A.O. Smith 200 Series User manual

1
PRINTED IN U.S.A. 2526 0501
COPPER BOILERS FOR
HYDRONIC HEATING AND
HOT WATER SUPPLY
CAUTION
TEXT PRINTED OR OUTLINED IN RED CONTAINS
INFORMATION RELATIVE TO YOUR SAFETY.
PLEASE READ THOROUGHLYBEFORE INSTALLING
ANDUSINGTHISAPPLIANCE.
PART NO. 211257-000 REV. 0
ADIVISIONOFA.O.SMITHCORPORATION
ELPASO,TX.,MCBEE,SC., RENTON,WA.,
STRATFORD-ONTARIO, VELDHOVEN-THENETHERLANDS
www.hotwater.com
PLACETHESEINSTRUCTIONSADJACENTTOBOILERAND
NOTIFYOWNERTOKEEPFORFUTUREREFERENCE.
•Installation
•Operation
•Maintenance
•Limited Warranty
Instruction Manual
GB/GW MODELS:
1000, 1300, 1500, 1850, 2100, 2500
SERIES200,201
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.
ThankYou
for buying this cost
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
importantsafety and operating instructionsas well
asthe WARNINGS and CAUTIONS.
CONTENTS PAGE
ROUGH-INDIMENSIONS/CAPACITIES .............2 - 3
FOREWORD .....................................................4 - 5
FEATURES/CONTROLS ................................... 5 - 6
INSTALLATIONINSTRUCTIONS ................... 6 - 22
VENTING ....................................................... 8 - 14
SYSTEMINSTALLATION ..............................15 - 19
HYDRONICINSTALLATION ..........................15 - 17
HOTWATER SUPPLYINSTALLATION .........17 - 19
GASCONNECTIONS ....................................20 - 21
OPERATION ................................................ 22 - 23
LIGHTINGANDOPERATING .........................24 - 25
CONTROLSYSTEM .................................... 26 - 31
PREVENTATIVE MAINTENANCE ................ 31 - 33
TROUBLESHOOTING ..................................33 - 34
LIMITEDWARRANTY .......................................... 35
WIRINGDIAGRAM/SCHEMATIC .................. 36 - 37
•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:
•Extinguish any open flame.
•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.

2
ROUGH-INDIMENSIONS
Figure 1.
IMPORTANT!
Refer to "Installation Clearances" section of manual
(page 7) for recommended service clearances prior
to boiler placement.
TOP VIEW
LEFTSIDE
TABLE 2. ROUGH - IN DIMENSIONS
ABCD EF
Model Inches cm Inches cm Inches cm Inches cm Inches cm Inches cm
GW/GB-1000 14.1 35.8 12.2 31.0 40.3 102.4 31.6 80.3 26.0 66.0 46.8 118.9
GW/GB-1300 24.8 63.0 12.2 31.0 40.3 102.4 31.6 80.3 39.3 99.8 57.3 145.5
GW/GB-1500 30.2 76.7 12.2 31.0 40.3 102.4 31.6 80.3 44.6 113.3 64.3 163.3
GW/GB-1850 27.7 70.4 11.2 28.4 43.0 109.2 32.3 82.0 44.0 111.8 78.3 198.9
GW/GB-2100 31.0 78.7 11.2 28.4 43.0 109.2 32.3 82.0 49.5 125.7 85.3 216.7
GW/GB-2500 38.1 96.8 10.5 26.7 43.0 109.2 32.3 82.0 56.5 143.5 99.3 252.2
Input Exhaust Inlet
TABLE1:GAS AND ELECTRICAL CHARACTERISTICS
Manifold Pressure Electrical Characteristics
Model Type of Gas Inches W.C. kPa Volts/Hz Amperes
GW/GB-1000
thru 2500 NATURAL 3.5 0.87 120/60 30
GW/GB-1000
thru 2500 PROPANE 10 2.49 120/60 30
All Models - Maximum Supply Pressure: 14.0 In. W.C. (3.49 kPa)
Minimum Supply Pressure Natural Gas: 6.0 In. W.C. (1.22 kPa)
Minimum Supply Pressure Propane Gas: 11.0 In. W.C. (2.74 kPa)
Minimum Pressures must be maintained under both load and no load
(static and dynamic) conditions.
REARVIEW
FRONTVIEW
BTU/Hr. KW BTU/Hr. KW Vent Diameter Vent Diameter Water Conn. Gas Inlet
Model Natural Gas Natural Gas Propane Gas Propane Gas Inches cm Inches cm Size
GW/GB-1000 990,000 289.95 990,000 289.95 10 25.4 8 20.3 21/2NPT 2NPT
GW/GB-1300 1,300,000 380.74 1,300,000 380.74 12 30.5 10 25.4 21/2NPT 2NPT
GW/GB-1500 1,500,000 439.31 1,500,000 439.31 12 30.5 10 25.4 21/2NPT 2NPT
GW/GB-1850 1,850,000 541.82 1,850,000 541.82 14 35.6 10 25.4 21/2NPT 21/2 NPT
GW/GB-2100 2,100,000 615.04 2,100,000 615.04 14 35.6 12 30.5 21/2NPT 21/2 NPT
GW/GB-2500 2,490,000 729.26 2,490,000 729.26 16 40.7 12 30.5 21/2NPT 21/2 NPT

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TABLE4: HEATEXCHANGERPRESSURE DROP
GB Models-Flow, Head Loss and Temperature Rise
20 Deg. F Rise 30 Deg. F Rise 40 Deg. F Rise Maximum Flow Rate Minimum Flow Rate
GPM PD-FT GPM PD-FT GPM PD-FT GPM PD-FT Deg.F GPM PD-FT Deg. F
MODEL Head Head Head Head Rise Head Rise
GB - 1000 83.16 5.1 55.4 2.7 41.6 1.5 154 12.2 11 42 1.5 40
GB - 1300 109.2 7.2 72.8 4.2 54.6 3.2 154 14.5 14 55 3.2 40
GB - 1500 126 10.1 84 6.3 63 4.3 154 16.3 17 64 4.3 40
GB - 1850 154 18.5 103.6 10.1 77.7 6.4 154 18.5 20 78 6.4 40
GB - 2100 n/a n/a 117.6 14.5 88.2 8.3 154 21.3 23 89 8.3 40
GB - 2500 n/a n/a 139.4 18.5 104.6 11.6 154 23.2 28 105 11.6 40
TABLE3: RECOVERYCAPACITIES
Temperature Rise - Degrees °F (°C)
InputRating Gal/Liter 40°F 50°F 60°F 70°F 80°F 90°F 100°F 110°F 120°F 130°F
MODEL BTU/Hr. (kW) per Hr. (22.2°) (27.7°) (33.3°) (38.8°) (44.4°) (50°) (55.5°) (61.1°) (66.7°) (72.2°)
GW - 1000 990,000 (290.1) LPH 9526 7620 6350 5443 4763 4234 3810 3462 3175 2930
GPH 2520 2016 1680 1440 1260 1120 1008 916 840 775
GW - 1300 1,300,000 (380.9) LPH 12508 10006 8339 7148 6256 5560 5005 4547 4169 3848
GPH 3309 2647 2206 1891 1655 1471 1324 1203 1103 1018
GW - 1500 1,500,000 (439.5) LPH 14432 11548 9620 8248 7216 6415 5772 5247 4812 4442
GPH 3818 3055 2545 2182 1909 1697 1527 1388 1273 1175
GW - 1850 1,850,000 (542.0) LPH 17800 14239 11865 10172 8902 7912 7122 6471 5935 5477
GPH 4709 3767 3139 2691 2355 2093 1884 1712 1570 1449
GW - 2100 2,100,000 (615.3) LPH 20204 16163 13472 11548 10104 8981 8082 7348 6736 6218
GPH 5345 4276 3564 3055 2673 2376 2138 1944 1782 1645
GW - 2500 2,490,000 (729.6) LPH 23958 19168 15971 13691 11979 10648 9582 8713 7987 7371
GPH 6338 5071 4225 3622 3169 2817 2535 2305 2113 1950
Note: GW models (GB optional) are equipped with pumps capable of handling 50 equivalent feet
(15.2 m) of normal pipe fittings.

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PRECAUTIONS
IF THE UNIT IS EXPOSED TO THE FOLLOWING, DO NOT
OPERATE UNTIL ALL CORRECTIVE STEPS HAVE BEEN MADE
BYA QUALIFIEDSERVICEMAN:
1. EXPOSURETOFIRE.
2. IFDAMAGED.
3. FIRINGWITHOUTWATER.
4. SOOTING.
IFTHE BOILERHASBEENEXPOSEDTOFLOODING,ITMUSTBE
REPLACED.
LIQUIDPETROLEUM MODELS
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.
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
made.
At times you may not be able to smell an LP gas leak. One cause
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.
IFYOU EXPERIENCEANOUTOFGAS SITUATION, DO NOTTRY
TO RELIGHT APPLIANCES YOURSELF. Call your local service
agent. Only trained LP professionals should conduct the required
safety checks in accordance with industry standards.
HIGHALTITUDEINSTALLATION
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.
GENESIS BOILERS ARE EQUIPPED WITH SELF-REGULATING
PREJETORIFICESWHICHAUTOMATICALLYCOMPENSATE FOR
HIGHER ELEVATIONS AND ADJUST THE APPLIANCE'S INPUT
RATEACCORDINGLY,MAKINGITUNNECESSARYTOREPLACE
ORIFICES FOR HIGH ALTITUDE (UP TO 4,500 FEET ONLY.
CONSULT THE FACTORY FOR HIGHERALTITUDES.)
Some utility companies derate their gas for altitude. You should
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.
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.
FOREWORD
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.
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.
Thefactorywarrantywillbevoid if the boiler(s) havebeen improperly
installed or operated.
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.
In the absence of local codes, the installation must comply with
the latest editions.
In the United States:
TheNationalFuel Gas Code,ANSIZ223.1/NFPA54 and the National
Electric Code, NFPA 70.
In Canada:
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.
GROUNDINGINSTRUCTIONS
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.
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
YOURBOILERIS NOTDESIGNED TOOPERATE 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
VENTINGRESULTINGIN PREMATUREDAMAGE,WHICH COULD
RESULT IN SERIOUS PERSONAL INJURY OR DEATH.
FOR SYSTEMS THAT USE LARGE VOLUMES OF COLD WATER
ORSYSTEMSUTILIZINGHEAVYWATERDRAWS,CONDENSATION
CANBEPREVENTEDBYUSINGABYPASS LOOP.
CORRECTGAS
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.

5
Example: A Genesis boiler is rated at 1,300,000 Btu/hr. input at sea
level. Atanaltitude of 5,000 (1500m), theprejetorificeswill decrease
the input rate by 20% (= 4% x 5) to a new rating of 1,040,000 Btu/hr.
(= 80% x 1,300,000 Btu/hr.) The input reduction is achieved by the
prejet orifices through self-regulation.
FEATURES/CONTROLS
MULTI-STAGE FIRINGANDCONTROLSYSTEM
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.
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.
Figure 2. Summary of Dip Switch Options.
DIFFERENTIALPRESSURESWITCH
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
attheburner'sauxiliarytube. Connectionscan 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.
This differential pressure switch is normally open and closes when
the combustion blower starts.
BLOCKEDFLUEPRESSURE 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.
FLAMESENSOR
The flame sensor acts to prove the flame has carried over from 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.
WATER FLOW SWITCH
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.
LIMIT CONTROLS
CAUTION
LIMIT CONTROLS ARE SAFETY DEVICES AND ARE NOT TO BE
USEDASATHERMOSTAT.
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.
If lockout occurs, manually push the ENTER/RESET
push-button on the display panel to restart the boiler.
ON/OFF SWITCH
The ON/OFF switch is a single-pole, single-throw rocker switch.
The switch provides 120VAC from the line source to the boiler.
COMBUSTIONAIR 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.
TANKPROBE
FORHOT WATER SUPPLYSYSTEMS (GWmodels),Atankprobeis
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).
FOR HOT WATER HEATING SYSTEMS (GB models) Due to the
many various types of systems and operating conditions, a tank
DIPSWITCH CONFIGURATION TABLE
SW1 OFF ON SELECTION:
A3 STAGE 4 STAGE EITHER 3OR 4STAGE SYSTEM
B3TRIALS 1TRIAL EITHER3OR1
CNOIRI IRI WHETHERSYSTEM ISIRIOR
GAS VALVE GAS VALVE STANDARD
DINLET TANK INLETORTANKAS
CONTROLLINGPROBE
ENOEXTERNAL EXTERNAL WHETHEREXTERNAL
THERMOSTAT THERMOSTAT THERMOSTATISUSED
FOUTLET210°F OUTLET240°F OUTLETMAXIMUMTEMPERATURE
G190°F 220°F MAX.SET-POINTTEMPERATURE
HDEGREES°F DEGREES°C EITHER°FOR°CFORDISPLAYED
TEMPERATURE

6
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.
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
The pump flow rate should not exceed the maximum
recommended flow rate, see table 4.
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.
FORHOT WATER HEATINGSYSTEMS (GBmodels or GWmodels
ordered without circulator), the circulator is NOT provided and
must be field-installed.
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.
Alowwatercutoffdeviceof the float type should be flushed every six
months.
DRAIN VALVE (Not Supplied)
Additional drain valves must be obtained and installed on each
boiler and tank for draining purposes.
SAFETYRELIEF VALVES
Your local code authority may have other specific relief valve
requirements not covered below.
WARNING
THE PURPOSE OF A SAFETY RELIEF VALVE IS TO AVOID
EXCESSIVEPRESSURE WHICH MAYCAUSE TANK EXPLOSION,
SYSTEMOR BOILERDAMAGE.
TOAVOIDWATERDAMAGEADRAINLINEMUSTBECONNECTED
TOASAFETYRELIEFVALVETODIRECTDISCHARGETOASAFE
LOCATION. ADRAIN LINE MUST NOT BE REDUCED FROMTHE
SIZE OF THE VALVE OUTLETAND IT MUST NOT CONTAINANY
VALVESBETWEENTHE BOILERANDTHE RELIEFVALVEORTHE
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
CREATEANUNSAFE CONDITION. INSTALLADRAINLINEWITH
A DOWNWARD SLOPE SUCH THAT IT NATURALLY DRAINS
ITSELF.
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.
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.
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.
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.
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.
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.
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.
INSTALLATIONINSTRUCTIONS
REQUIREDABILITY
INSTALLATIONOR SERVICEOFTHISBOILER REQUIRESABILITY
EQUIVALENT TO THAT OF A LICENSED TRADESMAN IN THE
FIELD INVOLVED. PLUMBING, AIR SUPPLY, VENTING, GAS
SUPPLY AND ELECTRICAL WORKARE REQUIRED.
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.)

7
•THE BOILER MUST NOT BE INSTALLED ON CARPETING.
•THEBOILERSHOULDNOTBE LOCATEDINANAREAWHERE
IT WILL BE SUBJECT TO FREEZING.
•THE BOILER SHOULD BE LOCATED NEAR AFLOOR DRAIN.
•THE BOILER SHOULD BE LOCATED IN AN AREA WHERE
LEAKAGE FROM THE BOILER OR CONNECTIONS WILL NOT
RESULTIN DAMAGETOTHEADJACENTAREAORTOLOWER
FLOORS OF THE STRUCTURE.
WHEN SUCH LOCATIONS CANNOT BE AVOIDED, A SUITABLE
DRAINPAN SHOULD BE INSTALLED UNDERTHEBOILER. Such
pans should be fabricated with sides at least 2-1/2" (6.5 cm) deep,
withlengthandwidthat 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.
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 ORREPAIRED. FLAMMABLEVAPORSARE
HEAVYAND TRAVELALONG THE FLOORAND MAY BE IGNITED
BYTHEIGNITER OR MAIN BURNER FLAMES CAUSING FIREOR
EXPLOSION.SOME LOCALCODESPERMITOPERATIONOFGAS
APPLIANCES IF INSTALLED 18 INCHES (46.0 CM) OR MORE
ABOVETHEFLOOR. THISMAYREDUCETHERISK IF LOCATION
IN SUCHANAREACANNOT BEAVOIDED.
FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY
OTHERPOTENTIAL FIRE HAZARDOUSARTICLESMUSTNEVER
BE PLACED ON OR ADJACENT TO THE BOILER.
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
UNDERNO CIRCUMSTANCESSHOULDTHEEQUIPMENTROOM
WHERETHE BOILER IS INSTALLEDEVERBE UNDER NEGATIVE
PRESSURE. PARTICULAR CARE MUST BE TAKEN WHEN
EXHAUSTFANS,COMPRESSORS,AIR HANDLING EQUIPMENT,
ETC., MAY INTERFERE WITH THE COMBUSTION AND
VENTILATIONAIR SUPPLIES OFTHISBOILER.
CHEMICALVAPORCORROSION
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.
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.
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.
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.
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.
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.
MODEL COMBUSTIBLEFLOOR KITNO.
(GB/GW)-1000 211093
(GB/GW)-1300 211093-1
(GB/GW)-1500 211093-2
(GB/GW)-1850 211093-3
(GB/GW)-2100 211093-4
(GB/GW)-2500 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.
AIRREQUIREMENTS
WARNING
FOR SAFE OPERATION, AN AMPLE SUPPLY OF AIR MUST BE

8
PROVIDED FOR PROPER COMBUSTION AND VENTILATION IN
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,
LUMINOUSBURNER FLAME,CARBONINGORSOOTING OFTHE
FINNED HEAT EXCHANGER, OR CREATE A RISK OF
ASPHYXIATION. DO NOT OBSTRUCT THE FLOW OF
COMBUSTIONANDVENTILATIONAIR.
UNCONFINEDSPACE
In buildings of conventional frame, brick or stone construction,
unconfined spaces may provide adequate air for combustion.
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.
CONFINEDSPACE
(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
WITHIN12INCHES OF THE ENCLOSURE TOP AND ONEWITHIN
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.
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.
(b) CANADIANINSTALLATIONS
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).
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.
Where power vented equipment is used in the same room as the
boiler, sufficient air openings must be supplied. UNDERSIZED
OPENINGS MAY RESULT IN INSUFFICIENT AIR FOR
COMBUSTION.
Where an exhaust fan is installed in the same room with a boiler,
sufficient openings for air must be provided in the walls.
UNDERSIZEDOPENINGSWILLCAUSE AIR TO BE DRAWN INTO
THE ROOM THROUGH THE CHIMNEY, CAUSING POOR
COMBUSTION. SOOTING MAY RESULT WITH AN INCREASED
RISKOFASPHYXIATION.
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.
TABLE6: DIRECTVENT KITS
Horiz. or Horiz. Direct Vent Kit No. Model Number
211090 G(W,B) 1000
211090-1 G(W,B) 1300
211090-1 G(W,B) 1500
211090-4 G(W,B) 1850
211090-2 G(W,B) 2100
211090-3 G(W,B) 2500
Vertical Direct Vent Kit No. Model Number
211089 G(W,B) 1000
211089-1 G(W,B) 1300
211089-1 G(W,B) 1500
211089-4 G(W,B) 1850
211089-2 G(W,B) 2100
211089-3 G(W,B) 2500
CAUTION
WHEN VENTING THE GENESIS BOILER THROUGH AN
OVERSIZED CHIMNEY (INCLUDING MASONRY CHIMNEYS),
ADDITIONALCAREMUST BE EXERCISED TOASSUREPROPER
DRAFT. FORPROPER OPERATION,AMINIMUMDRAFTOF -0.02"
W.C.ANDAMAXIMUMDRAFTOF-0.04"W.C.MUSTBEMAINTAINED.
ININSTANCESOF EXCESSIVEDRAFT,ABAROMETRICDAMPER
MAY BE REQUIRED TO ASSIST IN MAINTAINING THE PROPER
DRAFT. DRAFT SHOULD BE MEASURED 2 FEET (0.6 M)ABOVE
THE BOILER VENT COLLAR.
WARNING
THEINSTRUCTIONSINTHISSECTIONON VENTINGTHE BOILER
MUST BE FOLLOWED TO AVOID CHOKED COMBUSTION OR
RECIRCULATION OFFLUEGASES. SUCHCONDITIONSCAUSE
SOOTINGORRISKS OF FIREANDASPHYXIATION.
CONNECTINGBOILERTOACOMMONVENT
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.
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.
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.

9
1. Seal any unused opening in the common venting system.
2. Visuallyinspecttheventingsystemforpropersizeandhorizontal
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.
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,
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.
LOCATIONREQUIREMENTS(INTAKE/EXHAUST)
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.
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.
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

10
STANDARD VENT - VERTICAL (CATEGORY I)
IMPORTANT!
VENTPRESSURE MUSTBEMAINTAINED
BETWEEN -0.02" W.C. AND -0.04" W.C.AT 24"
(61.0cm) ABOVE BOILERCOLLAR.
•Connection for theapplianceexhaust vent tothe stack mustbe as directas possible. Maximum and minimumventing 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 InstallationCode(Canada).
•The horizontal breachingof avent must havean upwardslope of notless than 1/4inch perlinear foot (2cm/m) fromthe boiler
tothevent terminal. Thehorizontal portionofthe ventshallbe supportedtomaintain clearancesand topreventphysical damage
orseparation of joints.
TABLE7. STANDARDVERTICALVENTING (CATEGORYI)
* Extending venting over 70 feet (21.3 m) may require special considerations.
APPLIANCE CERTIFIED EXHAUST MAXIMUM LENGTH WITHOUT
MODEL CATEGORY VENTING VENT SIZE BAROMETRICDAMPER(FEET)
MATERIAL (INCHES)
TYPEB OR 10”(25.4 cm) 35 Feet (10.7 m) without damper
EQUIVALENT *70 Feet (21.3 m) max. with damper
1300 TYPEB OR 35 Feet (10.7 m) without damper
1500 EQUIVALENT 12" (30.5 cm) *70 Feet (21.3 m) max. with damper
1850 TYPEB OR 14"(35.6cm) 35 Feet (10.7 m) without damper
2100 EQUIVALENT *70 Feet (21.3 m) max. with damper
TYPE B OR 16" (40.6 cm) 35 Feet (10.7 m) without damper
EQUIVALENT *70 Feet (21.3 m) max. with damper
I
I
I
I
I000
2500
Figure 5.

11
TABLE 8. STANDARD HORIZONTALVENTING(CATEGORYIII)
STANDARD VENT - HORIZONTAL (CATEGORY III)
WARNING: No substitutions of flue pipe or vent cap material are allowed. Such substitutions would jeopardize the
safety and health of inhabitants.
•Amaximum of two elbows can be used on inlet and outlet vent piping respectively. Each elbow is equal to 10 feet (3 m) of
straightpipe.
• 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: [phone] or
Fax:[phone]. Pipe joints mustbe positively sealed.
APPLIANCE CERTIFIED EXHAUST MAXIMUM
MODEL CATEGORY VENTING VENT SIZE VENTLENGTH
MATERIAL (INCHES) (FEET)
STAINLESS
STEEL
1300 STAINLESS
1500 STEEL
1850 STAINLESS
2100 STEEL
STAINLESS
STEEL
III
III
III
III
I000
2500
10”(25.4 cm)
12" (30.5 cm)
14"(35.6cm)
16" (40.6 cm)
70' (21.3 m)
70' (21.3 m)
70' (21.3 m)
70' (21.3 m)
Figure 6.

12
DIRECT VENT - VERTICAL (CATEGORY I)
TABLE 9. DIRECTVENT (VERTICALEXHAUSTCONFIGURATIONS)
•Connection for theapplianceexhaust vent tothe stack mustbe as directas possible. Maximum and minimumventing 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 InstallationCode(Canada).
•Thevent shouldbe installedsoas toprevent theaccumulation ofcondensate and,where necessary,have meansprovided for
drainageof condensate. The horizontalbreaching of avent musthave an upwardslope of notless than 1/4inch perlinear foot
(2cm/m) fromthe boilerto thevent terminal. Thehorizontal portionof thevent shallbesupported tomaintain clearancesand to
preventphysical damageor separationofjoints.
Figure 7.
APPLIANCE CERTIFIED EXHAUSTVENT MAXIMUM AIRINTAKE AIRINLET MAXIMUM
MODEL CATEGORY EXHAUSTVENT SIZE(INCHES) EXHAUST VENT MATERIAL SIZE(INCHES) AIRINTAKE
MATERIAL LENGTH(FEET) LENGTH(FEET)
GAL.STEEL
I PVC,ABS OR
CPVC
GAL.STEEL
I PVC,ABS CR
CPVC
GAL.STEEL
I PVC,ABS OR
CPVC
GAL.STEEL
I PVC,ABS OR
CPVC
GAL.STEEL
I PVC,ABS OR
CPVC
I000
1300
1500
1850
2100
2500
TYPEBOR
EQUIVALENT
TYPEBOR
EQUIVALENT
TYPEBOR
EQUIVALENT
TYPEBOR
EQUIVALENT
TYPEBOR
EQUIVALENT
10"
(25.4 cm)
12"
(30.5 cm)
14"
(35.6 cm)
14"
(35.6 cm)
16"
(40.6 cm)
35'
(10.7 m)
35'
(10.7 m)
20'
(6.1 m)
20'
(6.1 m)
20'
(6.1 m)
35'
(10.7 m)
35'
(10.7 m)
20'
(6.1 m)
20'
(6.1 m)
20'
(6.1 m)
8"
(20.3 cm)
10"
(25.4 cm)
10"
(25.4 cm)
12"
(30.5 cm)
12"
(30.5 cm)

13
DIRECT VENT - HORIZONTAL (CATEGORY III)
WARNING: No substitutions of flue pipe or vent cap material are allowed. Such substitutions would jeopardize the
safety and health of inhabitants.
•Amaximum of two elbows can be used on inlet and outlet vent piping respectively. Each elbow is equal to 10 feet (3 m) of
straightpipe.
•Use onlyspecial gasvent pipes listedfor usewith CategoryIII gasburning heaters,such as stainlesssteel Saf-T-Ventby Heat
Fab, Inc. Inc., available from A.O. Smith WPC, 5621 W. 115th Street, Alsip, IL 60803 Phone: [phone] or
Fax:[phone]. Pipe joints mustbe positively sealed.
TABLE 10. DIRECT VENT(HORIZONTALEXHAUST CONFIGURATIONS)
Figure 8.
APPLIANCE CERTIFIED VENT MAXIMUM AIRINTAKE AIRINLET MAXIMUM
MODEL CATEGORY EXHAUST VENT SIZE VENTLENGTH MATERIAL SIZE AIRINTAKE
MATERIAL (INCHES) (FEET) (INCHES) LENGTH(FEET)
GAL.STEEL
III PVC, ABSOR
CPVC
GAL.STEEL
III PVC,ABSCR
CPVC
GAL.STEEL
III PVC, ABSOR
CPVC
GAL.STEEL
III PVC, ABSOR
CPVC
GAL.STEEL
III PVC, ABSOR
CPVC
I000
1300
1500
1850
2100
2500
STAINLESS
(SEALED)
STAINLESS
(SEALED)
STAINLESS
(SEALED)
STAINLESS
(SEALED)
STAINLESS
(SEALED)
10"
(25.4 cm)
12"
(30.5 cm)
14"
(35.6 cm)
14"
(35.6 cm)
16"
(40.6 cm)
35'
(10.7 m)
35'
(10.7 m)
20'
(6.1 m)
20'
(6.1 m)
20'
(6.1 m)
35'
(10.7 m)
35'
(10.7 m)
20'
(6.1 m)
20'
(6.1 m)
20'
(6.1 m)
8"
(20.3 cm)
10"
(25.4 cm)
10"
(25.4 cm)
12"
(30.5 cm)
12"
(30.5 cm)

14
STANDARD(VERTICAL)VENTING,CATEGORYI
THIS BOILER MAY BE VENTEDACCORDING 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 NATIONALFUELGAS CODE VENTTABLES.* 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 MUSTBE FOLLOWED.
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 LATESTADDENDA).*
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.
STANDARD(HORIZONTAL)VENTING,CATEGORYIII
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/provincialregulations 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.
For Category III installations, It is important that the Installed vent
be airtight. Please insure that all joints are sealed properly during
installation.
DIRECTVENTVERTICALANDHORIZONTALVENTING
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.
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.
HORIZONTALVENT INSTALLATION
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.
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.
Figure 9. Switching from Vertical to Horizontal Venting
Table11: VENT CONNECTION
VENTCONNECTOR MODELNUMBER
G(W,B) 1000 10" (25.4 cm)
G(W,B) 1300 12" (30.5 cm)
G(W,B) 1500 12" (30.5 cm)
G(W,B) 1850 14" (35.6 cm)
G(W,B) 2100 14" (35.6 cm)
G(W,B) 2500 16" (40.6 cm)
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.

15
CONVENTIONALSPACE HEATING 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.
Refertotable 4 showing flow rate vs. pressure drop and temperature
rise.
Figure 10 shows a typical installation of the boiler.
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.
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
controlvalvesorotherautomaticmeanstopreventgravitycirculation
oftheboilerwater during the cooling cycle. It is highly recommended
that the piping be insulated.
INSTALLATIONASBOILER 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.
BYPASSBALANCING
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.
AIRSEPARATOR
An air separator as shown in the piping diagram is reccommended
especially for modern commercial hydronic systems.
VENTVALVES
It is recommended that automatic, loose key or screwdriver type
vent valves be installed at each convector or radiator.
SYSTEMHEADERS
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.
SYSTEMINSTALLATION
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
due to freezing is not covered by the warranty.
Good practice requires that all piping, etc., be properly supported.
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.
HYDRONICINSTALLATION
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).
Table 12: INSTALLATIONITEMS
NO. SUGGESTEDITEMSFORINSTALLATION
1. PAIR OF SHORTPIPE NIPPLES, PAIROFBOILER
LOOPTEESAND BALLVALVE 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
5. PRESSURE GAUGE
6. LOW WATER CUTOFF (If Required By Local Code.)
7. SAFETY FLOW SWITCH (Factory-Installed)
8. RELIEF VALVE (Factory-Installed)
9. BOILER INLET - OUTLET
10. SYSTEMSUPPLYTEMPERATURETHERMOMETER
11. DRAIN or BLOW-DOWNVALVE
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.
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.
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
MINIMUMPRESSURE OF15 PSI(100kPa)MUSTBEMAINTAINED
ON THE BOILER AT ALL TIMES to avoid potential damage to the
boiler that may not be covered by the warranty.

16
Figure 10. Single or Multiple Boiler Installation Diagram
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.
Manifold headers are recommended for split systems with or
without zone valves and also those installations with zone
circulators. Ifthesystemistobesplitatremotepoints,goodpractice
requires special attention be given to main pipe sizing to allow
balancing of water flow.
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.
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 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
preventgravitycirculationthroughtheboiler 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.
SPACEHEATINGAPPLICATIONS
Controlling of these systems is decided mainly by the type of
building system controlling that is desired. A single boiler
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
mainwatertemperature controller. Withoneortwoboilers,individual
control settings at progressive temperature may be used. For more
than two boilers, electronic sequencing controlling is
recommended.
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.
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.
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.
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.
Multiple boiler installations are especially adapted to the use of
outdoor reset for main water temperatures. This feature is not

17
mandatory but offers smooth, efficient operation of a modern
system.
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.
24 VAC System Controller (Optional)
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. A24 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.
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.
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.
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.
THEWATERHEATERSHOULD BELOCATEDINANAREAWHERE
THE GENERAL PUBLIC DOES NOT HAVE ACCESS TO SET
TEMPERATURES.
HOT WATER SUPPLY BOILER
INSTALLATION
WATERLINECONNECTIONS
Where excessive heat exchanger condensation exists due to
continued low inlet water temperatures (below 120oF), a bypass
balance loop must be installed (see figures 11 and 13).
HARDWATERCONDITIONS
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. Whenwatersofteningor water treatment is not practical,
a comparatively easy method of periodic lime removal from the unit
must be employed.
WARNING
LIME ACCUMULATION CAN REDUCE THE LIFE OF THE
EQUIPMENT, REDUCE EFFICIENCYANDWASTEFUEL. BOILER
FAILURE DUE TO LIME OR SCALE BUILDUP VOIDS THE
WARRANTY.
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.
TANK PROBE INSTALLATION PROCEDURE
Atank 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.
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
OutlettemperatureSet-Pointto 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.
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.
EXPANSIONTANK
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
closed system is very important and is directly related to the total
water volume of the system. Refer to ASME or other reliable
specifications for sizing.

18
ONE GENESIS (MODEL GW) HOT WATER SUPPLY BOILER WITH HORIZONTAL TANK
Figure 12. Tank probe installation.
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.
DANGER
TEMPERATURESETTINGSHOULDNOTEXCEED
SAFE USE TEMPERATURE AT FIXTURES.
SEE WATER TEMPERATURE CONTROL
WARNING ON PAGE 23. IF HIGHER PREHEAT
TEMPERATURESARENECESSARYTO OBTAIN
ADEQUATE BOOSTER OUTPUT, ADD AN
ANTI-SCALD VALVE FOR HOT WATER
SUPPLIED TO FIXTURES.
WARNING
THE WATER MANIFOLD IS NOT DESIGNED TO
SUPPORTTHEWEIGHTOFTHEWATERPIPING
SYSTEM. ASONALL BOILER INSTALLATIONS,
SPECIAL CARE MUST BE TAKEN TO ENSURE
PROPERSUPPORT.
Figure 11. Single boiler with horizontal tank.
IMPORTANT
SAFETY FLOW SWITCH PROTECTS THE
BOILER IN CASE OF WATER SERVICE
INTERRUPTION OR CIRCULATOR FAILURE.
•PIPE TO OPEN DRAIN
X FACTORY-INSTALLED ON UNIT
 SUPPLIED WITH UNIT
FIELD-INSTALLED
INSTALL THERMAL EXPANSION
TANK ON COLD WATER
SUPPLY LINE, IF CHECK VALVE
OR PRESSURE REDUCING
VALVE IS USED IN SUPPLY.
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).
MINIMUM
PIPESIZE
MODELS INCHES
GW-1000
THRU 2 1/2"
2500 NPT
FACTORY PUMP SIZING
BASED ON 50 EQUIVALENT
FEET (15.2 m) OF PIPE.
MODELS
CIRCULATINGRETURN
LINECONNECTIONS
• TEMPERED WATER LOOP, IF USED,
CONNECTTOPOINTR.
• STOREDTEMPERATUREWATERLOOP,
IFUSED,CONNECTTOANYOPENING
NEARBOTTOMOFTANK.
TWOTEMPERATURE WATER
MIXING VALVE APPLICATION

19
ONE GENESIS (MODEL GW) HOT WATER SUPPLY BOILER WITH VERTICAL TANK
Figure 13. Single 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.
•PIPE TO OPEN DRAIN
X FACTORY INSTALLED ON UNIT
 SUPPLIED WITH UNIT
FIELD-INSTALLED
DANGER
TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE
TEMPERATUREAT FIXTURES. SEE WATER TEMPERATURE
CONTROLWARNINGON PAGE 23. IFHIGHERPREHEATTEM-
PERATURES ARE NECESSARY TO OBTAIN ADEQUATE
BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT
WATERSUPPLIED TOFIXTURES.
INSTALL THERMAL EXPANSION
TANK ON COLD WATER SUPPLY
LINE, IF CHECK VALVE OR
PRESSURE REDUCING VALVE
IS USED IN SUPPLY.
FACTORY PUMP SIZING BASED
ON 50 EQUIVALENT FEET
(15.2 m) OF PIPE.
MINIMUM
PIPESIZE
MODELS INCHES
GW-1000
THRU 2 1/2"
2500 NPT
MODELS
CIRCULATINGRETURN
LINECONNECTIONS
• TEMPERED WATER LOOP, IF USED,
CONNECTTOPOINTR.
• STOREDTEMPERATUREWATERLOOP,
IFUSED,CONNECTTOANYOPENING
NEARBOTTOMOFTANK.
TWOTEMPERATURE WATER
MIXING VALVE APPLICATION

20
Table 13. Suggested Pipe Size For Multiple Gas Appliances (Natural)
Table 14. Suggested Pipe Size For Multiple Gas Appliances (Propane Gas)
Length of Pipe in Feet (Metres)
Maximum Capacity of Pipe in BTU/hr and kW for Gas Pressures of 14 in. W.C. (0.5 psi) or Less and a Pressure Drop of 0.5 in. W.C.
(based on 0.60 Specific Gravity Gas w/Heating Value of 1,000 BTU’s/Ft3)
Nominal
Iron Pipe
Size Cap. 10Ft. 20Ft. 30 Ft. 40 Ft. 50 Ft. 60 Ft. 70Ft. 80Ft. 90 Ft. 100 Ft. 125 Ft. 150 Ft. 175 Ft. 200Ft.
(Inches) (3.05) (6.10) (9.14) (12.19) (15.24) (18.29) (21.34) (24.38) (27.43) (30.48) (38.10) (45.72) (53.34) (60.96)
11/4" BTU/hr 1,400,000 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
kW 410 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
11/2" BTU/hr 2,100,000 1,460,000 1,180,000 990,000 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
kW 615 428 346 290 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2" BTU/hr 3,950,000 2,750,000 2,200,000 1,900,000 1,680,000 1,520,000 1,400,000 1,300,000 1,220,000 1,150,000 1,020,000 - - - - - - - - -
kW 1,157 805 644 556 492 445 410 381 357 337 299 - - - - - - - - -
21/2" BTU/hr 6,300,000 4,350,000 3,520,000 3,000,000 2,650,000 2,400,000 2,250,000 2,050,000 1,950,000 1,850,000 1,650,000 1,500,000 1,370,000 1,280,000
kW 1,845 1,274 1,031 879 776 703 659 600 571 542 483 439 401 375
3" BTU/hr 11,000,000 7,700,000 6,250,000 5,300,000 4,750,000 4,300,000 3,900,000 3,700,000 3,450,000 3,250,000 2,950,000 2,650,000 2,450,000 2,280,000
kW 3,222 2,255 1,830 1,552 1,391 1,259 1,142 1,084 1,010 952 864 776 718 668
4" BTU/hr 23,000,000 15,800,000 12,800,000 10,900,000 9,700,000 8,800,000 8,100,000 7,500,000 7,200,000 6,700,000 6,000,000 5,500,000 5,000,000 4,600,000
kW 6,736 4,627 3,749 3,192 2,841 2,577 2,372 2,197 2,109 1,962 1,757 1,611 1,464 1,347
Length of Pipe in Feet (Metres)
Nominal
Iron Pipe
Size Cap. 10Ft. 20Ft. 30Ft. 40Ft. 50Ft. 60Ft. 70Ft. 80Ft. 90Ft. 100Ft. 125Ft. 150Ft. 175 Ft. 200Ft.
(Inches) (3.05) (6.10) (9.14) (12.19) (15.24) (18.29) (21.34) (24.38) (27.43) (30.48) (38.10) (45.72) (53.34) (60.96)
1" BTU/hr 1,060,800 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
kW 311 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
11/4" BTU/hr 2,184,000 1,482,000 1,201,200 1,029,600 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
kW 640 434 352 302 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
11/2" BTU/hr 3,276,000 2,277,600 1,840,800 1,544,400 1,404,000 1,263,600 1,170,000 1,076,400 1,014,000 - - - - - - - - - - - - - - -
kW 959 667 539 452 411 370 343 315 297 - - - - - - - - - - - - - - -
2" BTU/hr 6,162,000 4,290,000 3,432,000 2,964,000 2,620,800 2,371,200 2,184,000 2,028,000 1,903,200 1,794,000 1,591,200 1,482,000 1,326,000 1,248,000
kW 1,805 1,256 1,005 868 768 694 640 594 557 525 466 434 388 366
21/2" BTU/hr 9,828,000 6,786,000 5,491,200 4,680,000 4,134,000 3,744,000 3,510,000 3,198,000 3,042,000 2,886,000 2,574,000 2,340,000 2,137,200 1,999,800
kW 2,878 1,987 1,608 1,371 1,211 1,097 1,028 937 891 845 754 685 626 585
3" BTU/hr 17,160,000 12,012,000 9,750,000 8,268,000 7,410,000 6,708,000 6,084,000 5,772,000 5,382,000 5,070,000 4,602,000 4,134,000 3,822,000 3,556,800
kW 5,026 3,518 2,856 2,421 2,170 1,965 1,782 1,690 1,576 1,485 1,348 1,211 1,119 1,042
4" BTU/hr 35,880,000 24,648,000 19,968,000 17,004,000 15,132,000 13,728,000 12,636,000 11,700,000 11,232,000 10,452,000 9,360,000 8,580,000 7,800,000 7,176,000
kW 10,508 7,219 5,848 4,980 4,432 4,021 3,701 3,427 3,290 3,061 2,741 2,513 2,284 2,102
Maximum Capacity of Pipe in BTU/hr and kW for Gas Pressures of 14 in. W.C. (0.5 psi) or Less and a Pressure Drop of 0.5 in. W.C.
(based on 1.53 Specific Gravity Gas w/Heating Value of 2,500 BTU’s/Ft3)