 5443 4763 4234 3810 3462 3175 2930  
2520 2016 1680 1440 1260 1120 1008 916 840 775  
GW - 1300  
GW - 1500  
GW - 1850  
GW - 2100  
GW - 2500  
1,300,000 (380.9)  
1,500,000 (439.5)  
1,850,000 (542.0)  
2,100,000 (615.3)  
2,490,000 (729.6)  
12508 10006 8339 7148 6256 5560 5005 4547 4169 3848  
3309 2647 2206 1891 1655 1471 1324 1203 1103 1018  
14432 11548 9620 8248 7216 6415 5772 5247 4812 4442  
3818 3055 2545 2182 1909 1697 1527 1388 1273 1175  
17800 14239 11865 10172 8902 7912 7122 6471 5935 5477  
4709 3767 3139 2691 2355 2093 1884 1712 1570 1449  
20204 16163 13472 11548 10104 8981 8082 7348 6736 6218  
5345 4276 3564 3055 2673 2376 2138 1944 1782 1645  
23958 19168 15971 13691 11979 10648 9582 8713 7987 7371  
6338 5071 4225 3622 3169 2817 2535 2305 2113 1950  
TABLE 4: HEAT EXCHANGER PRESSURE DROP  
GB Models-Flow, Head Loss and Temperature Rise  
20 Deg. F Rise  
30 Deg. F Rise  
40 Deg. F Rise  
Maximum Flow Rate  
GPM PD-FT Deg. F  
Minimum Flow Rate  
GPM  
PD-FT  
Head  
GPM  
PD-FT  
Head  
GPM  
PD-FT  
Head  
GPM  
PD-FT  
Head  
Deg. F  
MODEL  
Head  
12.2  
Rise  
11  
Rise  
40  
GB - 1000  
83.16  
109.2  
126  
154  
n/a  
5.1  
7.2  
55.4  
72.8  
84  
2.7  
4.2  
41.6  
54.6  
63  
1.5  
3.2  
4.3  
6.4  
8.3  
11.6  
154  
154  
154  
154  
154  
154  
42  
55  
1.5  
3.2  
4.3  
6.4  
8.3  
11.6  
GB - 1300  
GB - 1500  
GB - 1850  
GB - 2100  
GB - 2500  
14.5  
16.3  
18.5  
21.3  
23.2  
14  
17  
20  
23  
28  
40  
40  
40  
40  
40  
10.1  
18.5  
n/a  
6.3  
64  
103.6  
117.6  
139.4  
10.1  
14.5  
18.5  
77.7  
88.2  
104.6  
78  
89  
n/a  
n/a  
105  
Note: GW models (GB optional) are equipped with pumps capable of handling 50 equivalent feet  
(15.2 m) of normal pipe fittings.  
3
PRECAUTIONS  
FOREWORD  
IF THE UNIT IS EXPOSED TO THE FOLLOWING, DO NOT  
OPERATE UNTIL ALL CORRECTIVE STEPS HAVE BEEN MADE  
BY A QUALIFIED SERVICEMAN:  
These designs comply with the latest edition of the American  
National Standards for Gas-Fired, Low-Pressure Steam and Hot  
Water Boilers, ANSI Z21.13 and CGA 4.9/CGA 3.3 latest edition, as  
a low pressure boiler.  
1. EXPOSURE TO FIRE.  
2. IF DAMAGED.  
3. FIRING WITHOUT WATER.  
4. SOOTING.  
Detailed installation diagrams are found in this manual. These  
diagrams will serve to provide the installer a reference for the  
materials and methods of piping necessary. It is essential that all  
water, gas piping and wiring be installed as shown on the diagrams.  
You should thoroughly read and understand this manual before  
installation and/or operation of this boiler.  
IF THE BOILER HAS BEEN EXPOSED TO FLOODING, IT MUST BE  
REPLACED.  
LIQUID PETROLEUM MODELS  
The factory warranty will be void if the boiler(s) have been improperly  
installed or operated.  
Boilers for propane or liquefied petroleum gas (LPG) are different  
from natural gas models. A natural gas boiler will not function  
safely on LP gas and no attempt should be made to convert a  
boiler from natural gas to LP gas.  
In addition to these instructions, the boiler(s) shall be installed in  
accordance with those installation regulations in force in the local  
area where the installation is to be made. These shall be carefully  
followed in all cases. Authorities having jurisdiction should be  
consulted before installations are made.  
LP gas must be used with great caution. It is highly explosive and  
heavier than air. It collects first in the low areas making its odor  
difficult to detect at nose level. If LP gas is present or even  
suspected, do not attempt to find the cause yourself. Leave the  
building, leaving doors open to ventilate, then call your gas supplier  
or service agent. Keep area clear until a service call has been  
In the absence of local codes, the installation must comply with  
the latest editions.  
In the United States:  
The National Fuel Gas Code,ANSI Z223.1/NFPA54 and the National made.  
Electric Code, NFPA 70.  
At times you may not be able to smell an LP gas leak. One cause  
In Canada:  
is odor fade, which is a loss of the chemical odorant that gives LP  
gas its distinctive smell. Another cause can be your physical  
condition, such as having a cold or diminishing sense of smell  
with age. For these reasons, the use of a propane gas detector is  
recommended.  
The installation Code CAN/CSA B149.1 and .2 (latest edition) and  
the Canadian Electric Code, CSA C22.2.  
These are available from the Canadian Standards Association,  
8501 East Pleasant Valley Road, Cleveland, OH 44131, USA, or,  
Canadian Gas Association Laboratories, 55 Scarsdale Road, Don  
Mills, Ontario M3B 2R3, Canada.  
IF YOU EXPERIENCEAN OUT OF GAS SITUATION, DO NOT TRY  
TO RELIGHT APPLIANCES YOURSELF. Call your local service  
agent. Only trained LP professionals should conduct the required  
safety checks in accordance with industry standards.  
GROUNDING INSTRUCTIONS  
This boiler must be grounded in accordance with the National  
Electrical Code and/or local codes. Boiler is polarity sensitive,  
correct wiring is imperative for proper operation.  
HIGHALTITUDE INSTALLATION  
WARNING  
INSTALLATIONS ABOVE 4,500 FEET REQUIRE REPLACEMENT  
OF THE BURNER ORIFICES IN ACCORDANCE WITH THE  
NATIONAL FUEL GAS CODE (ANSI/NFPA 54). FAILURE TO  
REPLACE THE ORIFICES WILL RESULT IN IMPROPER AND  
INEFFICIENT OPERATION OF THE APPLIANCE, PRODUCING  
CARBON MONOXIDE GAS IN EXCESS OF SAFE LIMITS, WHICH  
COULD RESULT IN SERIOUS PERSONAL INJURY OR DEATH.  
This boiler must be connected to a grounded metal, permanent  
wiring system, or an equipment grounding conductor must be run  
with the circuit conductors and connected to the equipment  
grounding terminal or lead on the boiler.  
WARNING  
YOUR BOILER IS NOT DESIGNED TO OPERATE WITHABOILER  
INLET WATER TEMPERATURE OF LESS THAN 120°F (38°C).  
COLDER INLET WATER TEMPERATURE WILL RESULT IN  
SIGNIFICANT CONDENSATION DEVELOPING ON THE HEAT  
EXCHANGER. THIS SITUATION CAN CAUSE A CORROSIVE  
ENVIRONMENT FOR THE HEAT EXCHANGER, BURNERS AND  
VENTING RESULTING IN PREMATURE DAMAGE, WHICH COULD  
RESULT IN SERIOUS PERSONAL INJURY OR DEATH.  
GENESIS BOILERS ARE EQUIPPED WITH SELF-REGULATING  
PREJET ORIFICES WHICHAUTOMATICALLY COMPENSATE FOR  
HIGHER ELEVATIONS AND ADJUST THE APPLIANCE'S INPUT  
RATEACCORDINGLY, MAKING IT UNNECESSARY TO REPLACE  
ORIFICES FOR HIGH ALTITUDE (UP TO 4,500 FEET ONLY.  
CONSULT THE FACTORY FOR HIGHERALTITUDES.)  
FOR SYSTEMS THAT USE LARGE VOLUMES OF COLD WATER Some utility companies derate their gas for altitude. You should  
OR SYSTEMS UTILIZING HEAVY WATER DRAWS, CONDENSATION  
CAN BE PREVENTED BY USINGABYPASS LOOP.  
contact your gas supplier for any specific changes which may be  
required in your area. Call the local gas utility to verify BTU content  
of the gas supplied.  
CORRECT GAS  
Ratings specified by manufacturers for most boilers apply for  
elevations up to 4,500 feet (1350 m). For elevations above 4,500  
feet (1350 m) ratings must be reduced by a rate of 4% for each  
1,000 feet (300 m) above sea level.  
Make sure the gas on which the boiler will operate is the same as  
that specified on the boiler rating plate. Do not install the boiler if  
equipped for a different type of gas, consult your gas supplier.  
4
Example: A Genesis boiler is rated at 1,300,000 Btu/hr. input at sea  
level. At an altitude of 5,000 (1500m), the prejet orifices will decrease  
the input rate by 20% (= 4% x 5) to a new rating of 1,040,000 Btu/hr.  
FLAME SENSOR  
The flame sensor acts to prove the flame has carried over from the  
(= 80% x 1,300,000 Btu/hr.) The input reduction is achieved by the ignitor to the right-most burner. If no flame is sensed, the gas  
valve(s) will close automatically. If no flame is sensed on three  
ignition trials the boiler will lock out. Upon lockout, manually push  
the ENTER/RESET button on the display panel to restart the boiler.  
prejet orifices through self-regulation.  
FEATURES/CONTROLS  
WATER FLOW SWITCH  
MULTI-STAGE FIRINGAND CONTROL SYSTEM  
The Water Flow Switch is installed at the boiler outlet to prevent  
burner operation in the event of inadequate water flow through the  
boiler. The Water Flow Switch is a single pole, normally open  
switch that will close its contacts when increasing water flow rate  
is encountered. This switch is factory-set, but may require field  
adjustment. The contacts will open when the flow rate drops below  
the adjusted setting and the gas valve(s) will close turning off the  
gas to the burners.  
ALL MODELS - The control system consists of three basic  
components: 1) Central Control Board 2) Ignition Control Board  
and 3) Display Board. The Central Control Board and Ignition  
Control Boards are located in the control box and can be accessed  
through panels on the left side and top of the unit. The Display  
Board is attached to the front jacket panel. The control system is a  
multi-stage control capable of managing three or four ignition  
stages. Three stage models include the 1000, 1300 and 1500.  
Four stage models include the 1850, 2100 and 2500. Every system  
will have one Central Control Board, one Display Board and either  
three or four Ignition Control Boards depending on the model.  
There will be one Ignition Control Board per stage.  
LIMIT CONTROLS  
CAUTION  
LIMIT CONTROLS ARE SAFETY DEVICES AND ARE NOT TO BE  
USEDASATHERMOSTAT.  
The central control board contains a strip of dip switches which  
allow the user to control several system variables. Table 5 shows  
a summary of these options. Make sure the dip switches are in  
the appropriate position for the unit's application. Consult the  
Control System section of the manual for more information, see  
page 26.  
The GB/GW models incorporate an outlet water probe consisting  
of two limit controls:  
1. An adjustable automatic reset limit control, that can be set to  
either 210°F (99°C) or 240°F (115°C) depending on the  
application.  
2. A fixed manual reset limit factory set at 250°F (121°C). If the  
manual reset should open due to high temperature the gas  
valves will close and the unit will go into lockout.  
DIP SWITCH CONFIGURATION TABLE  
SW1 OFF  
ON  
SELECTION:  
EITHER 3 OR 4 STAGE SYSTEM  
EITHER 3 OR 1  
WHETHER SYSTEM IS IRI OR  
STANDARD  
INLET OR TANKAS  
CONTROLLINGPROBE  
WHETHEREXTERNAL  
A
B
C
3 STAGE  
3 TRIALS  
NOIRI  
4 STAGE  
1 TRIAL  
IRI  
If lockout occurs, manually push the ENTER/RESET  
push-button on the display panel to restart the boiler.  
GAS VALVE GAS VALVE  
INLET TANK  
D
E
ON/OFF SWITCH  
NO EXTERNAL EXTERNAL  
THERMOSTAT THERMOSTAT THERMOSTATIS USED  
OUTLET 210°F OUTLET 240°F OUTLETMAXIMUMTEMPERATURE  
The ON/OFF switch is a single-pole, single-throw rocker switch.  
The switch provides 120VAC from the line source to the boiler.  
F
G
H
190°F  
220°F  
MAX. SET-POINTTEMPERATURE  
EITHER °F OR °C FOR DISPLAYED  
TEMPERATURE  
DEGREES°F DEGREES°C  
COMBUSTION AIR BLOWER  
Provides air for combustion process. The blower settings are  
adjustable through the use of the air shutter, however, blowers are  
set at the factory and should not need adjustment.  
Figure 2. Summary of Dip Switch Options.  
DIFFERENTIAL PRESSURE SWITCH  
TANK PROBE  
The differential pressure switch ensures that a sufficient differential  
exists between the air pressure in the pre-mix chamber and the  
inlet of the burner for safe, low NOX combustion. The switch has  
two pressure taps marked "+" (positive) and "-" (negative). Silicone  
tubing is run from the positive pressure tap of the switch to a tap on  
the control panel to measure the air pressure in the pre-mix  
chamber. The negative pressure tap measures the pressure taken  
at the burner's auxiliary tube. Connections can be seen by removing  
the lower front jacket panel. It is important that this panel remain  
sealed at all times while the boiler is operating.  
FOR HOT WATER SUPPLY SYSTEMS (GW models),Atank probe is  
supplied with each hot water supply boiler. The inlet water  
temperature will default to the tank temperature on the display when  
the tank probe is installed.  
Note: Tank Probe must be designated as controlling probe using  
Dip Switch "D" on Central Control Board before it can be used for  
(GW) hot water supply applications.  
"Pigtails" of field-supplied wires should be spliced to "pigtails" of  
tank probe and connected to terminal block in the 24 volt junction  
box. See figure 12 for the tank probe installation. Follow the  
instructions for the operation and temperature setting procedures  
for the tank probe (see page 29).  
This differential pressure switch is normally open and closes when  
the combustion blower starts.  
BLOCKED FLUE PRESSURE SWITCH  
The blocked flue pressure switch ensures that the flue gas vent is  
clear. This pressure switch is normally closed and only opens on  
the fault conditions.  
FOR HOT WATER HEATING SYSTEMS (GB models) Due to the  
many various types of systems and operating conditions, a tank  
5
probe is not supplied with the GB models. A tank probe can be  
used as an option to control loop temperature and unit staging.  
Additionally, the Inlet Temperature Probe can be used as the loop  
thermostat in some heating (GB) applications. These types of  
controls connect to designated wires in the junction box at the rear  
of the boiler. Do not operate this boiler using the internal high  
limits only, you must use an operating thermostat as mentioned  
above.  
If any safety relief valve is replaced, the replacement valve must  
comply with the latest version of the ASME Boiler and Pressure  
Vessel Code, Section IV (HEATING BOILERS). Select a relief valve  
with a discharge rating NOT less than the boiler input, and a set  
pressure NOT exceeding the working pressure of any component  
in the system.  
The storage tank temperature and pressure relief valve must  
comply with the applicable construction provisions of the Standard  
for Relief Valves and Automatic Gas Shut-off Devices for Hot Water  
Supply Systems, ANSI Z21.22 or CSA-4.4 (and latest addendums).  
The valve must be of the automatic reset type and not embody a  
single-use type fusible plug, cartridge or linkage.  
Note: Additional 24V devices or Tank Probe must be identified  
using Dip Switches on Central Control Board before they are  
recognized as a part of the heating system. See table 5 and refer to  
"Multi-Stage Firing and Control System" on previous page for more  
information about dip switch settings.  
CIRCULATING PUMP  
FOR HOT WATER HEATING SYSTEMS, the boilers are shipped  
with a 50 psi pressure relief valve. This relief valve is factory  
installed in the water outlet header of the boiler, see figure 1.  
The pump flow rate should not exceed the maximum  
recommended flow rate, see table 4.  
FOR HOT WATER SUPPLY SYSTEMS, the boilers are shipped  
with a 125 psi pressure relief valve. This relief valve is factory  
installed in the water outlet header of the boiler, see figure 1.  
FOR HOT WATER SUPPLY SYSTEMS (GW models), ordered with  
the circulator as an integral part of the boiler; the pump has been  
lubricated at the factory, and future lubrication should be in  
accordance with the motor manufacturer's instructions provided  
as supplement to this manual.  
This ASME-rated valve has a discharge capacity that exceeds the  
maximum boiler input rating and a pressure rating that does not  
exceed the maximum working pressure shown on the boiler rating  
plate.  
FOR HOT WATER HEATING SYSTEMS (GB models or GW models  
ordered without circulator), the circulator is NOT provided and  
must be field-installed.  
In addition, an A.G.A. design-certified and ASME-rated temperature  
and pressure (T & P) relief valve must be installed on each and  
every water storage tank in the hot water supply system, see  
figures 11 and 13.  
LOW WATER CUTOFF (Not Supplied)  
If low water protection is required by the authorities having  
jurisdiction, a low water cutoff switch should be installed  
next to the boiler in the outlet water line as shown in  
"HYDRONIC INSTALLATION" section. The switch should receive  
periodic (every six months) inspection to assure proper operation.  
A low water cutoff device of the float type should be flushed every six  
months.  
The T & P relief valve should have a temperature rating of 210°F  
(99°C), a pressure rating NOT exceeding the lowest rated working  
pressure of any system component, and a discharge capacity  
exceeding the total input of the water boilers supplying water to the  
storage tank.  
DRAIN VALVE (Not Supplied)  
Locate the T & P relief valve (a) in the top of the tank, or (b) in the  
side of the tank on a center line within the upper six (6) inches  
(15 cm) of the top of the tank. The tapping shall be threaded in  
accordance with the latest edition of the Standard for Pipe Threads,  
General Purpose (inch), ANSI/ASME B1.20.1. The location of, or  
intended location for, the T & P relief valve shall be readily  
accessible for servicing or replacement.  
Additional drain valves must be obtained and installed on each  
boiler and tank for draining purposes.  
SAFETY RELIEF VALVES  
Your local code authority may have other specific relief valve  
requirements not covered below.  
INSTALLATION INSTRUCTIONS  
WARNING  
THE PURPOSE OF A SAFETY RELIEF VALVE IS TO AVOID  
EXCESSIVE PRESSURE WHICH MAY CAUSE TANK EXPLOSION,  
SYSTEM OR BOILER DAMAGE.  
REQUIRED ABILITY  
INSTALLATION OR SERVICE OF THIS BOILER REQUIRESABILITY  
EQUIVALENT TO THAT OF A LICENSED TRADESMAN IN THE  
FIELD INVOLVED. PLUMBING, AIR SUPPLY, VENTING, GAS  
SUPPLY AND ELECTRICAL WORK ARE REQUIRED.  
TOAVOID WATER DAMAGEADRAIN LINE MUST BE CONNECTED  
TOASAFETY RELIEF VALVE TO DIRECT DISCHARGE TOASAFE  
LOCATION. A DRAIN LINE MUST NOT BE REDUCED FROM THE  
SIZE OF THE VALVE OUTLET AND IT MUST NOT CONTAIN ANY  
VALVES BETWEEN THE BOILERAND THE RELIEF VALVE OR THE  
RELIEF VALVE AND THE DRAIN EXIT. IN ADDITION, THERE  
SHOULD NOT BE ANY RESTRICTIONS IN A DRAIN LINE NOR  
SHOULD IT BE ROUTED THROUGH AREAS WHERE FREEZING  
CONDITIONS MIGHT OCCUR. DO NOT THREAD OR CAP THE  
DRAIN LINE EXIT. RESTRICTING OR BLOCKING A DRAIN LINE  
WILL DEFEAT THE PURPOSE OF THE RELIEF VALVE AND MAY  
CREATEAN UNSAFE CONDITION. INSTALLADRAIN LINE WITH  
A DOWNWARD SLOPE SUCH THAT IT NATURALLY DRAINS  
ITSELF.  
LOCATION  
When installing the boiler, consideration must be given to proper  
location. Location selected should be as close to the stack or  
chimney as practical with adequate air supply and as centralized  
with the piping system as possible. This location should also be  
such that the gas ignition system components are protected from  
water (dripping, spraying, etc.) during appliance operation and  
service (circulator replacement, control replacement, etc.)  
6
THE BOILER MUST NOT BE INSTALLED ON CARPETING.  
THE BOILER SHOULD NOT BE LOCATED INANAREAWHERE  
IT WILL BE SUBJECT TO FREEZING.  
THE BOILER SHOULD BE LOCATED NEAR A FLOOR DRAIN.  
THE BOILER SHOULD BE LOCATED IN AN AREA WHERE  
LEAKAGE FROM THE BOILER OR CONNECTIONS WILL NOT  
RESULT IN DAMAGE TO THEADJACENTAREAOR TO LOWER  
FLOORS OF THE STRUCTURE.  
INSTALLATION CLEARANCES  
Sufficient area should be provided at the front and sides of the  
unit for proper servicing. For ease of service, minimum  
clearances of 24" (61.0 cm) in the front and 18" (46.0 cm) on  
the sides are recommended. It is important that the minimum  
clearances be observed to allow service to the control box and  
other controls. Observing proper clearances will allow service  
to be performed without movement or removal of the boiler from  
its installed location. Failure to observe minimum clearances  
may require removal of the boiler in order to service such items as  
the heat exchanger and burners. In a utility room installation, the  
door shall be wide enough to allow the boiler to enter or to permit  
the replacement of another appliance.  
WHEN SUCH LOCATIONS CANNOT BE AVOIDED, A SUITABLE  
DRAIN PAN SHOULD BE INSTALLED UNDER THE BOILER. Such  
pans should be fabricated with sides at least 2-1/2" (6.5 cm) deep,  
with length and width at least 2" (5.1 cm) greater than the dimensions  
of the boiler and must be piped to an adequate drain. The pan  
must not restrict combustion air flow.  
Two inch (5.1 cm) clearance is allowable from combustible  
construction to hot water pipes. Sufficient clearance should be  
provided at one end of the boiler to permit access to heat exchanger  
tubes for cleaning.  
WARNING  
THERE IS A RISK IN USING FUEL BURNING APPLIANCES IN  
ROOMS OR AREAS WHERE GASOLINE, OTHER FLAMMABLE  
LIQUIDS OR ENGINE DRIVEN EQUIPMENT OR VEHICLES ARE  
STORED, OPERATED OR REPAIRED. FLAMMABLE VAPORSARE  
HEAVYAND TRAVELALONG THE FLOOR AND MAY BE IGNITED  
BY THE IGNITER OR MAIN BURNER FLAMES CAUSING FIRE OR  
EXPLOSION. SOME LOCALCODES PERMIT OPERATION OF GAS  
APPLIANCES IF INSTALLED 18 INCHES (46.0 CM) OR MORE  
ABOVE THE FLOOR. THIS MAY REDUCE THE RISK IF LOCATION  
IN SUCHAN AREA CANNOT BE AVOIDED.  
Access to control box items such as the Central Control Board,  
Ignition Control Boards and wiring harnesses is provided through  
a panel on the left side of the unit. An 18" (46.0 cm) minimum  
clearance is recommended.  
These boilers are approved for installation on noncombustible  
flooring in an alcove with minimum clearance to combustibles of:  
3 inches (7.6 cm) Right Side, and Back; 6 inches (15.2 cm) Top,  
Front Alcove, 12 inches (30.5 cm) Left Side and 6 inches (15.2 cm)  
Vent.  
FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY  
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST NEVER  
BE PLACED ON OR ADJACENT TO THE BOILER.  
For installation on combustible flooring use the Combustible Floor  
Kit. The combustible floor kit base adds 4" (10.1 cm) to the overall  
height of the boiler. See figure 3.  
OPEN CONTAINERS OF FLAMMABLE MATERIAL SHOULD NOT  
BE STORED OR USED IN THE SAME ROOM WITH THE BOILER.  
If the boiler is installed above the level of heating system terminal  
units, a low water cutoff device must be installed in the boiler outlet  
at the time of installation.  
For installation locations with elevations above 4,500 feet  
(1350 m), consult the factory.  
WARNING  
UNDER NO CIRCUMSTANCES SHOULD THE EQUIPMENT ROOM  
WHERE THE BOILER IS INSTALLED EVER BE UNDER NEGATIVE  
PRESSURE. PARTICULAR CARE MUST BE TAKEN WHEN  
EXHAUST FANS, COMPRESSORS,AIR HANDLING EQUIPMENT,  
ETC., MAY INTERFERE WITH THE COMBUSTION AND  
VENTILATIONAIR SUPPLIES OF THIS BOILER.  
MODEL  
COMBUSTIBLE FLOOR KIT NO.  
211093  
(GB/GW)-1000  
(GB/GW)-1300  
(GB/GW)-1500  
(GB/GW)-1850  
(GB/GW)-2100  
(GB/GW)-2500  
211093-1  
211093-2  
CHEMICAL VAPOR CORROSION  
211093-3  
211093-4  
Heat exchanger corrosion and component failure can be caused  
by the heating and breakdown of airborne chemical vapors. Spray  
can propellants, cleaning solvents, refrigerator and air conditioning  
refrigerants, swimming pool chemicals, calcium and sodium  
chloride, waxes, and process chemicals are typical compounds  
which are corrosive. These materials are corrosive at very low  
concentration levels with little or no odor to reveal their presence.  
211093-5  
Figure 3: Boiler on Combustible Floor Base and Kit Numbers  
LEVELLING  
Each unit must be checked after installation to be certain that it is  
level.  
Products of this sort should not be stored near the boiler. Also, air  
which is brought in contact with the boiler should not contain any of  
these chemicals. If necessary, uncontaminated air should be  
obtained from remote or outside sources. Failure to observe this  
requirement will void the warranty.  
AIR REQUIREMENTS  
WARNING  
FOR SAFE OPERATION, AN AMPLE SUPPLY OF AIR MUST BE  
7
PROVIDED FOR PROPER COMBUSTION AND VENTILATION IN sufficient openings for air must be provided in the walls.  
ACCORDANCE WITH THE NATIONAL FUEL GAS CODE, ANSI  
Z223.1 OR CAN/CSA-B149.1 AND .2 (LATEST EDITIONS) OR  
APPLICABLE PROVISIONS OF THE LOCAL BUILDING CODES.  
AN INSUFFICIENT SUPPLY OF AIR MAY RESULT IN A YELLOW,  
LUMINOUS BURNER FLAME, CARBONING OR SOOTING OF THE  
FINNED HEAT EXCHANGER, OR CREATE A RISK OF  
ASPHYXIATION. DO NOT OBSTRUCT THE FLOW OF  
COMBUSTIONAND VENTILATIONAIR.  
UNDERSIZED OPENINGS WILL CAUSE AIR TO BE DRAWN INTO  
THE ROOM THROUGH THE CHIMNEY, CAUSING POOR  
COMBUSTION. SOOTING MAY RESULT WITH AN INCREASED  
RISK OFASPHYXIATION.  
VENTING  
This boiler is approved to be vented as a Category I, Category III  
!
(horizontal venting), or a Direct Vent appliance. The Horizontal and  
Direct Venting options require a special vent kit.  
UNCONFINED SPACE  
In buildings of conventional frame, brick or stone construction,  
unconfined spaces may provide adequate air for combustion.  
TABLE 6: DIRECT VENT KITS  
Horiz. or Horiz. Direct Vent Kit No.  
211090  
Model Number  
G(W,B) 1000  
G(W,B) 1300  
G(W,B) 1500  
G(W,B) 1850  
G(W,B) 2100  
G(W,B) 2500  
Model Number  
G(W,B) 1000  
G(W,B) 1300  
G(W,B) 1500  
G(W,B) 1850  
G(W,B) 2100  
G(W,B) 2500  
If the unconfined space is within a building of tight construction  
(buildings using the following construction: weather stripping, heavy  
insulation, caulking, vapor barrier, etc.), air for combustion,  
ventilation, must be obtained from outdoors or spaces freely  
communicating with the outdoors. The installation instructions for  
confined spaces in tightly constructed buildings must be followed  
to ensure adequate air supply.  
211090-1  
211090-1  
211090-4  
211090-2  
211090-3  
Vertical Direct Vent Kit No.  
211089  
CONFINED SPACE  
211089-1  
211089-1  
211089-4  
211089-2  
(a) U. S. INSTALLATIONS  
When drawing combustion and dilution air from inside a  
conventionally constructed building to a confined space, such a  
space shall be provided with two permanent openings, ONE  
WITHIN 12 INCHES OF THE ENCLOSURE TOP AND ONE WITHIN  
12 INCHES OF THE ENCLOSURE BOTTOM. Each opening shall  
have a free area of at least one square inch per 1000 Btuh of the  
total input of all appliances in the enclosure, but not less than 100  
square inches.  
211089-3  
CAUTION  
WHEN VENTING THE GENESIS BOILER THROUGH AN  
OVERSIZED CHIMNEY (INCLUDING MASONRY CHIMNEYS),  
ADDITIONAL CARE MUST BE EXERCISED TO ASSURE PROPER  
DRAFT. FOR PROPER OPERATION,AMINIMUM DRAFT OF -0.02"  
W.C.ANDAMAXIMUM DRAFTOF -0.04" W.C. MUSTBE MAINTAINED.  
IN INSTANCES OF EXCESSIVE DRAFT,ABAROMETRIC DAMPER  
MAY BE REQUIRED TO ASSIST IN MAINTAINING THE PROPER  
DRAFT. DRAFT SHOULD BE MEASURED 2 FEET (0.6 M)ABOVE  
THE BOILER VENT COLLAR.  
If the confined space is within a building of tight construction, air for  
combustion, ventilation, and draft hood dilution must be obtained  
from outdoors. When directly communicating with the outdoors or  
communicating with the outdoors through vertical ducts, two  
permanent openings, located in the above manner, shall be  
provided. Each opening shall have a free area of not less than one  
square inch per 4000 Btuh of the total input of all appliances in the  
enclosure. If horizontal ducts are used, each opening shall have a  
free area of not less than one square inch per 2000 Btuh of the total  
input of all appliances in the enclosure.  
WARNING  
THE INSTRUCTIONS IN THIS SECTION ON VENTING THE BOILER  
MUST BE FOLLOWED TO AVOID CHOKED COMBUSTION OR  
RECIRCULATION OF FLUE GASES. SUCH CONDITIONS CAUSE  
SOOTING OR RISKS OF FIREANDASPHYXIATION.  
(b) CANADIAN INSTALLATIONS  
CONNECTING BOILER TO A COMMON VENT  
Ventilation of the space occupied by the boiler(s) shall be provided  
by an opening for ventilation air at the highest practical point  
communicating with outdoors. The total cross- sectional area shall  
be at least 10% of the area of the combustion air opening but in no  
case shall the cross-sectional area be less than 10 square inches  
(6500 mm2).  
Do not connect the boiler to a common vent or chimney with solid  
fuel burning equipment. This practice is prohibited by most local  
building codes as is the practice of venting gas fired equipment to  
the duct work of ventilation systems.  
Where a separate vent connection is not available and the vent  
pipe from the boiler must be connected to a common vent with an  
oil burning furnace, the vent pipe should enter the common vent or  
chimney at a point ABOVE the flue pipe from the oil furnace.  
In addition to the above, there shall be permanent air supply  
opening(s) having a cross-sectional area of not less than 1 square  
inch per 7,000 BTUH (310 mm2/KW) up to and including 1,000,000  
BTUH plus 1 square inch per 14,000 BTU in excess of 1,000,000  
BTUH. This opening(s) shall be located at, or ducted to, a point  
neither more than 18" (46.0 cm) nor less than 6 inches (15.2 cm)  
above the floor level.  
UL/ULC listed double wall type B-1 gas vents, through 16" diameter,  
can be installed in heated and unheated areas and can pass  
through floors, ceilings, partitions, walls and roofs, provided the  
required clearance is observed.  
Where power vented equipment is used in the same room as the  
boiler, sufficient air openings must be supplied. UNDERSIZED At the time of removal of an existing boiler, the following steps shall  
be followed with each appliance remaining connected to the  
common venting system. Perform these steps while the other  
appliances remaining connected to the common venting system  
are not in operation.  
OPENINGS MAY RESULT IN INSUFFICIENT AIR FOR  
COMBUSTION.  
Where an exhaust fan is installed in the same room with a boiler,  
8
LOCATION REQUIREMENTS (INTAKE/EXHAUST)  
1. Seal any unused opening in the common venting system.  
2. Visually inspect the venting system for proper size and horizontal  
pitch and determine there is no blockage or restriction, leakage,  
corrosion or other unsafe condition.  
3. Isolate the space containing the appliance(s) remaining  
connected to the common venting system as much as possible  
by closing all openings (windows, doors, etc.) connected to  
other spaces in the building. Turn on any exhaust fans to their  
maximum setting and close fireplace dampers. Note: DO NOT  
operate summer exhaust fan.  
4. Test fire the appliance(s) being inspected, making sure to follow  
the manufacturers lighting and operating instructions.  
Appliance(s) operating controls should be adjusted to provide  
continuous service.  
5. Check vent pressure of appliance 24 inches (61.0 cm) above  
boiler vent collar. Vent pressure should be maintained between  
-0.02" W. C. and -0.04" W.C. to assure proper operation. For  
appliances with a draft hood, check for spillage with mirror,  
smoke or other device five minutes after placing appliance in  
operation.  
Intake/Exhaust Installation Requirements (See figure 4):  
1. The termination must be 12 inches (30.5 cm) above snow or  
grade level whichever is higher.  
2. Due to normal formation of water vapor in the combustion  
process, horizontal terminations must not be located over areas  
of pedestrian or vehicular traffic, i.e. public walkways or over  
areas where condensate could create a nuisance or hazard.  
This is especially true in colder climates where ice buildup is  
likely to occur. A.O. Smith Corporation will not be held liable for  
any personal injury or property damage due to any dislodging  
of ice.  
3. The minimum distance for any window, gravity air inlet to a  
building, or from gas or electric meter(s) is 6 feet (1.8 m)  
horizontally, 4 feet (1.2 m) below and 24 inches (61.0 cm) above.  
4. The minimum distance from inside corner formed by two  
exterior walls is 6 feet (1.8 m) but 10 feet (3.1 m) is  
recommended where possible.  
5. Maintain a minimum distance of 4 feet (1.2 m) from any soffit or eve  
vent to the exhaust terminal.  
6. Maintain a minimum distance of 10 feet (3.1 m) from any forced  
air inlet to a building. Any fresh air or make up air inlet such as  
a dryer or furnace area is considered to be a forced air inlet.  
6. After it has been determined that each appliance remaining  
connected to the common venting system properly vents when  
tested as outlined above, return doors, windows, exhaust fans, 7. Avoid areas where condensate drainage may cause problems  
such as above planters, patios, or adjacent to windows where  
the steam from the flue gases may cause fogging.  
8. Select the point of wall penetration where the minimum 1/4" per  
foot (2 cm/m) of slope up can be maintained.  
9. The through the wall termination kit is suitable for zero clearance  
to combustible materials.  
fireplace dampers and other gas burning appliances to their  
previous conditions of use.  
All boiler venting systems shall be installed in accordance with the  
National Fuel Gas Code, ANSI Z223.1 or CAN/CSA-B149.1 and .2  
(and latest addendums), or applicable provisions of the local  
building codes.  
10.The mid point of the termination elbow must be a minimum of  
12 inches (30.5 cm) from the exterior wall.  
CAUTION  
Direct venting into dead air spaces such as alleys, atriums and  
inside corners can cause recirculation of flue gases.  
Recirculation of flue gases will cause sooting, premature failure  
of the heat exchanger and icing of the combustion air intake  
during severe cold weather. To prevent the recirculation of flue  
gases, maintain as much distance as possible between the  
combustion air intake and the exhaust vent terminal.  
Figure 4. Vent Termination Installation Clearances  
9
STANDARD VENT - VERTICAL (CATEGORY I)  
IMP
VENT PRESSUR
BETWEEN -0.02" W
(61.0 cm) ABO
Figure 5.  
TABLE 7. STANDARD VERTICAL VENTING (CATEGORY I)  
APPLIANCE  
CATEGORY  
CERTIFIED  
VENTING  
MATERIAL  
EXHAUST  
VENT SIZE  
(INCHES)  
MAXIMUM LENGTH WITHOUT  
BAROMETRIC DAMPER (FEET)  
MODEL  
I000  
TYPE B OR  
EQUIVALENT  
10”(25.4 cm)  
35 Feet (10.7 m) without damper  
*70 Feet (21.3 m) max. with damper  
I
I
I
I
1300  
1500  
TYPE B OR  
EQUIVALENT  
35 Feet (10.7 m) without damper  
*70 Feet (21.3 m) max. with damper  
12" (30.5 cm)  
14"(35.6 cm)  
1850  
2100  
TYPE B OR  
EQUIVALENT  
35 Feet (10.7 m) without damper  
*70 Feet (21.3 m) max. with damper  
TYPE B OR  
EQUIVALENT  
16" (40.6 cm)  
35 Feet (10.7 m) without damper  
*70 Feet (21.3 m) max. with damper  
2500  
* Extending venting over 70 feet (21.3 m) may require special considerations.  
• Connection for the appliance exhaust vent to the stack must be as direct as possible. Maximum and minimum venting length  
for Category I appliances shall be determined per the latest edition of the National Fuel Code (U.S.) and CAN/CSA-B149.1  
and .2 Installation Code (Canada).  
• The horizontal breaching of a vent must have an upward slope of not less than 1/4 inch per linear foot (2 cm/m) from the boiler  
to the vent terminal. The horizontal portion of the vent shall be supported to maintain clearances and to prevent physical damage  
or separation of joints.  
10  
STANDARD VENT - HORIZONTAL (CATEGORY III)  
Figure 6.  
TABLE 8. STANDARD HORIZONTAL VENTING (CATEGORY III)  
APPLIANCE  
CATEGORY  
CERTIFIED  
VENTING  
MATERIAL  
EXHAUST  
VENT SIZE  
(INCHES)  
MAXIMUM  
VENT LENGTH  
(FEET)  
MODEL  
I000  
STAINLESS  
STEEL  
III  
III  
III  
III  
70' (21.3 m)  
70' (21.3 m)  
70' (21.3 m)  
70' (21.3 m)  
10”(25.4 cm)  
12" (30.5 cm)  
1300  
1500  
STAINLESS  
STEEL  
1850  
2100  
STAINLESS  
STEEL  
14"(35.6 cm)  
16" (40.6 cm)  
STAINLESS  
STEEL  
2500  
WARNING: No substitutions of flue pipe or vent cap material are allowed. Such substitutions would jeopardize the  
safety and health of inhabitants.  
• A maximum of two elbows can be used on inlet and outlet vent piping respectively. Each elbow is equal to 10 feet (3 m) of  
straight pipe.  
• Use only special gas vent pipes listed for use with Category III gas burning heaters, such as stainless steel Saf-T-Vent  
by Heat Fab, Inc., available from A.O. Smith WPC, 5621 W. 115th Street, Alsip, IL 60803 Phone: 1-800-433-2545 or  
Fax: 1-800-433-2515. Pipe joints must be positively sealed.  
11  
DIRECT VENT - VERTICAL (CATEGORY I)  
Figure 7.  
TABLE 9. DIRECT VENT (VERTICALEXHAUST CONFIGURATIONS)  
APPLIANCE  
CERTIFIED  
EXHAUST VENT  
MAXIMUM  
AIRINTAKE  
MATERIAL  
AIR INLET  
SIZE (INCHES)  
MAXIMUM  
AIRINTAKE  
MODEL CATEGORY EXHAUST VENT SIZE (INCHES) EXHAUST VENT  
MATERIAL  
LENGTH(FEET)  
LENGTH(FEET)  
GAL. STEEL  
PVC, ABS OR  
CPVC  
TYPE B OR  
10"  
35'  
8"  
35'  
I
I
I
I000  
EQUIVALENT  
(25.4 cm)  
(10.7 m)  
(20.3 cm)  
(10.7 m)  
GAL.STEEL  
PVC, ABS CR  
CPVC  
TYPE B OR  
1300  
1500  
12"  
(30.5 cm)  
35'  
(10.7 m)  
10"  
(25.4 cm)  
35'  
(10.7 m)  
EQUIVALENT  
GAL. STEEL  
PVC, ABS OR  
CPVC  
TYPE B OR  
14"  
(35.6 cm)  
20'  
(6.1 m)  
10"  
(25.4 cm)  
20'  
(6.1 m)  
1850  
2100  
2500  
EQUIVALENT  
GAL. STEEL  
PVC, ABS OR  
CPVC  
TYPE B OR  
14"  
(35.6 cm)  
20'  
(6.1 m)  
12"  
(30.5 cm)  
20'  
(6.1 m)  
I
I
EQUIVALENT  
GAL. STEEL  
PVC, ABS OR  
CPVC  
TYPE B OR  
16"  
(40.6 cm)  
20'  
(6.1 m)  
12"  
(30.5 cm)  
20'  
(6.1 m)  
EQUIVALENT  
• Connection for the appliance exhaust vent to the stack must be as direct as possible. Maximum and minimum venting length  
for Category I appliances shall be determined per the latest edition of the National Fuel Code (U.S.) and CAN/CSA-B149.1  
and .2 Installation Code (Canada).  
• The vent should be installed so as to prevent the accumulation of condensate and, where necessary, have means provided for  
drainage of condensate. The horizontal breaching of a vent must have an upward slope of not less than 1/4 inch per linear foot  
(2 cm/m) from the boiler to the vent terminal. The horizontal portion of the vent shall be supported to maintain clearances and to  
prevent physical damage or separation of joints.  
12  
DIRECT VENT - HORIZONTAL (CATEGORY III)  
Figure 8.  
TABLE 10. DIRECT VENT (HORIZONTAL EXHAUST CONFIGURATIONS)  
APPLIANCE  
MODEL CATEGORY EXHAUST VENT  
MATERIAL  
CERTIFIED  
VENT  
SIZE  
(INCHES)  
MAXIMUM  
VENTLENGTH  
(FEET)  
AIRINTAKE  
MATERIAL  
AIR INLET  
SIZE  
(INCHES)  
MAXIMUM  
AIRINTAKE  
LENGTH(FEET)  
GAL. STEEL  
PVC, ABS OR  
CPVC  
10"  
35'  
8"  
35'  
STAINLESS  
III  
III  
III  
I000  
(25.4 cm)  
(SEALED)  
(10.7 m)  
(20.3 cm)  
(10.7 m)  
GAL.STEEL  
PVC, ABS CR  
CPVC  
1300  
1500  
STAINLESS  
(SEALED)  
12"  
(30.5 cm)  
35'  
(10.7 m)  
10"  
(25.4 cm)  
35'  
(10.7 m)  
GAL. STEEL  
PVC, ABS OR  
CPVC  
STAINLESS  
(SEALED)  
14"  
(35.6 cm)  
20'  
(6.1 m)  
10"  
(25.4 cm)  
20'  
(6.1 m)  
1850  
2100  
2500  
GAL. STEEL  
PVC, ABS OR  
CPVC  
14"  
(35.6 cm)  
20'  
(6.1 m)  
12"  
(30.5 cm)  
20'  
(6.1 m)  
STAINLESS  
(SEALED)  
III  
III  
GAL. STEEL  
PVC, ABS OR  
CPVC  
16"  
(40.6 cm)  
20'  
(6.1 m)  
12"  
(30.5 cm)  
20'  
(6.1 m)  
STAINLESS  
(SEALED)  
WARNING: No substitutions of flue pipe or vent cap material are allowed. Such substitutions would jeopardize the  
safety and health of inhabitants.  
• A maximum of two elbows can be used on inlet and outlet vent piping respectively. Each elbow is equal to 10 feet (3 m) of  
straight pipe.  
• Use only special gas vent pipes listed for use with Category III gas burning heaters, such as stainless steel Saf-T-Vent by Heat  
Fab, Inc. Inc., available from A.O. Smith WPC, 5621 W. 115th Street, Alsip, IL 60803 Phone: 1-800-433-2545 or  
Fax: 1-800-433-2515. Pipe joints must be positively sealed.  
13  
STANDARD (VERTICAL) VENTING, CATEGORYI  
STANDARD (HORIZONTAL) VENTING, CATEGORY III  
Vent sizing, installation and termination shall be in accordance  
with the NATIONAL FUEL GAS CODE, ANSI Z223.1 OR  
CAN/CSA-B149.1 AND .2 (LATEST EDITIONS). If applicable, all  
local, utility, state/provincial regulations on venting must be followed.  
See table 8 for venting specifications. The exhaust vent pipe must  
be of a type listed for use with Category III gas burning heaters  
such as "Saf-T-Vent" manufactured by Heat-Fab Inc.  
THIS BOILER MAY BE VENTED ACCORDING TO TABLE 7 (ALSO  
SEE FIGURE 5). AT LEAST TYPE B VENTING MUST BE USED  
WITH THE STANDARD VENTING OPTION (thru-the-roof) USING  
THE NATIONAL FUEL GAS CODE VENT TABLES.* TYPE B VENT  
PIPE CANNOT BE USED IF THE BOILER IS VENTED  
HORIZONTALLY OR AS A DIRECT VENT (SEE PAGES 11  
THROUGH 13). ALL LOCAL UTILITY, STATE/ PROVINCIAL,  
REGULATIONS ON VENTING MUST BE FOLLOWED.  
For Category III installations, It is important that the Installed vent  
be airtight. Please insure that all joints are sealed properly during  
installation.  
VENT SIZING, INSTALLATION AND TERMINATION SHALL BE IN  
ACCORDANCE WITH THE NATIONAL FUEL GAS CODE, ANSI  
Z223.1 OR CAN/CSA-B149.1 and .2 (AND LATEST ADDENDA).*  
DIRECT VENT VERTICALAND HORIZONTAL VENTING  
For direct vent applications this boiler may be vented according to  
tables 9 and 10. For category III applications, the exhaust vent pipe  
must be special gas vent pipe listed for use with category III gas  
burning heaters such as "Saf-T-Vent" manufactured by Heat-Fab  
Inc. This vent system must be 100% sealed with a condensate  
trap located as close to the boiler as possible.  
Vent connections must be made to an adequate stack or chimney  
and shall be in accordance with the National Fuel Gas Code, ANSI  
Z223.1 or CAN/CSA-B149.1and .2 (and latest addenda) or  
applicable provisions of the local building codes. Size and install  
proper size vent pipe.  
Horizontal runs of vent pipe shall be securely supported by  
adequately placed (approximately every 4 feet [1.2 m]),  
noncombustible hangers suitable for the weight and design of the  
materials employed to prevent sagging and to maintain a minimum  
upward slope of 1/4" per foot (2 cm/m) from the boiler to the vent  
terminals. Dampers or other obstructions must not be installed in  
the vent. Be sure that the vent connector does not extend beyond  
the inside wall of the chimney.  
When sizing exhaust piping and intake air piping, 90-degree elbows  
are equivalent to 10 feet (3.1 m) of straight pipe and 45-degree  
elbows are equal to 5 feet (1.5 m) of straight pipe.  
The intake air piping can be PVC, CPVC, ABS or any suitable intake  
air piping that can be sealed.  
Combustion air from outside the building ducted to boiler air inlet  
(Ducted Air Application) cannot be used in rooms with negative  
pressure.  
Table 11: VENT CONNECTION  
HORIZONTALVENT INSTALLATION  
VENT CONNECTOR  
G(W,B) 1000  
MODEL NUMBER  
10" (25.4 cm)  
This boiler can be vented through the rear of the cabinet with the  
use of the Fluebox and vent adaptor. Any of the previous venting  
configurations can be installed with rear connections.  
G(W,B) 1300  
G(W,B) 1500  
G(W,B) 1850  
G(W,B) 2100  
G(W,B) 2500  
12" (30.5 cm)  
12" (30.5 cm)  
14" (35.6 cm)  
14" (35.6 cm)  
16" (40.6 cm)  
To change the unit to rear exhaust:  
1. The vent collar and cover plates must be removed from the top  
and rear of the unit.  
2. Trim the insulation from around the rear flue hole in the jacket  
and the fluebox. Support insulation from inside the fluebox to  
facilitate cutting. Use safety precautions such as gloves. Place  
the gasket and vent adaptor in the horizontal position. Place the  
gasket and flue plate in the vertical position as shown in  
figure 9.  
For vent arrangements other than table 7 and for proper boiler  
operation, a barometric damper is required to maintain draft  
between -0.02" W.C.. and -0.04" W.C. at 2 feet (0.6 m) above the  
boiler vent collar.  
Figure 9. Switching from Vertical to Horizontal Venting  
14  
CONVENTIONAL SPACE HEATING INSTALLATION  
SYSTEM INSTALLATION  
Modern fin type boilers are exceptionally fast heating units. The low  
water volumes in relation to firing rates require special attention to  
water flow rates for smooth, efficient operation. These  
considerations for the A. O. Smith copper heat exchanger boilers  
are covered below.  
GENERAL  
If the system is to be filled with water for testing or other purposes  
during cold weather and before actual operation, care must be  
taken to prevent a down draft entering the boiler or freezing air from  
contacting the system. Failure to do so may cause the water in the  
system to freeze with resulting damage to the system. Damage Refer to table 4 showing flow rate vs. pressure drop and temperature  
due to freezing is not covered by the warranty.  
rise.  
Good practice requires that all piping, etc., be properly supported.  
Figure 10 shows a typical installation of the boiler.  
The boilers described in this manual may be used for space  
(hydronic) heating or for the heating of potable water. If the heater  
is to be used for hydronic space heating, follow the instructions on  
pages 15-17 given for equipment required for installation as in  
Figure 10. However, if units are to be used for heating potable  
water, the information describing specific systems is found on  
pages 17-19. See figures 11 and 13. Installations must comply  
with all local codes.  
A system with several flow controlled zones, or with a 3-way mixing  
valve system could present a flow rate to the boiler of less than  
required for a maximum of 50°F (28°C) temperature rise. Design  
system with compensating bypasses to the boiler.  
A system bypass should be installed as shown in figure 10 to  
prevent boiler circulation starvation when the system zones call for  
reduced flow.  
This bypass may also be used with multiple boilers manifolded for  
reverse-return flow. The system bypass would be installed from  
boiler outlet to suction side of pump.  
HYDRONIC INSTALLATION  
The following is a brief description of the equipment required for  
installations noted in this manual. All installations must comply  
with local codes (see figure 10).  
The boiler piping system of a hot water heating boiler connected to  
heating coils located in air handling units where they may be  
exposed to circulating refrigerated air, must be equipped with flow  
control valves or other automatic means to prevent gravity circulation  
of the boiler water during the cooling cycle. It is highly recommended  
that the piping be insulated.  
Table 12: INSTALLATION ITEMS  
NO. SUGGESTED ITEMS FOR INSTALLATION  
1. PAIR OF SHORT PIPE NIPPLES, PAIR OF BOILER  
LOOP TEESAND BALL VALVE BETWEEN SYSTEM  
SUPPLY AND RETURN - ONE SET PER EACH BOILER  
2. BOILER PIPE LOOP (See Sizing Data Table 4.)  
3. BOILER CIRCULATING PUMP (See Sizing Data Table 4.)  
4. THERMOMETER  
INSTALLATIONAS BOILER REPLACEMENT  
Installation as boiler replacement on an old system with large water  
volume may result in condensation within the boiler on cold starts.  
This condensing of water vapor in the combustion area can be  
prevented if a portion of the system water flow is diverted past the  
boiler to cause an increase in boiler temperature rise.  
5. PRESSURE GAUGE  
6. LOW WATER CUTOFF (If Required By Local Code.)  
7. SAFETY FLOW SWITCH (Factory-Installed)  
8. RELIEF VALVE (Factory-Installed)  
BYPASS BALANCING  
9. BOILER INLET - OUTLET  
10. SYSTEM SUPPLY TEMPERATURE THERMOMETER  
With systems where water temperature can be expected to drop  
appreciably due to long standby periods, or heavy draw down, a  
bypass pipe of at least 1" size with a balancing cock should be  
installed between the boiler inlet and outlet (see figure 10). When  
the system first starts, the valve should be slowly opened until the  
condensing ceases. This adjustment remains at a permanent  
setting to establish required temperature rise across the boiler.  
11. DRAIN or BLOW-DOWN VALVE  
WATER SUPPLY LINE  
These boilers can be used ONLY in a forced circulation hot water  
heating system. The pump must be interlocked with the boiler to  
prevent boiler operation without water circulation. See maximum  
and minimum flow rate information. Since most forced circulation  
systems will be of the closed type, install the water supply line as  
shown on piping diagram, figure 10. Severe damage will occur if  
the boiler is operated without proper water flow circulation.  
AIR SEPARATOR  
An air separator as shown in the piping diagram is reccommended  
especially for modern commercial hydronic systems.  
VENT VALVES  
Fast filling of large pipe, old radiator installations (where high  
pressures are not available) requires bypassing of the pressure  
reducing valve. Generally, pressure purging is not possible with a  
well pump system. High point air venting is essential. For details,  
refer to OPERATION section of this manual on page 22.  
It is recommended that automatic, loose key or screwdriver type  
vent valves be installed at each convector or radiator.  
SYSTEM HEADERS  
If the system is of the open type, a pressure reducing valve will not  
be required as the water supply to the system will be controlled by  
a manually operated valve. An overhead surge tank is required. A  
MINIMUM PRESSURE OF 15 PSI (100 kPa) MUST BE MAINTAINED  
ON THE BOILER AT ALL TIMES to avoid potential damage to the  
boiler that may not be covered by the warranty.  
Split systems with individual supply and return lines from the boiler  
room should normally have this piping connected to supply and  
return manifold headers near the boiler. To achieve good water  
distribution with minimum pressure drop for several circuits,  
manifolds should be larger than system loops.  
15  
The circuits should be spaced on the header at a minimum of  
3" (7.6 cm) center to center. Install a balancing cock in each return  
line.  
installation might be controlled directly from space temperature  
thermostat(s). Multiple boiler installations are more effective when  
the boilers are sequenced in and out of operation by some form of  
main water temperature controller. With one or two boilers, individual  
control settings at progressive temperature may be used. For more  
than two boilers, electronic sequencing controlling is  
recommended.  
Manifold headers are recommended for split systems with or  
without zone valves and also those installations with zone  
circulators. If the system is to be split at remote points, good practice  
requires special attention be given to main pipe sizing to allow  
balancing of water flow.  
Individual controls, or the separate stages of a step controller,  
should fire a boiler and also start the boiler loop circulator whenever  
that boiler is fired. Some large installations may require the firing  
of more than one boiler per stage.  
COOLING PIPING  
When the boiler is used in conjunction with a refrigeration system  
it must be installed so that the chilled medium is piped in parallel  
with the boiler. Appropriate valves, manual or motorized, must be  
provided to prevent the chilled medium from entering the boiler.  
The system or primary circulator may or may not be controlled by  
the boiler sequencer. When this pump is operated through the first  
switch of any type of step controller, care should be taken to  
determine if a motor starter is needed due to insufficient switch  
capacity.  
Water temperature in the heating system must be reduced to less  
than 100°F before cooling system is started, or damage to the  
chiller unit may occur.  
If the primary pump is controlled by a manual switch or any other  
controllers, the electric current supply to the boiler group should be  
through the primary pump controller. The fast response of  
A.O. Smith boilers eliminates any need to maintain boiler  
temperature when the system is satisfied. Wiring should always  
prevent firing of boiler(s) when there is no water flow in the  
mains.  
If the boiler is connected to chilled water piping or heating coils  
exposed to refrigerated air, the boiler piping system must be  
equipped with flow control valves or other automatic means to  
prevent gravity circulation through the boiler during the cooling cycle.  
Primary/secondary pumping of both the chiller(s) and the boiler(s)  
is an excellent winter-summer change-over method, because  
cooling flow rates are much more than heating flow rates. In this  
way each system (heating or cooling) is circulated independently.  
Installation diagrams show safety flow switches in the outlet piping  
from each boiler as good protection against any boiler being fired  
when the boiler loop circulator is not in operation. These safety flow  
switches will also provide some protection if there is a loss of water.  
SPACE HEATING APPLICATIONS  
Controlling of these systems is decided mainly by the type of  
building system controlling that is desired. A single boiler  
Multiple boiler installations are especially adapted to the use of  
outdoor reset for main water temperatures. This feature is not  
Figure 10. Single or Multiple Boiler Installation Diagram  
16  
mandatory but offers smooth, efficient operation of a modern  
system.  
HARD WATER CONDITIONS  
Where hard water conditions exist, water softening or the threshold  
type of water treatment is recommended. This will protect the  
dishwashers, coffee urns, water heaters, water piping and other  
equipment. When water softening or water treatment is not practical,  
a comparatively easy method of periodic lime removal from the unit  
must be employed.  
Normal use of flow control valves is required to prevent cross  
circulation of zones as with any multiple pump system.  
Large systems with multiple boilers should include main water  
temperature controls (with or without outdoor reset) to sequence  
the boiler on and off, in relation to the load on the system.  
WARNING  
24 VAC System Controller (Optional)  
LIME ACCUMULATION CAN REDUCE THE LIFE OF THE  
EQUIPMENT, REDUCE EFFICIENCYAND WASTE FUEL. BOILER  
FAILURE DUE TO LIME OR SCALE BUILDUP VOIDS THE  
WARRANTY.  
GB models require a field supplied 24VAC operating control to be  
installed in the system such as: loop thermostat, indoor/outdoor  
reset control, sequencing panel, or energy management system.  
The connection for such devices is located in the 24 VAC junction  
box at the rear of the unit. A 24 VAC thermostat/aquastat can only be  
used as an "On/Off" switch for the unit. The actual controlling of the  
staging will be through either the inlet or tank probe. To use a 24 VAC  
system controller, dip switch "E" on the CCB must be switched to the  
"on" position. See figure 14.  
Tank Probe (Optional)  
In addition to the Inlet and Outlet/ECO Probes, units can be  
optionally equipped with a tank Probe. The connection for the tank  
probe is located in the 24VAC junction box at the rear of the unit.  
The tank Probe can be configured to control the staging of the unit.  
See Tank Probe Installation section below for additional  
information.  
INTERNALCONTAMINANTS  
The system must be internally cleaned and flushed after a new or  
replacement unit has been installed to remove contaminants that  
may have accumulated during installation. This is doubly important  
when a replacement unit is installed into an existing system where  
Stop Leak or other boiler additives have been used.  
TANK PROBE INSTALLATION PROCEDURE  
A tank probe is supplied with each hot water supply boiler (GW). To  
connect the tank probe to the boiler, remove the cover from the 24  
VAC junction box at the rear of the unit. Connect the probe wires  
across terminals 1 & 2. (The wires leading to the terminals will be  
yellow.) Check the field connection diagram located on this cover  
of the junction box to assure proper wiring.  
All systems should be completely flushed with a grease removing  
solution to assure trouble-free operation. Pipe joint compounds,  
soldering paste, grease on tubing and pipe all tend to contaminate  
a system.  
Once the tank probe has been connected to the boiler, it must be  
designated as the controlling probe for the system. This is  
accomplished by changing two Dip Switch settings on the Central  
Control Board. First, Dip Switch "D" must be set to the "ON" position  
to designate the tank probe as the controlling probe. Second, Dip  
Switch "G" must be set to the "OFF" position to limit the maximum  
tank probe temperature for GW applications. It is also advisable to  
make sure Dip Switch "F" is set to the "OFF" position which sets the  
Outlet temperature Set-Point to 210°F (99°C). See figure 14. Failure  
to do this will void the warranty. If the tank probe is not designated  
as the controlling probe, the staging of the unit will be controlled by  
the Inlet Probe and will not use the desired tank temperature as its  
base. Once the tank Probe is designated as the controlling probe,  
the Inlet Water Temperature on the display will default to the tank  
temperature.  
Failure to clean and flush the system can cause solids to form on  
the inside of the heat exchanger, can produce acid concentrations  
that become corrosive, can allow excessive amounts of air or other  
gases to form which could block circulation, foul system  
accessories and damage circulator seals and impellers.  
It is recommended that after installation, the boiler and system  
when filled should include the proper percentage of cleaning  
solution related to approximate water volume of the system. Fire  
and circulate for about one hour and then flush clean with fresh  
water. Commercial grease removing solutions are available.  
Before operating the boiler, the entire system must be filled with  
water, purged of air and checked for leaks. Do not use Stop Leak or  
other boiler compounds. The gas piping must also be leak tested.  
THE WATER HEATER SHOULD BE LOCATED INANAREAWHERE  
THE GENERAL PUBLIC DOES NOT HAVE ACCESS TO SET  
TEMPERATURES.  
Refer to "Connection Diagram" (figure 20) and figure 12 in order to  
connect the tank probe to the boiler.  
See section titled "PROCEDURES FOR SETTING TANK PROBE  
TEMPERATURE", following the Lighting Instructions for instructions  
on how to set the temperature.  
HOT WATER SUPPLY BOILER  
INSTALLATION  
EXPANSION TANK  
WATER LINE CONNECTIONS  
If the system is of the closed type, install an expansion tank as  
shown in figures 11 and 13. The sizing of the expansion tank for a  
Where excessive heat exchanger condensation exists due to closed system is very important and is directly related to the total  
continued low inlet water temperatures (below 120oF), a bypass  
balance loop must be installed (see figures 11 and 13).  
water volume of the system. Refer to ASME or other reliable  
specifications for sizing.  
17  
ONE GENESIS (MODEL GW) HOT WATER SUPPLY BOILER WITH HORIZONTAL TANK  
PRESSURE RELIEF VALVE RATING SHOULD  
NOT EXCEED PRESSURE CAPACITY OF ANY  
COMPONENT IN THE SYSTEM.  
IMPORTANT  
SAFETY FLOW SWITCH PROTECTS THE  
BOILER IN CASE OF WATER SERVICE  
INTERRUPTION OR CIRCULATOR FAILURE.  
NSTALL THERMAL EXPANSION  
TANK ON COLD WATER  
SUPPLY LINE, IF CHECK VALVE  
OR PRESSURE REDUCING  
VALVE IS USED IN SUPPLY.  
PIPING SHOULD CONFORM TO LOCAL CODES.  
X
PIPE TO OPEN DRAIN  
FACTORY-INSTALLED ON UNIT  
BALL VALVES ARE SHOWN FOR SERVICING  
BOILER. HOWEVER, LOCAL CODES SHALL  
GOVERN THEIR USAGE.  
 SUPPLIED WITH UNIT  
FIELD-INSTALLED  
DANGER  
TEMPERATURE SETTING SHOULD NOT EXCEED  
SAFE USE TEMPERATURE AT FIXTURES
SEE WATER TEMPERATURE CONTROL  
WARNING ON PAGE 23. IF HIGHER PREHEAT  
TEMPERATURESARE NECESSARYTO OBTAIN  
ADEQUATE BOOSTER OUTPUT, ADD AN  
ANTI-SCALD VALVE FOR HOT WATER  
SUPPLIED TO FIXTURES.  
WARNING  
THE WATER MANIFOLD IS NOT DESIGNED TO  
SUPPORT THE WEIGHT OF THE WATER PIPING  
SYSTEM. AS ONALL BOILER INSTALLATIONS
SPECIAL CARE MUST BE TAKEN TO ENSURE  
PROPER SUPPORT.  
TWO TEMPERATURE WATER  
MIXING VALVE APPLICATION  
MINIMUM  
MODELS  
MODELS  
PIPE SIZE  
INCHES  
CIRCULATING RETURN  
LINE CONNECTIONS  
GW-1000  
THRU  
2 1/2"  
NPT  
• TEMPERED WATER LOOP, IF USED,  
CONNECT TO POINT R.  
2500  
• STOREDTEMPERATURE WATER LOOP,  
IF USED, CONNECT TO ANY OPENING  
NEAR BOTTOM OFTANK.  
FACTORY PUMP SIZING  
BASED ON 50 EQUIVALENT  
FEET (15.2 m) OF PIPE.  
Figure 11. Single boiler with horizontal tank.  
Encase field-supplied wires  
between tank probe and junction  
box with 1/2" field supplied  
conduit. "Pigtails" of field-  
supplied wires should be spliced  
to "pigtails" of tank probe and  
connected to 24 VAC junction box  
(see figure 20). This conduit and  
wiring should be separate from  
any other conduit/wiring to guard  
against EMI (electromagnetic  
interference).  
Figure 12. Tank probe installation.  
18  
ONE GENESIS (MODEL GW) HOT WATER SUPPLY BOILER WITH VERTICAL TANK  
PRESSURE RELIEF VALVE RATING SHOULD NOT EXCEED PRESSURE CAPACITY OF ANY COMPONENT IN THE SYSTEM.  
PIPING SHOULD CONFORM TO LOCAL CODES.  
BALL VALVES ARE SHOWN FOR SERVICING BOILER. HOWEVER, LOCAL CODES SHALL GOVERN THEIR USAGE.  
IMPORTANT  
SAFETY FLOW SWITCH PROTECTS THE BOILER IN CASE OF WATER SERVICE INTERRUPTION OR CIRCULATOR FAILURE.  
X
PIPE TO OPEN DRAIN  
FACTORY INSTALLED ON UNIT  
 SUPPLIED WITH UNIT  
FIELD-INSTALLED  
DANGER  
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE  
TEMPERATUREAT FIXTURES. SEE WATER TEMPERATURE  
CONTROL WARNING ON PAGE 23. IF HIGHER PREHEAT TEM-  
PERATURES ARE NECESSARY TO OBTAIN ADEQUATE  
BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT  
WATER SUPPLIED TO FIXTURES.  
TWO TEMPERATURE WATER  
MIXING VALVE APPLICATION  
MINIMUM  
PIPE SIZE  
INCHES  
MODELS  
MODELS  
GW-1000  
THRU  
2 1/2"  
NPT  
2500  
FACTORY PUMP SIZING BASED  
ON 50 EQUIVALENT FEET  
(15.2 m) OF PIPE.  
INSTALL THERMAL EXPANSION  
TANK ON COLD WATER SUPPLY  
LINE, IF CHECK VALVE OR  
PRESSURE REDUCING VALVE  
IS USED IN SUPPLY.  
CIRCULATING RETURN  
LINE CONNECTIONS  
• TEMPERED WATER LOOP, IF USED,  
CONNECT TO POINT R.  
• STOREDTEMPERATURE WATER LOOP,  
IF USED, CONNECT TO ANY OPENING  
NEAR BOTTOM OFTANK.  
Figure 13. Single boiler with vertical tank.  
19  
20  
threads of pipe joints. Do not apply compound to the first two  
threads. Use compounds resistant to the action of liquefied  
petroleum gases.  
GAS CONNECTIONS  
WARNING  
THIS BOILER IS NOT INTENDED TO OPERATE AT GAS SUPPLY  
PRESSURE OTHER THAN SHOWN ON THE RATING PLATE.  
EXPOSURE TO HIGHER GAS SUPPLY PRESSURE MAY CAUSE  
DAMAGE TO GAS VALVES WHICH CAN RESULT IN FIRE OR  
EXPLOSION. IF OVERPRESSURE HAS OCCURRED SUCH AS  
THROUGH IMPROPER TESTING OF GAS LINES OR EMERGENCY  
MALFUNCTION OFTHE SUPPLY SYSTEM, THE GAS VALVES MUST  
BE CHECKED FOR SAFE OPERATION. MAKE SURE THAT THE  
OUTSIDE VENTS ON THE SUPPLY REGULATORS AND THE  
SAFETY VENT VALVESARE PROTECTEDAGAINST BLOCKAGE.  
THESE ARE PARTS OF THE GAS SUPPLY SYSTEM, NOT THE  
BOILER. VENT BLOCKAGE MAY OCCUR DURING ICE BUILD-UP  
OR SNOW STORMS.  
THE BOILER MUST BE ISOLATED FROM THE GAS SUPPLY PIPING  
SYSTEM BY CLOSING ITS MAIN MANUALGAS SHUT-OFF VALVE  
DURINGANY PRESSURE TESTING OF THE GAS SUPPLY PIPING  
SYSTEM AT TEST PRESSURES EQUAL TO OR MORE THAN 1/2  
PSIG.  
1. CORRECT GAS - Make sure gas on which the boiler will operate  
is the same as that specified on the rating plate. Do not install  
the boiler if equipped with a different type of gas. Consult your  
gas supplier.  
2A. SIZING GAS SUPPLY LINE (For single boiler installations).  
See table 15.  
WHEN LOCAL CODES REQUIRE A MAIN MANUAL SHUT-OFF  
VALVE OUTSIDE THE BOILER JACKET,ASUITABLE MAIN MANUAL  
SHUT-OFF VALVE MUST BE INSTALLED IN A LOCATION  
COMPLYING WITH THOSE CODES.  
2B. SIZING GAS SUPPLY LINE (For multiple installations of  
two or more boilers). See tables 13 (Natural Gas) and 14  
(Propane Gas).  
TABLE 15. SINGLE UNIT INSTALLATION, SUGGESTED  
PIPE SIZE  
ITIS IMPORTANTTO GUARDAGAINSTGAS VALVE FOULING FROM  
CONTAMINANTS IN THE GAS WAYS. SUCH FOULING MAY CAUSE  
IMPROPER OPERATION, FIRE OR EXPLOSION. IF COPPER  
SUPPLY LINESARE USED THEY MUST BEAPPROVED FOR GAS  
SERVICE.  
DISTANCE FROM METER  
BTU INPUT 0-50' 51-100' 101-200' 201-300' 301-500'  
990,000  
1,300,000  
1,500,000  
2"  
2"  
2"  
2"  
2 1/2"  
2 1/2"  
3"  
2 1/2"  
3"  
2 1/2"  
3"  
2 1/2"  
2 1/2"  
BEFORE ATTACHING THE GAS LINE BE SURE THAT ALL GAS  
PIPE IS CLEAN ON THE INSIDE.  
3"  
3 1/2"  
3 1/2"  
4"  
1,850,000 2 1/2" 2 1/2"  
3"  
3"  
TO TRAPANY DIRT OR FOREIGN MATERIALIN THE GAS SUPPLY  
LINE, A DIRT LEG (SOMETIMES CALLED DRIP LEG) MUST BE  
INCORPORATED IN THE PIPING. THE DIRT LEG MUST BE  
READILY ACCESSIBLE AND NOT SUBJECT TO FREEZING  
CONDITIONS. INSTALL IN ACCORDANCE WITH RECOM-  
MENDATIONS OF SERVING GAS SUPPLIERS. REFER TO  
NATIONAL FUEL GAS CODE, ANSI Z223.1 OR CAN/CSA -B149.1  
AND .2 (AND LATESTADDENDA).  
2,100,000 2 1/2"  
2,500,000 2 1/2"  
3"  
3"  
3"  
3 1/2"  
4"  
4"  
4 1/2"  
Use tables 13 or 14, which are taken from ANSI booklet Z223.1,  
NATIONAL FUELGAS CODE, or CAN/CSA-B149.1and .2 (and latest  
addenda) to size iron pipe or equivalent gas supply line. Table 13  
is based on a pressure drop of 0.5 inches of water and a specific  
gravity of 0.60 approximately that of natural gas. (LP gas has an  
S.G. of about 1.53). If the service pressure is five inches water  
column or less, use one pipe size larger than specified in tables  
13-15 in order to minimize pressure drop in the line.  
Gas Pipe sizing may be larger than heater connections on  
installations where a significant run of piping is required. To prevent  
damage, care must be taken not to apply too much torque when  
attaching gas supply pipe to gas inlet.  
No additional allowance is necessary for an ordinary number of  
fittings. Where it is necessary to use more than the average number  
of pipe fittings i.e. elbows, tees, and valves in gas supply line, use  
a pipe larger than specified to compensate for increased pressure  
drop.  
Fittings and unions in the gas line must be metal to metal type.  
Apply joint compounds (pipe dope) sparingly and only to the male  
TABLE 16. Orifice Size for Natural and Propane (LP) Gases (U.S. and Canadian Installations)  
[Drill size unless otherwise indicated.]  
Rating Input  
BTUH  
990,000  
1,300,000  
1,500,000  
1,850,000  
2,100,000  
2,490,000  
Number of  
Burners  
10  
Model  
Natural (Holes)  
0.111" (4X)  
0.111" (4X)  
0.111" (4X)  
0.111" (4X)  
0.111" (4X)  
0.111" (4X)  
Propane (Holes)  
0.071" (3X)  
0.071" (3X)  
0.071" (3X)  
0.071" (3X)  
0.071" (3X)  
0.071" (3X)  
GB/GW 1000  
GB/GW 1300  
GB/GW 1500  
GB/GW 1850  
GB/GW 2100  
GB/GW 2500  
13  
15  
19  
21  
25  
21  
WIRING CONNECTIONS  
OPERATION  
ALLELECTRICAL WORK MUST BE INSTALLED INACCORDANCE  
WITH THE MOST RECENT VERSION OF THE NATIONAL  
ELECTRICAL CODE/CANADIAN ELECTRICAL CODE AND MUST  
CONFORM TO LOCALREGULATIONS.  
IMPORTANT  
Only qualified personnel shall perform the initial firing of the heater.  
At this time the user should not hesitate to ask the start-up  
technician any questions regarding the operation and maintenance  
of the unit. If you still have questions, please contact the factory or  
your local A.O. Smith representative.  
AN ELECTRICAL GROUND IS REQUIRED TO REDUCE RISK OF  
ELECTRIC SHOCK OR POSSIBLE ELECTROCUTION. Make the  
ground connection to the wire provided in the electrical supply  
junction box on the boiler.  
Lighting and Operating instructions are included with this manual.  
By using these instructions, the user may be able to make minor  
operational adjustments and save unnecessary service calls.  
However the user should not attempt repairs, but should contact a  
service technician or gas supplier.  
Grounding and all wiring connected to this boiler must conform to  
the local code authority having jurisdiction or, in the absence of  
such requirements, with the National Electrical Code, ANSI/NFPA  
70 or CSA-C22.2 most recent edition.  
GENERAL  
The Central Control Board and Ignition Control Boards that make  
up the control system are micro-processor based which make  
them vulnerable to voltage and amperage fluctuations in the power  
supply. It is imperative that they be protected by a suitable  
commercial-grade surge protection device.  
Never operate the boiler without first making sure the boiler and  
system are filled with water, in addition:  
For hot water supply installations:  
• Make sure a temperature and pressure relief valve is installed at  
the boiler and, if used, the storage tank. Also check for leaks.  
IF ANY OF THE ORIGINAL WIRE, AS SUPPLIED WITH THE  
APPLIANCE, MUST BE REPLACED, IT MUST BE REPLACED WITH  
TYPE 105°C WIRE OR ITS EQUIVALENT.  
For heating boiler installations:  
• Make sure that the boiler and system have been purged of air  
and checked for leaks.  
The Genesis Hot Water Supply Boiler must be connected to a single  
phase line source that is:  
Also be sure to check the gas piping for leaks before beginning the  
initial firing of the boiler.  
120 volts, 60 Hertz, and 30 Amps.  
The system controller, other than the factory-supplied tank probe  
(e. g. Honeywell Aquastat) must be wired on the low voltage side of  
the 24VAC rear junction box.  
FILLINGAND PURGING FOR HEATING  
BOILER INSTALLATION  
1. Fast fill system through bypass until pressure approaches  
desired system pressure. Close bypass valve and permit  
pressure to be established by the pressure reducing valve.  
Refer to the Schematic Diagram (Figure 19) and the Connection  
Diagram (Figure 20) for wire connections.  
Fuse Protection  
2. Vent all high points in system to purge system of air.  
The 24 VAC circuitry is protected with a 3 amp auto fuse on the  
ignition control boards and a 5 amp fuse on the Central Control  
Board. If the fuse opens, a red LED located near the fuse will light  
(see figures 14 and 15). If the red LED is illuminated, replace the  
fuse. Repeated failure of the fuse is an indication of possible  
damage to the ignition control. The 120V circuits of each ignition  
control module is protected with a 10 amp fuse located inside the  
control box.  
Provisions should be made to permit manual venting of radiators  
or convectors.  
FILLING FOR HOT WATER SUPPLYBOILER INSTALLATION  
1. Close the systems drain valve by turning handle clockwise.  
2. Open a nearby hot water faucet to permit the air in the system to  
escape.  
Note: Four extra 3 amp fuses and one 5 amp fuse are supplied  
with the boiler.  
3. Fully open the cold water inlet pipe valve allowing the heater  
and piping to be filled.  
Recommended Replacement fuses:  
4. Close the hot water faucet as water starts to flow.  
5. The heater is ready to be operated.  
3 Amp: Littlefuse automotive fuse PN 257003  
5 Amp: Bussman Automotive fuse PN ATC5  
22  
2. CHECK THE INPUT. SEE SECTIONS "INLET GAS PRESSURE:"  
AND SEE NATIONALFUEL GAS CODE,ANSI Z223.1 OR CAN/  
CSA - B149.1 AND .2 (AND LATEST ADDENDA) FOR  
PROCEDURES.  
PURGING OF GAS LINE  
Gas line purging is required with new piping or systems in which  
air has entered.  
DANGER  
CAUTION  
HOT WATER TEMPERATURES REQUIRED FOR AUTOMATIC  
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD  
BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/OR  
DEATH. THE TEMPERATUREATWHICH INJURY OCCURS VARIES  
WITH THE PERSON'S AGE AND TIME OF EXPOSURE. THE  
SLOWER RESPONSE TIME OF CHILDREN, AGED OR DISABLED  
PERSONS INCREASES THE HAZARDS TO THEM. NEVER ALLOW  
SMALL CHILDREN TO USE A HOT WATER TAP, OR TO DRAW  
THEIR OWN BATH WATER. NEVER LEAVEACHILD OR DISABLED  
PERSON UNATTENDED IN A BATHTUB OR SHOWER.  
PURGING SHOULD BE PERFORMED BY PERSONS  
EXPERIENCED IN THIS TYPE OF GAS SERVICE TOAVOID RISK  
OF FIRE OR EXPLOSION. PURGE DISCHARGE MUST NOT  
ENTER CONFINED AREAS OR SPACES WHERE IGNITION CAN  
OCCUR. THE AREA MUST BE WELL VENTILATED AND ALL  
SOURCES OF IGNITION MUST BE DEACTIVATED OR REMOVED.  
BEFORE PLACING THE BOILER IN OPERATION, CHECK FOR  
GAS LEAKAGE. USEASOAPAND WATER SOLUTION OR OTHER  
MATERIALACCEPTABLE FOR THE PURPOSE OF LOCATING GAS  
LEAKS. DO NOT USE MATCHES, CANDLES, FLAME OR OTHER  
SOURCES OF IGNITION FOR THIS PURPOSE.  
THE WATER HEATER SHOULD BE LOCATED INANAREAWHERE  
THE GENERAL PUBLIC DOES NOT HAVE ACCESS TO SET  
TEMPERATURES.  
WARNING  
THE GAS VALVE MUST HAVE BEEN INTHE OFF POSITION FORAT  
LEAST 5 MINUTES. This waiting period is an important safety  
step. Its purpose is to permit gas that may have accumulated in  
the combustion chamber to clear. IF YOU DETECT GAS ODOR AT  
THE END OF THIS PERIOD DO NOT PROCEED WITH LIGHTING.  
RECOGNIZE THAT GAS EVEN IF IT SEEMS WEAK, MAY INDICATE  
PRESENCE OFACCUMULATED GAS SOMEPLACE IN THEAREA  
WITH RISK OF FIRE OR EXPLOSION. SEE THE FRONT PAGE  
FOR STEPS TO BE TAKEN.  
INLET GAS PRESSURE  
The inlet gas pressure is measured by removing the low gas  
pressure switch located on the main gas manifold which is  
upstream of the unit's combination gas valves. The maximum  
value specified in the table must not be exceeded. The minimum  
values shown in table 17 must be maintained under both load and  
no load conditions (static and dynamic). The combination gas  
valves supplied with the boiler are for low pressure service. If  
upstream pressure exceeds 14.0" W.C., an intermediate gas  
pressure regulator of the lockup type must be installed.  
It is recommended in domestic hot water applications that lower  
water temperatures be used to avoid the risk of scalding. It is  
further recommended, in all cases, that the water temperature be  
set for the lowest temperature which satisfies the user's hot water  
needs. This will also provide the most energy efficient operation of  
the boiler and minimize scale formation in the heat exchanger,  
thus prolonging the life of the boiler.  
TABLE 17.  
Inlet Gas Pressure  
Max. Inlet Pressure (Inches W.C.)  
Min. Inlet Pressure (Inches W.C.)  
Nat. Gas  
14.0  
Prop. Gas  
14.0  
6.0  
11.0  
SETTING THE WATER HEATER TEMPERATURE AT 120°F (49°C)  
WILL REDUCE THE RISK OF SCALDS. Some states require  
settings at specific lower temperatures. Table 18 below shows the  
approximate time-to-burn relationship for normal adult skin.  
MANIFOLD PRESSURE  
The manifold gas pressure is measured at the pressure tap on  
the downstream side of the combination gas valve(s). For natural  
gas the Manifold Pressure should measure 3.5" W.C. For propane  
(LP) gas, the pressure should read 10" W.C.  
TABLE 18. Risk of Scalds  
Temperature  
Setting  
Time to Produce 2nd & 3rd  
Degree Burns on Adult Skin  
Nearly instantaneous  
About 1/2 second  
IMPORTANT  
Over 170°F (77°C)  
160°F (71°C)  
150°F (66°C)  
140°F (60°C)  
130°F (54°C)  
120°F (49°C) or less  
UNDER NO CIRCUMSTANCES SHALL THE GAS PRESSURE  
MEASUREDATTHE BURNER MANIFOLD EXCEED THAT STATED  
ON THE BOILER RATING PLATE. OVERFIRING WILL RESULT IN  
DAMAGE TO THE BOILER, AS WELL AS INCREASED RISK OF  
FIRE, SOOTINGANDASPHYXIATION.  
About 1-1/2 seconds  
Less than 5 seconds  
About 30 seconds  
More than 5 minutes  
ADJUSTMENTS  
USE ANTI-SCALD VALVE(S) in the hot water system to reduce the  
risks of scalding at points of use such as lavatories, sinks and  
bathing facilities.  
ON INITIALSTARTUP SOMEADJUSTMENTSARE NECESSARY.  
1. CHECK MANIFOLD AND INLET GAS PRESSURES.  
23  
Lighting Instructions for the G(B/W) 1000 through 2500 models  
FOR YOUR SAFETY READ BEFORE OPERATING  
WARNING: IF YOU DO NOT FOLLOW THESE INSTRUCTIONS EXACTLY, AFIRE OR  
EXPLOSION MAY RESULT CAUSING PROPERTY DAMAGE, PERSONAL INJURY OR  
LOSS OF LIFE.  
A. THIS APPLIANCE DOES NOT HAVE A PILOT. IT IS  
C. USE ONLY YOUR HAND TO PUSH IN OR TURN THE GAS  
CONTROL KNOB. NEVER USE TOOLS. IF THE KNOB WILL  
NOT PUSH IN OR TURN BYHAND, DON’T TRYTO REPAIR  
IT. CALLAQUALIFIED SERVICE TECHNICIAN. FORCE OR  
ATTEMPTED REPAIR MAY RESULT IN A FIRE OR  
EXPLOSION.  
EQUIPPED WITH AN IGNITION DEVICE WHICH  
AUTOMATICALLYLIGHTS THE BURNER. DO NOT TRYTO  
LIGHT THE BURNER BY HAND.  
B. BEFORELIGHTING:SMELLALLAROUNDTHEAPPLIANCE  
AREAFORGAS. BESURETOSMELLNEXTTOTHEFLOOR  
BECAUSE SOME GAS IS HEAVIER THANAIR AND WILL  
SETTLE ON THE FLOOR.  
D. DO NOT USE THISAPPLIANCE IFANY PART HAS BEEN  
UNDER WATER. IMMEDIATELY CALL A QUALIFIED  
SERVICE TECHNICIAN TO INSPECT THE APPLIANCE AND  
TO REPLACEANYPART OF THE CONTROL SYSTEMAND  
ANY GAS CONTROLWHICH HAS BEEN UNDER WATER.  
WHAT TO DO IF YOU SMELL GAS  
DO NOT TRY TO LIGHT ANY APPLIANCE.  
DO NOT TOUCH ANY ELECTRIC SWITCH; DO NOT  
USE ANY PHONE IN YOUR BUILDING.  
IMMEDIATELY CALL YOUR GAS SUPPLIER FROM A  
NEIGHBOR’S PHONE. FOLLOW THE GAS SUPPLIER’S  
INSTRUCTIONS.  
IF YOU CANNOT REACH YOUR GAS SUPPLIER, CALL  
THEFIREDEPARTMENT.  
E. DO NOT OPERATEAPPLIANCE UNLESS UNIT IS FILLED  
WITH WATERAND WATER LINESARE FULLYOPEN.  
OPERATING INSTRUCTIONS  
1.  
STOP! READ THE SAFETYINFORMATION THE  
NEXT STEP ABOVE ON THIS LABEL.  
STOP ! FOLLOW “B” IN THE SAFETY INFORMATION  
ABOVE ON THIS LABEL.  
2. SET THE SYSTEM CONTROLLER TO THE LOWEST  
SETTING.  
IF YOU DON’T SMELLGAS, GO TO THE NEXT STEP.  
8. TURN TOP KNOB OF GAS CONTROL COUNTER-  
3. TURN OFF ALL ELECTRIC POWER TO APPLIANCE.  
4. THIS APPLIANCE IS EQUIPPED WITH AN IGNITION  
DEVICE WHICHAUTOMATICALLY LIGHTS THE BURNER.  
DO NOT TRY TO LIGHT THE BURNER BY HAND.  
5. REMOVE CONTROLACCESS PANEL.  
CLOCKWISE  
9. REPLACE CONTROLACCESS PANEL.  
TO “ON” POSITION, (FIG. B).  
10. TURN POWER SWITCH TO “ON” POSITION.  
11. SET THE SYSTEM CONTROLLER TO DESIRED SETTING.  
12. IF THEAPPLIANCE WILL NOT OPERATE, FOLLOW THE  
INSTRUCTIONSTOTURNOFFGASTOTHEAPPLIANCE”  
AND CALL YOUR SERVICE TECHNICIAN OR GAS  
SUPPLIER.  
6. REFERTODIAGRAMSABOVE. TURNTOPKNOBOFGAS  
CONTROL CLOCKWISE  
TO “OFF” POSITION, (FIG. A).  
7. WAIT FIVE (5) MINUTES TO CLEAR OUTANY GAS. THEN  
SMELL FOR GAS, INCLUDING NEAR THE FLOOR. IF YOU  
SMELL GAS,  
TO TURN OFF GAS TO APPLIANCE  
4. REFERTODIAGRAMSABOVE. TURNTOPKNOBOFGAS  
CONTROL CLOCKWISE (TO “OFF” POSITION, (FIG. A).  
5. REPLACE CONTROLACCESS PANEL.  
1. SET THE SYSTEM CONTROLLER TO THE LOWEST  
SETTING.  
2. TURN POWER SWITCH ON APPLIANCE TO “OFF”  
POSITION.  
3. REMOVEACCESS PANELTO EXPOSE GAS CONTROL.  
24  
Lighting Instructions for the G(B/W) 1000 through 2500 models  
FOR YOUR SAFETY READ BEFORE OPERATING  
WARNING: IF YOU DO NOT FOLLOW THESE INSTRUCTIONS EXACTLY, A  
FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY DAMAGE,  
PERSONAL INJURY OR LOSS OF LIFE.  
C. USE ONLYYOUR HAND TO TURN THE MAIN MANUAL GAS  
A. THISAPPLIANCE DOES NOT HAVEAPILOT. IT IS EQUIPPED  
WITH AN IGNITION DEVICE WHICH AUTOMATICALLY  
LIGHTSTHEBURNER. DONOTTRYTOLIGHTTHEBURNER  
BYHAND.  
B. BEFORE LIGHTING: 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.  
VALVE HANDLE. NEVER USE TOOLS. IF THE HANDLE WILL  
NOT TURN BY HAND, DON’T TRY TO REPAIR IT. CALL A  
QUALIFIED SERVICE TECHNICIAN. FORCE ORATTEMPTED  
REPAIR MAYRESULT INAFIRE OR EXPLOSION.  
D. DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN  
UNDERWATER. IMMEDIATELYCALLAQUALIFIED SERVICE  
TECHNICIAN TO INSPECT THE APPLIANCE AND TO  
REPLACEANYPART OF THE CONTROL SYSTEMANDANY  
GAS CONTROL WHICH HAS BEEN UNDER WATER.  
WHAT TO DO IF YOU SMELL GAS  
DO NOT TRY TO LIGHT ANY APPLIANCE.  
DO NOT TOUCH ANY ELECTRIC SWITCH.  
DO NOT USE ANY PHONE IN YOUR BUILDING.  
IMMEDIATELY CALL YOUR GAS SUPPLIER FROM A  
NEIGHBOR’S PHONE. FOLLOW THE GAS SUPPLIER’S  
INSTRUCTIONS.  
E. DO NOT OPERATEAPPLIANCE UNLESS UNIT IS FILLED  
WITH WATERAND WATER LINESARE FULLYOPEN.  
IF YOU CANNOT REACH YOUR GAS SUPPLIER, CALL  
THEFIREDEPARTMENT.  
OPERATING INSTRUCTIONS  
1.  
STOP!READTHESAFETYINFORMATIONABOVEON  
THIS LABEL.  
SET THE SYSTEM CONTROLLER TO THE LOWEST  
SETTING.  
STOP! FOLLOW “B” IN THE SAFETY INFORMATION  
ABOVE ON THIS LABEL. IF YOU DON’T SMELL GAS, GO  
TO THE NEXT STEP.  
2
7. TURN MAIN MANUAL GAS VALVE TO “ON” POSITION,  
(FIGURE “A”), THE VALVE IS “ON” WHEN THE HANDLE IS  
PARALLEL TO THE GAS FLOW DIRECTION.  
3. TURN POWER SWITCH ON APPLIANCE TO “OFF”  
POSITION.  
4. TURN MAIN MANUAL GAS VALVE TO “OFF” POSITION,  
(FIGURE “B”). THE VALVE IS “OFF” WHEN THE HANDLE IS  
PERPENDICULAR TO THE GAS FLOW DIRECTION.  
5. THIS APPLIANCE IS EQUIPPED WITH AN IGNITION  
DEVICE WHICHAUTOMATICALLY LIGHTS THE BURNER,  
DO NOT TRY TO LIGHT THE BURNER BY HAND.  
6. WAIT FIVE (5) MINUTES TO CLEAR OUT ANY GAS. THEN  
SMELL FOR GAS, INCLUDING NEAR THE FLOOR. IF YOU  
SMELL GAS,  
8. TURN POWER SWITCH TO “ON” POSITION.  
9. SET THE SYSTEM CONTROLLER TO DESIRED SETTING.  
10. IF THEAPPLIANCE WILL NOT OPERATE, FOLLOW THE  
INSTRUCTIONSTOTURNOFFGASTOTHEAPPLIANCE”  
AND CALL YOUR SERVICE TECHNICIAN OR GAS  
SUPPLIER.  
TO TURN OFF GAS TO APPLIANCE  
1. SET THE SYSTEM CONTROLLER TO THE LOWEST SETTING.  
2. TURN POWER SWITCH ON APPLIANCE TO “OFF” POSITION.  
3. TURN MAIN MANUAL GAS VALVE TO “OFF” POSITION, (FIGURE “B”). THE VALVE  
IS “OFF” WHEN THE HANDLE IS PERPENDICULAR TO THE GAS FLOW DIRECTION.  
25  
These jumpers are pre-set at the factory and should only be  
adjusted by a qualified service technician.  
CONTROL SYSTEM  
DESCRIPTION OF MULTI-STAGE FIRING SYSTEM  
The Display Board allows the end user to monitor water temperature,  
set-points, differentials, options, fault indications and error codes.  
Display Board pushbuttons labeled "ADJUST", "SELECT" AND  
The Central Control Board (CCB) is responsible for staging the  
Ignition Control Boards (ICB) and monitoring safety limit devices, "ENTER/RESET" enable the user to adjust set-points, differentials,  
post-circulate time, reset the cycle count and reset the control  
system during lock-out. Changes made to programmable features  
are stored in non-volatile memory.  
control of circulation pump, power vent, alarm output and IRI gas  
valves (only on IRI models). The thermostat also resides on the  
CCB with inputs available for inlet, outlet and tank temperature  
probes as well as an input for a remote 24 VAC thermostat. The  
CCB has a display interface which connects to the Display Board  
to show system status and failures. The CCB also has a set of DIP  
switches which allows the user to control several system  
parameters. (See Figure 14.)  
DIA-SCAN II DISPLAYBOARD OPERATING PROCEDURES  
The Display Board provides a user-friendly interface to the Central  
Control Board. With the Display Board, the user can control  
appliance functions and view the overall operating status of the  
appliance. If an error condition occurs, the Display Board will indicate  
the nature of the fault by illuminating a red LED. The display will  
further define the fault by illuminating a red LED corresponding to  
the stage on which the fault has occurred. Red and green LEDs  
are associated with each stage to indicate either a fault or normal  
operation. If the fault continues until the unit "locks out", the display  
will show a three digit code in addition to the red LEDs. (See Table  
19 for error code chart.) Under normal operating conditions, the  
four digit LED display on the Display Board will continuously illustrate  
the water temperature sensed at the inlet temperature probe. If dip  
Each stage requires an Ignition Control Board (ICB) which is  
responsible for controlling a combustion blower, hot surface igniter  
and gas valve. Each ICB is capable of monitoring gas valve power,  
gas valve relay, flame sense and igniter current. The ICB is  
designed to communicate with the Central Control Board (CCB).  
Each ICB consists of identical hardware and software. Each stage  
ICB is made unique through the use of circuit board jumpers which  
allow the user to control such variables as stage identification and  
blower/igniter usage. (See Figure 15 for jumper configurations.)  
DIP SWITCH CONFIGURATION TABLE  
SW1 OFF  
ON  
SELECTION:  
EITHER 3 OR 4 STAGE SYSTEM  
EITHER 3 OR 1  
WHETHER SYSTEM IS IRI OR  
STANDARD  
INLET OR TANKAS  
CONTROLLINGPROBE  
WHETHEREXTERNAL  
A
B
C
3 STAGE  
3 TRIALS  
NOIRI  
4 STAGE  
1 TRIAL  
IRI  
ON  
SW1  
GAS VALVE GAS VALVE  
INLET TANK  
D
E
1 2 3 4 5 6 7 8  
A B C D E F G H  
NO EXTERNAL EXTERNAL  
THERMOSTAT THERMOSTAT THERMOSTATIS USED  
F
G
H
OUTLET 210°F OUTLET 240°F OUTLETMAXIMUMTEMPERATURE  
190°F  
220°F  
MAX. SET-POINTTEMPERATURE  
EITHER °F OR °C FOR DISPLAYED  
TEMPERATURE  
DEGREES°F DEGREES°C  
Figure 14. Central Control Board's Dip Switch Configuration and Options  
26  
Figure 15. Ignition Control Board Jumper Settings  
Green Status Lights  
switch "D" on the Central Control Board is placed in the "ON"  
position, it will show the temperature at the tank probe. (See Figure  
14.) The push buttons on the Display Board allow the user to  
program and view several system parameters described in the  
following text. The Display Board is connected to the Central Control  
Board through a 6 conductor cable assembly with modular plug  
terminations. In addition, an 8 conductor modular jack on the Display  
Board allows for connecting a remote display board.  
Green LEDs indicate when a given stage has sensed flame and is  
in the heating state. They also are used to indicate when the  
Set-Point differential for a given stage is being viewed or adjusted.  
(See Figure 16.)  
STAGE 1: Stage One in Operation  
STAGE 2: Stage Two in Operation  
STAGE 3: Stage Three in Operation  
STAGE 4: Stage Four in Operation  
When power is applied to the Control System, the Display Board  
will initially run through a self-diagnostic test, and then display the  
inlet temperature. To display a specific setting or temperature,  
press the SELECT push-button until the appropriate LED is  
illuminated (see Figure 16). After 5 seconds, the Display Board  
will automatically revert to displaying the Inlet temperature. Press-  
ing the ENTER/RESET push-button will hold the display in the  
indicated mode until the SELECT push-button is pressed.  
Red Fault Lights  
The Red LEDs are illuminated to show faults and help in trouble  
shooting. There are three faults (High Gas Fail, LWCO and Power  
Vent Fail) listed as "Optional" which are only functional when the  
particular "Optional" equipment is included with the boiler. The red  
stage LEDs indicate on which stage a given fault has occurred.  
(See Figure 16.)  
With the display board, the user can make adjustments to many of  
the appliance’s control features. This includes the following:  
Options/Features Setting Procedures  
Blocked Flue: Blockage in Flue  
Probe Fail: One of the controlling Probes has failed  
Insufficient Air: Not enough Air to Close Switch  
Circulate Fail: Flow Switch Not Closed  
Gas Valve Fail: Relay for Gas Valve in Incorrect State  
High Limit: High Limit has been Exceeded  
Flame Fail: No Flame Sensed upon Ignition  
Igniter Fail: Igniter did not reach Minimum Amperage  
Low Gas Fail: Gas Pressure too low to Close Switch  
Set Appliance Stage Temperature Set-point Value  
Set Appliance Stage Switching Differential Value  
Select Appliance Post-Circulate Time  
Check Appliance Cycle Count  
View Last Error Encountered by Control  
Control the water temperature in a storage tank  
27  
Figure 16. Display Board  
Outlet Probe  
High Gas Fail: Gas Pressure at Manifold too High  
LWCO: Low water Cutoff activated. Not enough water.  
Power Vent Fail: Not Enough Air to Close Switch  
Stage One: Failure on Stage One  
The Outlet Temperature/ECO probe is located on the left side of the  
header and has two sets of wires embedded in it. The black wires  
sense the temperature at the probe. Their output is shown on the  
display screen when the "OUTLET" LED is illuminated. The red  
wires control the ECO (Emergency Cutoff) which shuts down the  
unit if the water temperature exceeds 250°F (121°C) and requires  
a manual reset of the boiler. The outlet probe functions as a  
automatically resettable high limit and is not considered a controlling  
probe on the boiler, which means it cannot be set to control the  
staging of the unit. Depending on the application of the boiler, the  
probe is set to one of two settings. In GW applications, the maximum  
Outlet Set Point is 210°F (99°C) and in GB applications it is 240°F  
(115°C). The Outlet probe Set Point can be adjusted between  
these two values using Dip Switch "F" on the Central Control Board  
inside the control box. (See Figure 14.)  
Stage Two: Failure on Stage Two  
Stage Three: Failure on Stage Three  
Stage Four: Failure on Stage Four  
Yellow Parameter Set Lights  
The five yellow parameter set lights allow the user to view system  
set points and options. In conjunction with the four green stage  
LEDs, the user can monitor and change settings on the various  
stages. (See Figure 16.)  
Inlet*:  
Temperature shown is Inlet Water  
Temperature.  
To view the current programmed temperature set-point for the Out-  
let Temperature probe:  
Outlet:  
Temperature shown is Outlet Water  
Temperature.  
1. Press the SELECT push-button on the display board until both  
the Set-Pt LED and Outlet Water Temperature LED (see  
Figure 16) are illuminated.  
Set-Point**:  
Indicated probe set-point is being  
displayed.  
Set-Point Differential:  
Standby:  
Shows differentials of each stage.  
Indicates Set-Point is Satisfied. Boiler  
in Idle State.  
2. The LED display will show the current set-point temperature.  
Note:  
Under no circumstances should the Outlet/ECO be set  
to exceed 210°F (99°C) in applications where the boiler  
is heating potable water. Failure to observe this will  
void the warranty.  
*Defaults to tank probe temperature when Dip Switch "D" on  
Central Control Board is Switched to the "ON" position.  
(See Figure 14.)  
Inlet Probe  
**Shows set-point temperatures for Inlet/Tank or Outlet in  
conjunction with yellow parameter lights. See temperature  
probe section below.  
The Inlet probe is located on the right side of the Inlet/Outlet header.  
It has one set of blue wires embedded in it which senses the  
temperature at the probe. The Inlet Probe is considered a controlling  
probe and can be used to control the staging of the unit. The inlet  
probe set-point is fully adjustable between the factory set minimum  
value of 80°F (25°C) and a user controlled maximum value which  
will depend on unit's application. In GW applications, the maximum  
Inlet Set-Point is 190°F (88°C) and in GB application it is 220°F  
(104°C). The Inlet probe Set-Point can be adjusted between these  
two maximum values using Dip Switch "G" on the Central Control  
Board which is located inside the control box. (See Figure 14.)  
TEMPERATURE PROBES  
All units come with two temperature probes connected to the Inlet/  
Outlet header. Additionally, an optional tank probe (thermistor type)  
or 24V thermostat/aquastat can be connected to the unit. The probes  
can be categorized as two types: controlling probes and safety  
limit probes. Controlling probes can control the staging of the  
boiler. Safety limit probes are used as resettable high limit switches.  
The two controlling probes are the inlet probe and the tank probe.  
The function and setting of the probes is further described in the  
following sections.  
To change or view the current programmed temperature set-point  
for the Inlet Temperature probe value:  
28  
1. Press the SELECT push-button on the display board until both be established. To facilitate proper operation and maximize  
the Set-Pt LED and Inlet Water Temperature LED (see appliance performance, each stage has a programmable  
Figure 16) are illuminated.  
2. The LED display will show the current set-point temperature.  
operating switching differential or “hysteresis” about the set point.  
This means a call for heat for a particular stage will become active  
3. Press and hold the ADJUST push-button. The displayed when the water temperature measured at the controlling  
temperature will either increase or decrease. To alternate temperature sensing probe drops to the set-point value minus the  
between increasing or decreasing the temperature, release switching differential value. It is necessary to set three set-point  
then press and hold the ADJUST push-button.  
4. When the desired set-point temperature is reached, release burner will remain on until the water temperature measured at  
the ADJUST push-button.  
controlling probe reaches the stage set-point value. The switching  
5. Press the ENTER/RESET push-button once, this enters the differential value is fully programmable from 0° F to 20°F (0°C to  
differential values for three stage units and four for four stage. The  
selected set-point temperature into controller memory.  
6. The appliance will now control the temperature to the desired  
set-point value.  
11°C) using the push-button(s) located on the Display Board.  
To change or view the current programmed switching differential:  
7. For setting the stage differentials, see the section labeled  
Procedure for Setting Stage Differential.  
1. Press the SELECT push-button on the display board until both  
the Set-Pt Diff. and green Stage One LED (see Figure 16) are  
illuminated.  
NOTE: The boiler must complete a full cycle in order for the  
new setting to take effect. If the unit is turned off prior 2. The LED display will show the current differential for stage  
to a complete cycle the setting will be lost and the  
previous setting will remain in effect.  
one.  
3. Press and hold the ADJUST push-button. The displayed value  
will either increase or decrease. To alternate between  
increasing or decreasing the differential, release then press  
and hold the ADJUST push-button.  
24 VAC System Controller (Optional)  
A 24 VAC thermostat/aquastat can be implemented as a system  
controller on Genesis units. The connection for such devices is 4. When the desired Set-Pt differential is reached, release the  
located in the 24 VAC junction box at the rear of the unit. A 24 VAC  
ADJUST push-button.  
thermostat/aquastat can only be used as an "On/Off" switch for the 5. Press the ENTER/RESET push-button once, this enters the  
unit. The actual controlling of the staging will be through either the  
inlet or tank probe. To use a 24 VAC system controller, dip switch "E"  
on the CCB must be switched to the "on" position. See Figure 14.  
selected set-point deferential into controller memory. To view  
the Set-Pt minus the Set-Pt differential, press and hold the  
"ENTER" push-button. This will be the "turn-on" temperature  
for Stage One and the "turn-off" temperature for Stage Two.  
6. Repeat steps 2 through 5 for the rest of the stages.  
Tank Probe (Optional)  
In addition to the Inlet and Outlet/ECO Probes, units can be 7. The appliance will now control temperature utilizing the  
optionally equipped with a tank Probe. The connection for the tank  
probe is located in the 24 VAC junction box at the rear of the unit.  
desired differentials.  
The tank Probe can be configured to control the staging of the unit. Example:  
See Tank Probe Installation section on page 17 for additional Application: Hydronic Heating  
information.  
Procedure for Setting Tank Probe Temperature  
Desired System Temperature: 185°F (85°C)  
Stage Differentials: 5°F (3°C) per Stage.  
Note: The user must first choose which probe is to control the  
If you have a GW hot water supply boiler, and have installed the tank staging of the unit. The controlling probe will be either the inlet or  
probe, below are the instructions on how to adjust the water tank probe. (If the tank probe is used to regulate loop temperature  
temperature set-point.  
in hydronic applications (GB Models), make sure it is located on  
the return side of the closed loop.) Use Dip Switch "D" on the  
1. Press the SELECT push-button on the display board until both Central Control Board to make this selection. See Figure 14.  
the Set-Pt LED and Inlet Water Temperature LED (see  
Figure 16) are illuminated.  
2. The LED display will show the current set-point temperature.  
Set the stage differentials using the procedure described in the  
Procedure for Setting Stage Differential section of the document.  
3. Press and hold the ADJUST push-button. The displayed Setting the control as described in the above example (5°F  
temperature will either increase or decrease. To alternate differentials for each stage) will give the following stage set-points.  
between increasing or decreasing the temperature, release  
then press and hold the ADJUST push-button.  
4. When the desired set-point temperature is reached, release  
the ADJUST push-button.  
5. Press the ENTER/RESET push-button once, this enters the  
selected set-point temperature into controller memory.  
6. The appliance will now control the temperature to the desired  
set-point value.  
Stage One  
Off Temperature: 185°F (85°C)  
On Temperature: 180°F (82°C)  
Stage Two  
Off Temperature: 180°F (82°C)  
On Temperature: 175°F (79°C)  
Stage Three  
Off Temperature: 175°F (79°C)  
On Temperature: 170°F (77°C)  
Stage Four  
7. For setting the stage differentials, see the section labeled  
Procedure for Setting Stage Differential.  
Procedure for Setting Stage Differential  
Off Temperature: 170°F (77°C)  
On Temperature: 165°F (74°C)  
Once the system control and set-point temperature has been  
entered, the switching differentials for the staging of the unit must  
29  
count for stage two will be displayed on the screen. Cycle  
counts for the other stages can be viewed in a similar fashion.  
5. To reset the cycle count to zero, press the ADJUST push-  
button. Press the ENTER/RESET push-button to  
successfully reset the cycle count. If the ENTER push-  
button is not pressed, the reset function will not be saved and  
the original cycle count will continue to increment on  
each gas valve operation.  
Procedure for Setting Pump Delay  
The Controller is factory set with a 45 second post circulate function.  
With the Display Board, the user has the capability to choose  
between a 45, 90, or 180 second post circulate time period, or turn  
the pump on continuously. This provides flexibility in selecting the  
post circulate time to meet specific installation requirements, and  
improves the efficiency of the circulating pump operation.  
6. The display will automatically return to illustrating the  
controlling probe temperature after five (5) seconds.  
To change or view the current programmed post-circulating time:  
Appliance Operating Sequence  
1. Press the SELECT push-button on the display board until the  
LED display reads "OP" (Options). See Figure 16.  
2. To enter into the options mode, press the ENTER/RESET  
push-button.  
3. The display will illustrate "Crcu". Enter this mode by  
pressing the ENTER/RESET push-button.  
4. The display will now illustrate the current post circulate time.  
Press the ADJUST push-button to select the desired post  
circulate time (45, 90, 180, "con").  
5. When you have selected the desired post circulate time mode,  
press the ENTER/RESET push-button once, this enters the  
selected post circulate time into controller memory.  
6. The display will automatically return to illustrating the  
controlling probe temperature after five (5) seconds.  
1. When power is applied to the control system, the Display Board  
will initially run through a self-diagnostic routine, and then go  
into its operating mode, displaying the temperature sensed  
at the Inlet probe.  
2. If the Central Control Board determines the actual water  
temperature at the controlling temperature probe is below the  
programmed temperature set-point minus the switching  
differential, and the thermostat circuit or tank probe circuit is  
closed, a call for heat is activated.  
3. The control then performs selected system diagnostic checks.  
This includes confirming the proper state of the ECO/High  
Limit device, flow switch*, and pressure switches.  
*Note: Correct water flow is vital to the operation of the boiler.  
See table 4 in the Installation manual for requirements on flow,  
head loss and heat exchanger pressure drop.  
Last Error Mode  
In this mode, the Display Board will illustrate the last error which  
caused the unit to "lock-out". When this mode is entered the three  
digit failure code that was in memory last will be displayed.  
(See table 19 for error codes.) For example, if the appliance  
"locked-out" due to insufficient air on stage one, the display will  
show 041. To enter into this mode, perform the following steps:  
4. If all checks are successfully passed, the circulating pump  
circuit is energized. Once the flow switch has closed, all  
combustion blowers will energize for a 30 second pre-purge  
cycle.  
5. When the pre-purge cycle is complete, all blowers except stage  
1 will drop out. Power is applied to the stage 1 ignitor element  
for the ignitor warm-up period.  
1. Press the SELECT push-button on the display board until the  
LED display reads "OP" (Options). See Figure 16.  
2. To enter into the options mode, press the ENTER/RESET  
push-button.  
3. The display will illustrate "Crcu". Press the SELECT  
push-button until the display illustrates "Ler". Enter this mode  
by pressing the ENTER/RESET push-button.  
4. The display will illustrate the last error detected by the control.  
5. The display will automatically resort to illustrating the  
controlling probe temperature after five (5) seconds.  
6. The control will verify ignitor current. After the verification, the  
gas valve will open, allowing gas to enter the burner.  
7. After an additional 1 second, the control will monitor the flame  
sense probe to confirm a flame is present. If a flame is not  
verified within 4 seconds, the gas valve is immediately closed.  
The control will initiate an 15 second inter-purge period and  
return to step 2, unless dip switch "B" is in the "ON" position,  
see fig. 14, in which case it will proceed to "lock-out".  
8. If a flame is confirmed, stage two will be activated. The blower  
associated with stage two will start. Once the blower has  
been proven, igniter two will begin its warm-up period.  
(This is true on all units except the 1000 which has only one  
igniter.) After the igniter current has been proven, stage two  
will begin a trial for ignition.  
9. Stage three will activate after flame is proven on stage two. If  
applicable, the blower associated with stage three will begin.  
Once the blower has been proven, a trial for ignition will begin  
on stage three. If flame is not proven, there will be a 15  
second interpurge on stages with an associated blower. The  
boiler will then begin additional trials for ignition. On stages  
without an associated blower, a five second delay will occur  
before the gas valves are opened for additional trials for  
ignition.  
Display Stage Cycle Count  
The Central Control Board counts the number of cycles each stage  
of the appliance has operated by counting how many times the gas  
valve(s) are energized. To check the cycle count for each stage,  
perform the following procedure:  
1. Press the SELECT push-button on the display board until the  
LED display reads "OP" (Options). See Figure 16.  
2. To enter into the options mode, press the ENTER/RESET  
push-button.  
3. The display will illustrate "Crcu". Press the SELECT  
push-button until the display illustrates "CC". Enter this mode  
by pressing the ENTER/RESET push-button.  
4. The display will now illustrate the current number of cycles  
stage one has fired. Notice that the green Stage One LED is  
illuminated. Pressing the ENTER/RESET button again will  
cause the green Stage Two LED to illuminate and the cycle  
Note: Stages on which no blower or igniter is present will  
bypass the blower and igniter proving periods. The gas valves will  
open five seconds after a call for heat is initiated on the stage.  
10. All stages will remain running until the set point for a given  
stage is satisfied. If all stages are initiated, stage four will  
30  
NOTE: Cleaning of main burners.  
Shut off all gas and electricity to unit.  
1. Remove main burners from unit.  
drop out first followed by stages three, two and one. To achieve  
maximum efficiency, stages will reignite if the system water  
temperature drops below the stage Set Point minus the Set  
Point Differential.  
Note: Once a stage is satisfied, the blower associated with that 2. Check that burner venturi and ports are free of foreign matter.  
stage will allow a 25 second postpurge before it deactivates.  
3. Clean burners with bristle brush and/or vacuum cleaner.  
DO NOT distort burner ports.  
11. Once all of the stages have been satisfied, the pump will run  
for the programmed post-circulate cycle (factory default 45  
seconds). See Procedure for Setting Pump Delay on page 30  
of the manual.  
4. Reinstall burners in unit. Ensure that all the screws on the  
burner flange are tightened securely so that the gasket will  
provide a good seal. Also, ensure that each orifice is centered  
with the venturi opening of every burner. The washer of the  
orifice must be inserted a minimum of 1/4" into the burner  
tube. This is critical for proper operation. See Figure 18.  
12. The control now enters the idle state. This is indicated on the  
display by the "Standby" LED. The control will continue to  
monitor temperature and the state of other system devices. If  
the water temperature at the designated system controller  
drops below the set-point value minus the switching  
differential, and the thermostat circuit or tank probe circuit  
closes, the control will return to step 2 and repeat the entire  
operating cycle. During this idle state, if the control detects an  
improper operating state for external devices such as the ECO  
switch, air pressure switch, gas pressure switch, etc., the  
appropriate LED(s) on the Display Board will illuminate  
indicating the nature of the fault.  
5. Also check for good flow of combustion and ventilating air to  
the unit.  
This is a powered burner and the flame is not supposed to be on  
the burner. The flame should be just above the burner deck  
approximately 1/8” and blue in color (see Figure 17).  
Visually check flame characteristics through the view port located  
under the left-hand header on the boiler. Figure 17 shows the  
normal flame condition. Also, refer to the flame label on the unit  
(adjacent to the view port).  
PREVENTATIVE MAINTENANCE  
These boilers are designed to give many years of efficient and  
satisfactory service when properly operated and maintained. To  
assure continued good performance, the following  
recommendations are made.  
The area around the unit should be kept clean and free from lint  
and debris. Sweeping the floor around the boiler should be done  
carefully. This will reduce the dust and dirt which may enter the  
burner and heat exchanger, causing improper combustion and  
sooting.  
MAIN BURNERS  
Check main burners every three months for proper flame  
characteristics.  
The main burner should display the following characteristics:  
Provide complete combustion of gas.  
Cause rapid ignition and carry over of flame across entire burner.  
Give reasonably quiet operation during initial ignition, operation  
and extinction.  
Figure 18. Orifice Insertion  
After placing the boiler in operation, check the ignition system safety  
shut-off devices for proper operation. To accomplish this with the  
main burners operating, close the valve on the manifold. Within  
four seconds the main burners should extinguish. If this does not  
occur immediately, discontinue gas supply by closing main manual  
shut-off and call a qualified serviceman to correct the situation. If  
the burners extinguish, then light boiler in accordance with lighting  
and operating instructions.  
Cause no excessive lifting of flame from burner ports  
(see Figure 17).  
If the preceding burner characteristics are not evident, check for  
accumulation of lint or other foreign material that restricts or blocks  
the air openings to the burner or boiler.  
For installations above 4,500 feet (1350 m), refer to HIGHALTITUDE  
INSTALLATIONS in the installation section.  
THE FLOW OF COMBUSTION AIR TO THE BOILER MUST NOT BE  
OBSTRUCTED.  
THE BOILER AREA MUST BE KEPT CLEAR AND FREE FROM  
COMBUSTIBLE MATERIALS, GASOLINEAND OTHER FLAMMABLE  
VAPORSAND LIQUIDS.  
Figure 17. Normal Flame Characteristics  
Any safety devices including low water cutoffs used in conjunction  
31  
1. Turn off the electrical power, and manual gas shut-off.  
Allow boiler parts to cool before disassembly.  
2. Remove the vent pipe.  
Check parts and chimney for obstructions and clean as  
necessary.  
with this boiler should receive periodic (every six months) inspection  
to assure proper operation. A low water cutoff device of the float  
type should be flushed every six months. Periodic checks, at least  
twice a year, should be made for water and/or gas leaks.  
3. Remove burners from boiler and other metal parts as required  
to clean as necessary.  
More frequent inspections may be necessary depending on water  
conditions.  
Refer to parts list supplied with this manual for  
disassembly aid.  
The boiler-mounted gas and electrical controls have been designed  
to give both dependable service and long life. However, malfunction  
can occur, as with any piece of equipment. It is therefore  
recommended that all components be checked periodically by a  
qualified serviceman for proper operation.  
4. Clean and reinstall the parts removed in steps 2 and 3.  
Be sure the vent pipe has a minimum upward pitch of 1/4"  
per foot (2 cm/m) of length and is sealed as necessary.  
5. Restore electrical power and gas supply to boiler.  
Check for gas leaks and proper boiler and vent operation.  
HEATEXCHANGERPREVENTIVEMAINTENANCE  
RELIEFVALVE  
In most water supply systems some solids exist. As the water is  
heated, these tend to drop out depositing as scale or lime. This  
scale must be removed before the heat exchanger tubes become  
blocked.  
The safety relief valve should be opened at least twice a year to  
check its working condition. This will aid in assuring proper  
pressure relief protection. Lift the lever at the top of the valve several  
times until the valve seats properly and operates freely.  
DANGER  
CAUTION  
THE WATER PASSING OUT OF THE VALVE DURING CHECKING  
OPERATION MAY BE EXTREMELY HOT. BEFORE OPERATING  
RELIEF VALVE, MAKE SURE DRAIN LINE IS INSTALLED TO DIRECT  
DISCHARGE TO A SAFE LOCATION SUCH AS AN OPEN DRAIN,  
TOAVOID SCALDING OR WATER DAMAGE.  
LIME ACCUMULATION CAN REDUCE THE LIFE OF THE  
EQUIPMENT, REDUCE EFFICIENCYAND WASTE FUEL. BOILER  
FAILURE DUE TO LIME OR SCALE BUILDUP VOIDS THE  
WARRANTY.  
DELIMING  
WARNING  
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAILTO  
SHUT OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO  
THE APPLIANCE.  
The amount of calcium carbonate (lime) released from water is in  
direct proportion to water temperature and usage. The higher the  
water temperature or water usage, the more lime deposits are  
dropped out of the water. This is the lime scale which forms in  
pipes, boilers and on cooking utensils.  
COMBUSTIONAIR FILTER  
If the combustion air supply to the boiler contains dust, dirt, drywall  
dust etc. a filter must be installed. Air filter is not supplied with the  
boiler as shipped from the factory. The installer must provide a  
filtering system in the air inlet to the boiler if dust, dirt or construction  
dirt can be pulled into the boiler through the inlet air piping.  
The usage of water softening equipment greatly reduces the  
hardness of water. However, this equipment does not always  
remove all of the hardness (lime). For this reason it is recommended  
that a regular schedule for deliming be maintained.  
BLOWER COMPARTMENT  
The time between cleaning will vary from two to six months  
depending upon water conditions and usage. A change of  
approximately 5oF (3°C) in the normal temperature rise through the  
boiler is usually an indication that scale should be removed. For  
long life, copper or brass is recommended for all valves, pipe and  
fittings.  
The blower compartment should be cleaned annually to remove  
any dirt and lint that may have accumulated in the compartment or  
on the blower and motor. Buildups of dirt and lint on the blower and  
motor can create excessive loads on the motor resulting in higher  
that normal operating temperatures and possible shortened service  
life.  
TUBECLEANINGPROCEDURE  
MECHANICAL REMOVAL OF DEPOSITS  
VENTINGMAINTENANCE  
Establish a regular inspection schedule, the frequency depends  
on the local water conditions and severity of service. Do not let the  
tubes clog up solidly. Clean out deposits over 1/16" (1.6 mm)  
thickness.  
It is recommended that the intake and exhaust piping of the  
appliance be checked every 6 months for dust, condensate leakage,  
deterioration and carbon deposits.  
WARNING  
To service heat exchanger tubes remove return header casting,  
side opposite the water connections. Use a U.S. standard 5/8"  
deep socket ratchet to remove the nuts, exposing the tube ends.  
DO NOT USE A NYLON BRUSH OR OTHER STATIC CREATING  
MATERIAL TO CLEAN DUST AND CARBON DEPOSITS FROM  
HEATING SURFACES AND VENT. SUCH DEPOSITS ARE  
FLAMMABLEAND MAY BE IGNITED BY STATIC ELECTRICITY. USE Inspect to ensure tubes are free of scale and deposits. If scaled,  
AMETAL BRUSH TO MINIMIZE THE DANGER OF EXPLOSION.  
remove deposits with a stiff wire brush or mechanical tube cleaner  
to bare metal. Reinstall return header casting. Flush system.  
Qualified serviceman should follow this procedure when the boiler's  
intake and exhaust piping need cleaning:  
Note: Removal of the heat exchanger is not required.  
32  
Display Board contains sixteen (16) red fault LED indicators to  
help pinpoint the source of failures. In addition, the display will  
inform the user on which stage the failure occurred by illuminating  
a red Stage LED. In cases where the problem persists to lockout,  
the appropriate red LEDs will remain illuminated and a three digit  
error code will flash on the display screen. A summary of error  
codes is given in table 19. The error codes are broken into two  
categories: hard lockouts and soft lockout.  
CAUTION  
IF HEAT EXCHANGER MAINTENANCE REQUIRES TUBING  
REPLACEMENT, SPECIAL PROVISIONS SHALL BE TAKEN TO  
ENSURE THAT THE DAMAGED TUBES ARE CAREFULLY  
REMOVED.  
REPLACEMENT TUBES MUST BE PROPERLY INSTALLED AND  
EXPANDED INTO THE ROLLED TUBE TUB.  
Hard Lockouts:  
OVER-ROLLING, MISALIGNMENT OF TUBES OR IMPROPER  
TIGHTENING OF THE ASSEMBLY MAY RESULT IN LEAKS OR  
DAMAGE TO THE HEAT EXCHANGER. CONTACT YOUR  
A. O. SMITH DEALER FOR DETAILED INSTRUCTIONS.  
Hard lockouts require a manual reset accomplished by pressing  
the Enter/Reset push-button on the Display Board. Cycling the  
power "OFF" and "ON" will not reset the control.  
Soft Lockouts:  
REPLACEMENT PARTS  
Soft Lockouts also require a manual reset accomplished by  
pressing the Enter/Reset push-button on the display board.  
However, under a soft lockout condition, the control will re-initiate  
an ignition process after one (1) hour provided the call-for-heat is  
still present and will continue every hour until the unit is either reset  
or ignites.  
Replacement parts may be ordered through A. O. Smith dealers,  
authorized servicers or distributors. Refer to the Yellow Pages for  
where to call or contact (in United States) the A. O. Smith Water  
Products Company, 5621 West 115th Street, Alsip, IL 60803,  
1-800-433-2545 or (in Canada) A. O. Smith Enterprises Ltd., 768  
Erie Street, Stratford, Ontario, Canada N5A 6T3, 519-271-5800.  
When ordering parts be sure to state the quantity, part number and  
description of the item including the complete model and serial  
number as it appears on the product. Refer to the parts lists for  
more information.  
A description of the red fault LEDs and their corresponding  
functions are as follows.  
LED  
Controller Function  
For Technical Assistance call A. O. Smith Technical Information  
Center at 1-800-527-1953.  
Blocked Flue  
Indicates a blockage or interference at the  
appliance flue.  
Temp. Probe Fail Indicates failure at one of the temperature  
probes. Unit will "lock-out" only if controlling  
probe fails.  
TROUBLESHOOTING  
Before any extensive troubleshooting, ensure that:  
Insufficient Air  
Indicates air pressure was too low to create  
a sufficient differential to close the  
differential pressure switch.  
Power (120 VAC) is supplied to the appliance.  
System control (tank probe, thermostat, etc.) is calling for  
appliance operation (call for heat).  
Circulate Fail  
Gas Valve Fail  
Indicates water flow was too low to close  
the flow switch.  
Monitors Gas Valve relay output. LED is ON  
when the output relay supplying power to  
the gas valve(s) is open.  
Monitors ECO in the Outlet Temperature  
probe. LED is ON when the ECO is open.  
Monitors the Flame Sense Rod. LED is ON  
when a signal from the flame rod is not  
sufficient to indicate flame.  
Indicates igniter current was too low to meet  
minimum value which allows trial for  
ignition to continue.  
Other contacts (switches) are closed (low water cutoff, flow  
switch, limit controls, pressure switches, etc.)  
Gas supply pressure is within the maximum and minimum  
operating ranges listed on the appliance rating plate/label.  
Appliance is wired according to wiring diagram.  
High Limit  
Flame Fail  
NOTE: Shorting the thermostat wiring to ground in the 24 volt  
circuit will blow the 3 amp fuse.  
All wire terminals/connectors are firmly attached to valves,  
modules, switches, limit controls, etc.  
There has been no damage caused by freezing, inoperative  
pumps, etc.  
Igniter Fail  
Low Gas Fail  
High Gas Fail*  
LWCO Fail*  
Inlet gas pressure is not sufficient to close  
gas pressure switch.  
Manifold gas pressure is has exceeded  
designed maximum value.  
Indicates water level in system is too low for  
safe operation.  
CAUTION  
MAKE SURE POWER IS DISCONNECTED FROM MAIN BREAKER  
BEFORE SERVICING.  
CAUTION  
Power Vent Fail* Air pressure at Power Vent Switch is not  
sufficient for safe operation.  
LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN  
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE  
IMPROPER FUNCTIONING OF UNIT RESULTING IN PROPERTY  
DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.  
*Optional Equipment - LEDs will illuminate only if equipment is  
connected to boiler.  
TROUBLESHOOTING IGNITION SYSTEM  
Upon lockout, manually push the ENTER/RESET button on the  
display panel to restart the boiler.  
The control system has several features to aid in troubleshooting  
problems which may occur during operation. If a fault occurs, the  
Verify proper operation after servicing.  
33  
Table 19. Error Code Chart  
FAULT  
GENESIS II CONTROL - FAULT OPERATION  
ERROR CODES  
LOCKOUT  
COMMUNICATIONS FAULT (CCB TO ICB)  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
001  
002  
003  
004  
HARD  
HARD  
HARD  
HARD  
ECO/HIGH LIMIT:  
010  
HARD  
NO GAS VALVE POWER SENSED  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
LWCO  
CIRCULATE FAULT (FLOW SWITCH)  
011  
012  
013  
014  
020  
030  
HARD  
HARD  
HARD  
HARD  
HARD  
SOFT  
INSUFFICIENT AIR (AIR PRESSURE SWITCH)  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
BLOCKED FLUE  
POWER VENT  
041  
042  
043  
044  
060  
070  
SOFT  
SOFT  
SOFT  
SOFT  
SOFT  
SOFT  
IGNITER FAILURE  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
081  
082  
083  
084  
090  
HARD  
HARD  
HARD  
HARD  
HARD  
LOW GAS FAILURE  
HIGH GAS FAILURE  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
101  
102  
103  
104  
HARD  
HARD  
HARD  
HARD  
GAS VALVE RELAYFAILURE  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
111  
112  
113  
114  
HARD  
HARD  
HARD  
HARD  
FLAME FAILURE  
STAGE 1:  
STAGE 2:  
STAGE 3:  
STAGE 4:  
121  
122  
123  
124  
HARD  
HARD  
HARD  
HARD  
PROBE FAULTS  
OUTLET PROBE  
INLET PROBE  
REMOTE PROBE  
IRI GAS VALVE FAILURE  
CPU FAULT  
131  
132  
133  
140  
210  
HARD  
HARD  
HARD  
HARD  
HARD  
For additional information please refer to the User’s Manual supplied with the boiler or contact:  
A.O. Smith Technical Services 7 a.m. to 7 p.m. Central Time at: 1-800-527-1953  
Our Internet Site is another source of information 24 hours a day.  
34  
NEW BOILER LIMITED WARRANTY  
A. O. Smith Corporation, the warrantor, extends the following LIMITED WARRANTY to the owner of this hydronic boiler:  
1. If within TEN years after initial installation of the boiler, the heat exchanger shall prove upon examination by the warrantor to be defective in material  
or workmanship, the warrantor, at his option, will exchange or repair such part or portion. This term is reduced to FIVE years if this boiler is used for  
volume hot water supply purposes other than hydronic space heating.  
a. This warranty is extended to the owner for all other parts or portion during the FIRST year following initial installation of this boiler.  
b. The warranty on the repair or replacement of the part or portion will be limited to the unexpired term of the original warranty.  
2. CONDITIONS AND EXCEPTIONS  
This warranty shall apply only when the boiler is installed in accordance with local plumbing and building codes, ordinances and regulations, the  
printed instructions provided with it and good industry practices. In addition, an appropriately sized safety relief valve certified to the ASME Boiler  
and Pressure Vessel Code must have been installed and fresh water used for filling and makeup purposes;  
a. This warranty shall apply only when the boiler is used:  
(1) at temperatures not exceeding the maximum setting of its operative and/or high limit control;  
(2) at water pressure not exceeding the working pressure shown on the boiler;  
(3) when filled with boiler water, free to circulate at all times and with the heat exchanger free of damaging scale deposits;  
(4) in a noncorrosive and non-contaminated atmosphere;  
(5) in the United States, its territories or possessions, and Canada;  
(6) at a water velocity flow rate, not exceeding or below the Boiler's designed flow rates;  
b. Any accident to the boiler, any misuse, abuse (including freezing) or alteration of it, any operation of it in a modified form will void this warranty.  
3. SERVICEAND REPAIR EXPENSE  
Under this limited warranty the warrantor will provide only a replacement part. The owner is responsible for all other costs. Such costs may include  
but are not limited to:  
a. Labor charges for service removal, repair or reinstallation of the component part;  
b. Shipping, delivery, handling, and administrative charges for forwarding the replacement part from the nearest distributor and returning the  
claimed defective part to such distributor.  
c. All cost necessary or incidental for any material and/or permits required for installation of the replacement.  
4. LIMITATIONS ON IMPLIED WARRANTIES  
Implied warranties, including any warranty of merchantability imposed on the sale of this boiler under state law are limited to one (1) year duration  
for the boiler or any of its parts. Some states or provinces do not allow limitations on how long an implied warranty lasts, so the above limitation may  
not apply to you.  
5. CLAIM PROCEDURE  
Any claim under the warranty should be initiated with the dealer who sold the boiler, or with any other dealer handling the warrantor’s products.  
If this is not practical, the owner should contact:  
U.S. Customers  
Canadian Customers  
A. O. Smith Water Products Company  
5621 West 115th Street  
Alsip, IL 60803  
A. O. Smith Enterprises Ltd.  
P. O. Box, 310 - 768 Erie Street  
Stratford, Ontario N5A 6T3  
Telephone: (519) 271-5800  
Telephone: 800 323-2636  
a. The warrantor will only honor replacement with identical or similar parts thereof which are manufactured or distributed by the warrantor.  
b. Dealer replacements are made subject to in-warranty validation by warrantor.  
6. DISCLAIMERS  
NO OTHER EXPRESS WARRANTY HAS BEEN OR WILL BE MADE ON BEHALF OF THE WARRANTOR WITH RESPECT TO THE BOILER OR THE  
INSTALLATION, OPERATION, REPAIR OR REPLACEMENTOFTHE BOILER. THE WARRANTOR SHALLNOTBE RESPONSIBLE FOR WATER DAMAGE,  
LOSSOFUSEOFTHEUNIT, INCONVENIENCE, LOSSORDAMAGETOPERSONALPROPERTYOROTHERCONSEQUENTIALDAMAGE.THEWARRANTOR  
SHALLNOT BE LIABLE BYVIRTUE OF THIS WARRANTYOR OTHERWISE FOR DAMAGE TOANYPERSONS OR PROPERTY, WHETHER DIRECT OR  
INDIRECT,AND WHETHERARISING IN CONTRACTORTORT.  
a. Some states or provinces do not allow the exclusion or limitation of the incidental or consequential damage, so the above limitations or exclusions  
may not apply to you.  
b. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state or province to province.  
Fill in the following for your own reference. Keep it. Registration is not a condition of warranty. The model and serial number are found on the boiler’s  
rating plate.  
Owner_____________________________________________________________________________________________________________________  
Installation Address___________________________________________________________________________________________________________  
City and State or Province_____________________________________________________Postal/Zip Code____________________________________  
Date Installed__________________________Model No.______________________________Serial No.________________________________________  
Dealer’s Name_______________________________________________________________________________________________________________  
Dealer’s Address________________________________________________________________Phone No. ____________________________________  
FILLIN WARRANTYAND KEEPFOR FUTURE REFERENCE  
37  
REPLACEMENT PARTS  
5621 W. 115TH STREET, ALSIP, IL 60803  
Phone: 800-433-2545 Fax: 800-433-2515  

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