Page 1
Commercial Gas Boilers
MODELS
84% EFFICIENT, LOW-NOx HOT WATER SUPPLY BOILERS
FEATURES
A. O. Smith Genesis® boilers offer everything you could ask for in a non-condensing boiler.
They provide the highest possible 84% thermal efficiency, outstanding venting flexibility,
space-saving stackable design and a new, advanced Energy Management Control (EMC) system.
Genesis models are available for installation indoors (GW Series) or outdoors (GWO Series).
NEW EMC-5000 ENERGY MANAGEMENT CONTROL
Patent pending
Controls every electrical boiler function, including pump operation and main burner ignition,
delivers precise temperature management, with ±1º accuracy
Display panel shows current operating status and fault readings in easy-to-understand
English instead of confusing numeric codes
Display also shows temperature setpoints, outlet temperature, current inlet/outlet
differential (
Help screens assist in boiler setup and explain control options
Included remote temperature sensor when mounted in the storage tank
allows the tank temperature to be set and monitored at the boiler
TWO-STAGE GAS FIRING SYSTEM
Twin gas valve firing system prevents short cycling and ensures
smooth operation, saves fuel and extends boiler life
T) and tank temperature
GW/GWO-300
THROUGH
GW/GWO-750
Prevents short cycling when demand is low, delivers maximum output when
demand is high
LOW-NOX OPERATION
Meets SCAQMD Rule 1146.2 air quality standards
COPPER FINNED-TUBE HEAT EXCHANGER
Designed for maximum durability and serviceability
Copper is lightweight for easier handling and immune to thermal shock
Removable headers allow easy inspection of waterways
SPACE-SAVING DESIGN
Smaller footprint versus other horizontal copper fin-tube boilers
Optional stack rack allows one unit to be stacked on top of another, doubling output within
the footprint of a single unit
MEETS ASHRAE/IESNA 90.1-2004
FIVE-YEAR HEAT EXCHANGER LIMITED WARRANTY
For complete information, consult written warranty
Revised October 2012
Revised November 2008
H
PG 1 OF 4
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Commercial Gas Boilers
GW SERIES INDOOR MODELS GWO SERIES OUTDOOR MODELS
MODEL
NUMBER
GW SERIES INDOOR MODELS
GW-300 300,000 5 5 1-1/2 3/4 29-1/2 14-13/16 9 12
GW-400 399,900 6 6 1-1/2 1 35-3/4 17-15/16 9 14-3/4
GW-500 500,000 66214221-1/16 9 14-3/4
GW-650 650,000 8 8 2 1-1/4 51-3/8 25-3/4 9 14-3/4
GW-750 750,000 8 8 2 1-1/4 57-3/8 28-7/8 9 17-1/4
GWO SERIES OUTDOOR MODELS
GW-300 300,000 - - 1-1/2 3/4 - 49 24-3/16 -
GW-400 400,900 - - 1-1/2 1 - 55-1/4 24-3/16 -
GW-500 500,000 - - 2 1 - 61-1/2 24-3/16 -
GW-650 650,000 - - 2 1-1/4 - 70-7/8 - 27-11/16
GW-750 750,000 - - 2 1-1/4 - 77-1/8 - 27-11/16
Revised October 2012
Revised November 2008 PG 2 OF 4
BTU INPUT
PER HOUR
EXHAUST VENT AIR INLET WATER CONN. GAS PIPE
www.hotwater.com
DIMENSIONS IN INCHES
(SEE DRAWINGS ABOVE)
WIDTH A B C
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Commercial Gas Boilers
OTHER GENESIS®FEATURES
FACTORY-INSTALLED CIRCULATING PUMP
Pre-wired, integrally controlled by EMC-5000 control
Adjustable pump time delay allows removal of usable residual
heat during stand-by cycle, virtually eliminating stand-by heat loss
ASME PRESSURE RELIEF VALVE 125#
FACTORY INSTALLED FLOW SWITCH
ALTERNATE THERMOSTAT TERMINALS (24V)
MANUAL RESET HIGH LIMIT
BLOCKED FLUE SWITCH
BLOCKED INLET SWITCH
AIR PROVING SWITCH
GENESIS®OPTIONS
CSD-1 CODE
NEW YORK CODE
CALIFORNIA CODE
ALARM BELL
ALL-BRONZE CIRCULATING PUMP
HARD WATER PUMP
BRONZE HEADERS
STACK RACK
LOW WATER CUT-OFF
EXTENDED VENTING KIT
SEQUENCING CONTROL PANEL (FOR 2-8 BOILERS)
COMBUSTIBLE FLOOR SHIELD
DRY CONTACTS FOR ANY BOILER FAILURE
CUPRO-NICKEL HEAT EXCHANGER
CSA CERTIFIED VENT KIT
GENESIS®VENTING VERSATILITY
DIRECT-VENTING
SIDEWALL VENTING CONVENTIONAL VENTING
For the most current Genesis venting distances/information,
consult the Genesis Product Manual, available through your local
A. O. Smith representative, or online at www.hotwater.com.
MODEL
NUMBER
GW/GWO-300 300,000 761 609 507 435 380 338 304 277 254 234 217
GW/GWO-400 399,900 1014 811 676 580 507 451 406 369 338 312 290
GW/GWO-500 500,000 1268 1015 845 725 634 564 507 461 423 390 362
GW/GWO-650 650,000 1649 1319 1099 942 824 733 659 600 600 507 471
GW/GWO-750 750,000 1902 1522 1268 1087 951 845 761 692 634 585 544
Gas Supply Pressure: 13.8” W.C. maximum natural and propane; 4.5” W.C. minimum natural; 11.0” W.C. minimum propane.
Genesis boilers are approved for installation on noncombustible flooring in an alcove with minimum clearance to combustibles of:
3 inches sides, and back; 3 inches top, front alcove; 6 inches vent.
For installation on combustible flooring use the optional Combustible Floor Kit.
Genesis boilers must be connected to a single phase dedicated line source that is: 120 volts, 60 hertz and 20 amps.
Revised October 2012
Revised November 2008 PG 3 OF 4
BTU INPUT
PER HOUR
40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140°
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RECOVERY — GALLONS PER HOUR AT °F TEMPERATURE RISE
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Commercial Gas Boilers
SUGGESTED SPECIFICATION
The hot water supply boiler(s) shall be an A. O. Smith Genesis® Model GW ___________________ having an input rating of __________________ BTU/hr.
and capable of supplying no less than _________________GPH at a 100ºF temperature rise when fired with Natural/Propane gas. The boiler shall bear
the ASME “H” stamp and shall be National Board registered for 160 PSI working pressure. The boiler shall be test certified at 84% thermal efficiency
by CSA per ANSI Z21.13/CSA 4.9 Harmonized Standard Latest Addenda. The boiler’s copper fin tube heat exchanger shall be a horizontal, single row,
two pass design. The solid copper tubes shall have integral extruded copper fins spaced at “7” fins per inch, and be rolled into heavy steel tube sheets.
High temperature silicone “O” rings shall provide a watertight seal between each tube and the ASME code Bronze/Cast Iron headers. Headers must
be field removable to allow complete inspection of all waterways. Non-removable headers, with tubes rolled directly into the headers, shall not be
acceptable. The low mass, low water volume heat exchanger shall be explosion-proof and immune to thermal shock.
The combustion chamber shall be fully lined with high temperature ceramic fiber insulation, rated to 2,300°F. The jacket panels shall be coated with
a baked-on powder-coat finish, suitable for outdoor service. The jacket shall be of tight construction, and weather- and water-resistant.
The hot water supply boiler(s) shall be supplied with a factory supplied, sized and wired boiler-circulating pump.
The boiler shall employ a fan induced premixed multi-burner system firing into a pressurized combustion chamber. Atmospheric or power burners will
not be acceptable. Only stainless steel/titanium alloy burners will be acceptable. All boiler functions shall be controlled, operated, and monitored by
a microprocessor-based control. The microprocessor shall control the boiler temperature and be accurate to within plus or minus 1°F. The hot surface
ignition system shall employ a separate flame sensor for maximum reliability.
The boiler shall be supplied with a remote tank thermistor for sensing and controlling the hot water storage tank temperature up to 1,000 feet away.
Provisions for connecting a remote thermistor, alarm bell, pump, and alternate temperature controller must be provided.
Factory mounted and wired flow, blower prover, and blocked flue switches shall be provided. The gas train shall meet or exceed the requirements
of ANSI Z21.13 and include gas pressure regulator, manual gas cock, redundant safety gas valve, operating control valve, and plugged pressure test
tapings. The ASME rated pressure relief shall be factory installed.
The boiler shall be certified for direct horizontal through-the-wall venting, or direct vertical venting; in addition to sidewall or conventional vertical
venting. The boiler must be field convertible from top mounted venting to rear mounted venting. The boiler shall be capable of horizontal sidewall
or direct venting up to 35 equivalent feet without the aid of any optional sidewalll vent fans or blowers.
For Technical Information and Automated Fax Service, call 800-527-1953. A.O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Revised October 2012
Revised November 2008 PG 4 OF 4
www.hotwater.com
AOSDG25200
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