A. O. Smith HW-670 User Manual

BURKAY® HOT WATER

Hot Water Supply Boiler

SUPPLY BOILER

FEATURES

ALL NON-FERROUS WATERWAYS

■ All castings are made of Bronze or Brass

■ All water tubes are made from copper

■ Brazed joints or flare union construction make the boiler immune to the effects of

thermal shock and thermal cycling

■ A great boiler for domestic hot water supply

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 surrounds the main burner and captures the

radiant heat

■ A wrap of insulation on the outside of the coil retains the heat captured by the

circulating water

COPPER HEAT EXCHANGER

■ Directly above the coil and the main burner is a compact, horizontal, copper

fin tube heat exchanger

■ The flue gases must pass through this efficient heat exchanger before leaving

the boiler

■ This unique Burkay coil and heat exchanger design provide maximum heat

transfer and proven field durability

BURKAY® BURNER MAXIMIZES EFFICIENCY

■ The patented Burkay burner uses primary air injection at up to 72 individual orifices

plus secondary entrainment of air

■ Approved for installation on combustible floors as shipped from factory.

HW-300

through

HW-670

HW - INDOOR INSTALLATION ONLY

GAS VALVES

■ Slow opening redundant gas valves ensure smooth light-off without flame roll-out

or pilot outage

THERMAL BALANCER

■ Patented pump delay system that allows boiler and pump to run simultaneously but

delays pump shut off at end of heating cycle to remove usable heat from the heat
exchanger and reduce the scale forming tendencies of motionless hot water

AUTOMATIC SAFETY CONTROLS AND ELECTRONIC IGNITION

■ Proven pilot ignition system provides flame failure response in under one (1) second

■ Redundant high limit controls and gas valves assure safe shutoff in the event of

overheating or flame failure

■ Requires 120V 60Hz, maximum inlet gas pressure of 14” WC and activation of boiler by

external temperature control

WORKING PRESSURE

■ ASME approved, hydrostatically tested and certified for 160 psi

■ Ships with ASME 125 psi relief valve

COMPLIANCE

■ These models meet the thermal efficiency and standby loss requirements of the U.S.

Department of Energy and current edition ASHRAE/IESNA 90.1.

LIMITED WARRANTY OUTLINE

■ Consult written warranty or contact your A. O. Smith sales representative

A. O. Smith Corporation • 500 Tennessee Waltz Parkway • Ashland City, TN 37015 • 800-527-1953 Toll-free USA

www.hotwater.com

Page 1 of 2

Revised September 2014 AOSDG25600

TABLE 1. DIMENSIONS AND CAPACITY DATA

FIGURE 1. DIMENSIONS

FIGURE 1. DIMENSIONS

LOCATION OF MANUAL
MAIN SHUTOFF VALVE
OUTSIDE JACKET WHEN
CODE REQUIRE
(NOT SUPPLIED)

Hot Water Supply Boiler

DIMENSIONS IN INCHES

Overall height 65 (1651) 57-1/8 (1451) 57-1/8 (1451) 68-5/16 (1735) 68-5/16 (1735)

A

Height to Top of Jacket 43-1/4 (1099) 45-1/8 (1146) 45-1/8 (1146) 56-1/4 (1429) 56-1/4 (1429)

B

Floor to Center Line Water Outlet 36 (914) 38-3/4 (984) 38-3/4 (984) 46 (1168) 46 (1168)

C

Diameter of Jacket 25-1/4 (641) 27 (686) 27 (686) 27 (686) 27 (686)

D

Floor to Center Line Water Inlet 12 (305) 12 (305) 12 (305) 1 2 (305) 12 (305)

E

Draft Diverter Outlet Diameter 8 (203) 10 (254) 10 (254) 10 (254) 12 (305)

F

Floor to Center Line Gas Inlet 16-1/2 (419) 16-3/4 (425) 16-3/4 (425) 8 (457) 18 (457)

G

Overall Depth 29-5/8 (753) 31-1/2 (800) 31-1/2 (800) 36-1/2 (927) 36-1/2 (927)

H

Support Height 9 (229) 9 (229) 9 (229) 9 (229) 9 (229)

J

Width of Control String (approx.) 14 (356) 14 (356) 14 (356) 11 (279) 11 (279)

K

Pipe Size of Water Inlet (NPT) 1-1/4 1-1/2 1-1/2 2 2

L

Pipe Size of Water Outlet (NPT) 1-1/4 1-1/2 1-1/2 2 2

M

Pipe Size of Gas Inlet (NPT) 3/4 3/4 1 1 1

N

Control String Plus 1/2 Jacket Diameter (approx.) 26-5/8 (676) 27-1/2 (699) 27-1/2 (699) 24-1/2 (622) 24-1/2 (622)

P

Horizontal Length between Water Inlet & Outlet 5-3/8 (137) 5-1/2 (140) 5-1/2 (140) 5-3/4 (146) 5-3/4 (146)

S

Control String from Jacket 5 (127) 5 (127) 5 (127) 7 (178) 7 (178)

T

Approximate shipping weight lbs. (Kilograms) 250 (113) 301 (137) 301 (137) 381 (173) 381 (173)

NOTE: All dimensions in inches (millimeters) except pipe size which is NPT

TABLE 2. FLOW, HEAD AND TEMPERATURE RISE

MODELS

HW 300 300,000 240,000 24 8 16 3 12 2
HW 399 399,000 319,200 32 16 21 7 16 5
HW 420 420,000 336,000 34 18 22 8 21 5.5
HW 520 520,000 416,000 42 12 28 5 26 4

HW 670 Nat 660,000 528,000 53 22 35 10 26 5.5

HW 670 Prop 670,000 536,000 54 22 36 10 27 5.5

NATURAL & PROPANE (LP) GAS

BTU INPUT/OUTPUT

INPUT RATING BTU/HR

MODELS

HW-300 HW-399 HW-420 HW-520 HW-670

TEMPERATURE RISE AND PRESSURE DROP

OUTPUT RATING BTU/HR

NATURAL & PROPANE (LP) GAS

20°F RISE 30°F RISE 40°F RISE

GPM

PD-FT
HEAD

GPM

PD-FT
HEAD

GPM

PD-FT
HEAD

EXTRA OPENING
FOR THERMOMETER
AND PRESSURE
RELIEF VALVE
HW-520 AND
HW-670

TABLE 3. RECOVERY CAPACITIES

MODELS TYPE OF GAS

HW 300

HW 399

HW 420

HW 520

HW 670 Natural 660,000 193

HW 670 Propane 670,000 196

Hot Water Supply Boiler for domestic hot water purposes shall be Model(s) No. __________________ as manufactured by A. O. Smith or an approved equal. Boiler(s)
shall be gas-fired, and design certified by an ANSI approved/accredited independent rating laboratory, capable of supplying _____ gph at 100°F temperature
rise equipped to burn __________ gas, with input rating of _____ BTU/hr. and bearing the ASME code symbol. Boiler(s) shall be up flow type having all non­ferrous waterways, and employing a copper finned heat exchanger and a tightly wound copper coil combustion chamber with 160 psi working pressure rating.
Boiler(s) shall be equipped with an electric gas valve 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 flame 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 certified draft diverter and a fully illustrated instruction manual. Certified for installation
on combustible flooring. Outer jacket shall be of baked enamel finish. The coil, heat exchanger and burner shall have a five 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.

A. O. Smith Corporation • 500 Tennessee Waltz Parkway • Ashland City, TN 37015 • 800-527-1953 Toll-free USA

www.hotwater.com Revised September 2014

INPUT °F 20 40 50 60 70 80

BTU/HR kW °C (11) (22) (28) (33) (39) (44)

Natural

Propane LPH 5,506 2,753 2,202 1,835 1,573 1,377

Natural

Propane LPH 7,323 3,662 2,929 2,441 2,092 1,831

Natural

Propane LPH 7,708 3,854 3,083 2,569 2,202 1,927

Natural

Propane LPH 9,544 4,772 3,818 3,181 2,727 2,386

300,000 88

399,000 117

420,000 123

520,000 152

GPH 1,455 727 582 485 416 364

GPH 1,935 967 774 645 553 484

GPH 2,036 1,018 815 679 582 509

GPH 2,521 1,261 1,008 840 720 630

GPH 3,200 1,600 1,280 1,067 914 800

LPH 12,113 6,057 4,845 4,038 3,461 3,028

GPH 3,248 1,624 1,299 1,083 928 812

LPH 12,297 6,148 4,919 4,099 3,513 3,074

Suggested Specification

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