A.O. Smith QOS1221 Specifications
®
Hydronic Heating Boilers
ALL NON-FERROUS WATERWAYS
All castings are made of Bronze or Brass. All water tubes are made from copper. Brazed joints or
fl are union construction make the heater immune to the effects of thermal shock and thermal cycling.
The Burkay
applications.
EFFICIENT COPPER COIL COMBUSTION CHAMBER
The combustion chamber is a heat exchanger formed from a two passage coil of tightly wound
continuous copper tube. Water circulating through this coil captures radiant heat. A wrap of
insulation on the outside of the coil retains the heat captured by the circulating water.
Up to 82% effi cient
COPPER HEAT EXCHANGER
Directly above the coil and the main burner is a compact, horizontal, copper fi n tube heat exchanger.
The fl ue gases must pass through this effi cient heat exchanger before leaving the boiler. This unique
Burkay coil and heat exchanger design provide maximum heat transfer and proven fi eld durability.
MODELS MEET OR EXCEED THE THERMAL EFFICIENCY AND STANDBY LOSS
REQUIREMENTS OF THE U. S. DEPARTMENT OF ENERGY AND CURRENT
EDITION OF ASHRAE/IESNA 90.1
BURKAY BURNER MAXIMIZES EFFICIENCY
The patented Burkay® burner uses primary air injection at up to 72 individual orifi ces plus secondary
entrainment of air.
GAS VALVES
Step opening or slow opening redundant gas valves ensure smooth light-off without fl ame roll-out or
pilot outage.
®
boiler provides one of the smallest foot prints in the industry. Ideal for multiple boiler
HW-300 THRU
HW-670
THERMAL BALANCER
Factory supplied for use with primary secondary heating systems. Cycles the secondary pump with the
burner, but delays pump shut off at the end of the heating cycle to remove usable heat from the
boiler. Virtually eliminates stand-by heat losses at the boiler.
AUTOMATIC SAFETY CONTROLS AND ELECTRONIC IGNITION
Proven pilot ignition system provides fl ame failure response in under one (1) second. Redundant high
limit controls and gas valves assure safe shut off in the event of overheating or fl ame failure. Requires
120V 60Hz. Maximum inlet gas pressure 14” W.C. Minimum gas pressure 4.5” W.C. Requires remote
temperature system control: loop stat, energy management system, Indoor/ Outdoor Reset control.
(Not furnished with the boiler.)
WORKING PRESSURE
ASME approved, hydrostatically tested and certifi ed for 160 psi. Supplied with ASME relief valve 50#.
OPTIONAL EQUIPMENT
CSD-1 code, California code, New York code, Low Water Cutoff, Indoor/Outdoor Reset and Sequencing
Panel (1-8 Boilers).
LIMITED WARRANTY OUTLINE
If the coil, heat exchanger or burner should fail within 10 years, under the terms of the warranty;
A. O. Smith will furnish a replacement part; installation, labor, handling and local delivery extra. When
used for hot water supply or swimming pool application, the coil, heat exchanger and burner warranty
is 5 years. This outline is not a warranty. For complete information, consult the written warranty or
A. O. Smith Water Products Company.
Not approved for instantaneous applications.
June 2010R
Revised March 2010
Page 1 of 2
AOSHG30500
®
Hydronic Heating Boilers
HW670
NATURAL GAS
HW670 ONLY
ONLY
Approx.
Approx.
Approx.
Ship. Wt.
Ship. Wt.
Models A B C D E F G H J K L M N P Q R S T Lbs.
HW-300 65 43-1/4 36 25-1/4 12 8 16-1/2 29-5/8 9 14 1-1/4 1-1/4 3/4 26-5/8 1 10-1/8 5-3/8 5 240
HW-399 57-1/8 45-1/8 38-3/4 27 12 10 16-3/4 31-1/2 9 14 1-1/2 1-1/2 1 27-1/2 1 1 1-1/4 5-1/2 5 291
HW-420 57-1/8 45-1/8 38-3/4 27 12 10 16-3/4 31-1/2 9 14 1-1/2 1-1/2 1 27-1/2 1 1 1-1/4 5-1/2 5 291
HW-520 68-5/16 56-1/4 46 27 12 10 18 36-1/2 9 11 2 2 1 24-1/2 3-1/2 12 5-3/4 7 361
HW-670 67 56-1/4 46 27 12 12 18 36-1/2 9 11 2 2 1 24-1/2 3-1/2 12 5-3/4 7 361
HW-670 67 56-1/4 46 27 12 12 18 36-1/2 9 11 2 2 1 24-1/2 3-1/2 12 5-3/4 7 361
Models A B C D E F G H J K L M N
HW-300 65 43-1/4 36 25-1/4 12 8 16-1/2 29-5/8 9 14 1-1/4 1-1/4 3/4
HW-399 57-1/8 45-1/8 38-3/4 27 12 10 16-3/4 31-1/2 9 14 1-1/2 1-1/2 1
HW-420 57-1/8 45-1/8 38-3/4 27 12 10 16-3/4 31-1/2 9 14 1-1/2 1-1/2 1
HW-520 68-5/16 56-1/4 46 27 12 10 18 36-1/2 9 11 2 2 1
Prop.
Prop.
HW-670 67 56-1/4 46 27 12 12 18 36-1/2 9 11 2 2 1
Nat.
Models Nat ural & Propane (LP) Gas Natural & Propane (LP) Gas GPM Head GPM Head GPM Head
Nat.
HW-670 67 56-1/4 46 27 12 12 18 36-1/2 9 11 2 2 1
TtuptuO/tupnI UTB emperature Rise and Pressure Drop
20 Deg. F Rise 30 Deg. F Rise 40 Deg. F Rise
Input Rating BTU/Hr. Output Rating BTU/Hr. PD-Ft. PD-Ft. PD-Ft.
,443000,024 024-WH
554,635000,076PL 076-WH
NOTE: To compensate for the effects of high altitude areas above 2,000 feet, the input, output, and heating load ratings should
be reduced approximately 4% for each 1,000 feet above sea level.
QRSTLbs.
STLbs.
110-1/85-3/85240
5-3/8 5 240
11 1-1/4 5-1/2 5 291
5-1/2 5 291
11 1-1/4 5-1/2 5 291
5-1/2 5 291
3-1/2 12 5-3/4 7 361
5-3/4 7 361
3-1/2 12 5-3/4 7 361
5-3/4 7 361
3-1/2 12 5-3/4 7 361
5-3/4 7 361
Ship. Wt.
211351832002,742000,003 003-WH
5517026103097,223000,993 993-WH
5.5618128123004
4025422193000,924000,025 025-WH
5.55201432215000,345000,066.taN 076-WH
5.55201432245
SUGGESTED SPECIFICATIONS
The hydronic heating boiler(s) shall be an A. O. Smith Model HW _________ having an input rating of ________ BTU/hr., an output rating of ___________ BTU/hr., when fi red using Natural/Propane gas. The boiler(s) shall be design certifi ed
by an ANSI approved/accredited independent rating laboratory. The boiler shall bear the ASME “H” stamp and shall be National Board registered for 160 PSI working pressure. Boiler(s) shall be up fl ow type having all non-ferrous
waterways, and employing a copper fi nned heat exchanger and a tightly wound copper coil combustion chamber. Boiler(s) shall be equipped with an electric gas valv e of the step-opening type, an adjustable limit control which will break
the electric circuit on temperature rise, intermittent ignition with one (1) second shutdown in the event of pilot fl ame failure, a gas pressure regulator properly set for the gas to be supplied, and a coil limit switch for shut off in event of
excessive water temperature, a certifi ed draft diverter and a fully illustrated instruction manual. Certifi ed for combustible fl ooring. Outer jacket shall be of baked enamel fi nish. The coil, heat exchanger and burner shall have a ten year
limited warranty as outlined in the written warranty.
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.
June 2010R
Revised March 2010
www.hotwater.com
Page 2 of 2
AOHHG30500
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