A O Smith NW 37 670 User Manual

DURA-POWER MODELS NW 37- 670

COMMERCIAL ELECTRIC WATER BOILERS

• Installation • Operation • Service • Maintenance • Limited Warranty

CAUTION

TEXT PRINTED OR OUTLINED IN RED CONTINS INFORMATION

RELATIVE TO YOUR SAFETY. PLEASE READ THOROUGHLY

BEFORE INSTALLING AND USING THE APPLIANCE.

STANDARD

FLOOD WARNING

IF THE BOILER SHOULD BECOME IMMERSED IN

WATER AT ANY TIME, THE BOILER SHOULD BE

A DIVISION OF A.O. SMITH CORPORATION

RENTON, WASHINGTON

EXAMINED BY A COMPETENT SERVICE PERSON

BEFORE IT IS RETURNED TO SERVICE.

www.hotwater.com

PLACE THESE INSTRUCTIONS ADJACENT TO THE BOILER AND NOTIFY OWNER TO KEEP FOR

FUTURE REFERENCE.BE SURE THAT THE WARRANTY INFORMATION

HAS BEEN FILLED IN ON COMPLETION OF INSTALLATION.

PRINTED IN U.S.A. 0004G 0900

PART NO. 60047-002 REV.2

SIZES AND DATA 780KW THRU 3300KW

Model Number

Inlet* &

Boiler

Prefix Gal.Cap. Std.KWInput

G**

Outlet*

Drain

1 1/2

220

334

400

500

780K

840K

900K

25 1/2

30 5 1/2

30 7 1/4

33 7 3/4

36 7 3/4

960K

1020K

1080K

1140K

1200K

1260K

1380K

1500K

1620K

1740K

1800K

1860K

1980K

2100K

2200K

2340K

90 1/2

25 1/2 2 1/2

26 1/2 2 1/2

500

2460K

90 1/2

26 1/2 2 1/2

36 7 3/4

500

670

2580K

2700K

2820K

2940K

3060K

3180K

3300K

90 1/2

96 1/2

26 1/2 2 1/2

30 1/2 2 1/2

36 7 3/4

39 7 3/4

NOTE: For boilers 3400KW to 6000KW, consult factory.

* All fittings under 4” will be threaded type. All fittings 4” and larger will be flanged.

** Where overall height is a problem a larger diameter vessel with a reduced height may be furnished.

ELECTRICAL/RECOVERY DATA

WATER BOILER SPECIFICATIONS

Model Number

Gal. Std. KW

BTU Output

Gal./Hr.

100°F Rise

180

Number of Number of

Standard Number

and KW of Steps

1@45

Amperage 3 Phase

208v 240V 480V 575V

Prefix

Cap.

Input

45K

60K

75K

90K

Elements

Steps

153,585

204,720

255,975

307,170

358,365

409,560

511,950

614,340

716,730

128

171

213

250

292

334

417

500

584

668

751

834

917

1001

1084

108

144

180

217

253

289

361

433

505

577

650

722

794

866

938

108

126

144

180

216

252

288

324

360

396

432

468

105

121

151

181

211

241

271

301

331

362

392

240

300

369

430

492

615

738

861

1@60

1@75

3@30

105K

120K

150K

180K

210K

240K

270K

300K

330K

360K

390K

420K

450K

480K

540K

600K

660K

720K

780K

840K

900K

960K

1020K

1080K

1140k

1200K

1260K

1380K

1500K

1620K

1740K

1800K

1860K

1980K

2100K

2200K

2340K

2460K

2580K

2700K

2820K

2940K

3@30+1@15

4@30

5@30

4@30+1@60

3@30+2@60

2@30+3@60

1@30+4@60

5@60

5@60+1@30

6@60

6@60+1@30

7@60

819,120

921,510

984

1107

1230

1353

1476

1599

1722

1845

1968

2214

2460

2706

2952

3198

3444

3690

3936

4182

4428

4674

4920

5166

5658

6150

6642

7134

7380

7626

8118

8610

9102

9594

10080

10578

11070

11562

12054

1,023,900

1,126,290

1,228,680

1,331,070

1,433,460

1,535,850

1,638,240

1,843,020

2,047,800

2,252,580

2,457,360

2,662,140

2,866,920

3,071,700

3,276,480

3,481,260

3,636,040

3,890,820

4,095,600

4,300,380

4,709,940

5,119,500

5,529,060

5,938,630

6,143,400

6,348,180

6,757,740

7,167,300

7,576,860

7,986,420

8,395,980

8,805,540

9,315,100

9,624,660

10,034,220

1168 1010

1251 1083

1334 1155

1501 1299

1668 1443

504

540

576

648

422

452

487

542

7@60+1@30

8@60

150

220

334

400

500

670

9@60

10@60

720

602

8@60+2@90

8@90

8@90+1@60

9@90+1@30

10@90

8@90+2@120

6@90+4@120

4@90+6@120

2@90+8@120

10@120

8@120+2@150

4@120+6@150

10@150

792

663

864

723

936

783

1008

1080

1152

1224

1296

1368

1440

1512

1656

1800

1944

2068

2160

2232

2376

2520

2664

2808

2952

3096

3240

3384

3528

843

904

964

1024

1084

1145

1205

1265

1386

1506

1627

1747

1807

1868

1988

2109

2229

2350

2470

2590

2711

2832

2952

100

108

116

120

124

132

140

148

156

164

172

180

188

196

6@90+9@120

2@90+13@120

15@120

13@120+2@150

9@120+6@150

5@120+10@150

1@120+14@150

18@120+2@90

18@120+2@150

14@120+6@150

10@120+10@150

6@120+14@150

2@120+18@150

NOTE: For boilers 3000KW to 6000KW consult factory.

MODEL AND RATING PLATE

FOREWORD

APPROVALS

INSTALLATION CODE REQUIREMENTS

These designs comply with requirements of Underwriters Laboratories In addition to these instructions, the equipment 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.

and bear the U.L. label on the cabinet.

All models are built to the standards of Section lV of the American

Society of Mechanical Engineers. Boiler and Pressure Code,

inspected and identified by this symbol.

In absence of local codes the installation must comply with the latest

edition of the National Electrical Code, NFPA 70. Copies of this

document are available from the National Fire Protection Association,

1 Batterymarch Park, Quincy, MA 02269.

GROUNDING

Grounding and electrical wiring connected to the boiler must conform

to the latest edition of the National Electric Code, NFPA 70.

The ASME plate is located on the tank above the cleanout opening.

When specified, the National Board of Boiler and Pressure Vessel

Inspectors listing will be furnished and identified by an NB number on

the ASME plate.

Figure 1, below, is an illustration of a typical model NW/Commercial

Electric Hot Water Boiler with the features called out.

FEATURES

FIGURE 1

IMPORTANT

LOCATING THE BOILER

IT IS RECOMMENDED THATAQUALIFIED SERVICE TECHNICIAN For the best installation, the boiler should be located:

PERFORM THE INITIAL FIRING OF THE BOILER. AT THIS TIME

1. On a level surface.

THE USER SHOULD NOT HESITATE TO ASK THE TECHNICIAN

ANY QUESTIONS WHICH THEY MAY HAVE IN REGARD TO THE

OPERATION AND MAINTENANCE OF THE BOILER.

•

Shim the channel type skid base as necessary if leveling

is required.

BEFORE FILLING THE SYSTEM FOR OPERATION the hot water

system should be internally cleaned and flushed to remove any

contaminants which may have accumulated during installation. See

section of this manual titled SYSTEM CLEANING.

2. Near a floor drain.

• The boiler should be located in an area where leakage of

the tank or connections will not result in damage to the

area adjacent to the boiler or to lower floors of the

structure. When such locations cannot be avoided, a

suitable drain pan should be installed under the boiler.

RELIEF VALVE

An ASME rated pressure relief valve is furnished with the boiler. A

fitting for the relief valve is provided in the top of the boiler. A drain

line from the relief valve should terminate near a suitable drain. Do

not thread, plug, or cap the end of the drain line.

The pan should be at least two inches deep, have a

minimum length and width of at least two inches greater

than the dimensions of the boiler and should be piped to

an adequate drain.

The pressure setting of the relief valve should not exceed the pressure

capacity of any component in the system including the boiler.

•

The discharge opening of the relief valve should always

be piped to an open drain.

3. Suggested clearances from adjacent surfaces are found on a label

attached to the control compartment door.

HIGH TEMPERATURE DEVICES

Automatic Device

•

UL minimum clearances:

- 24” all sides

- 12” top

The boiler control circuit contains a high temperature cutoff switch.

This device shuts off the heating elements if excessive water

temperatures are reached. The high temperature cutoff has an

adjustable range of 100° to 240°F and automatically resets on a drop

of temperature.

•

Allow clearance for hinged control compartment doors.

Elements can be changed with 24” clearance.

Manual Device

4. The boiler may be installed in a confined space if adequate

ventilation is provided.

A manual reset high limit will be in the control circuit in addition to the

automatic device previously described. The control has an adjustable

range of 110° to 290°F and must be manually reset after a drop of

temperature.

ELECTRICAL

Reset button is located under the right side panel of the boiler.

Disconnect the power before removing the panel to push the button.

General

Check the boiler model and rating plate information against the

characteristics of the branch circuit electrical supply. Do not connect

the boiler to an improper source of electricity.

INSTALLATION

Voltage applied to the boiler should not vary more than + 5% to -10%

of the model and rating plate marking for satisfactory operation.

REQUIRED ABILITY

Do not energize the branch circuit for any reason before the boiler is

filled with water. Doing so may cause the heating elements to burn

out. Such damage is not covered under the terms of the warranty.

INSTALLATION OR SERVICE OF THIS BOILER REQUIRESABILITY

EQUIVALENT TO THAT OF A LICENSED TRADESMAN IN THE

FIELD INVOLVED. PLUMBING AND ELECTRICAL WORK ARE

REQUIRED.

The branch circuit is connected to the block through an opening

provided on top of the boiler.

The boiler should be connected to a separate, grounded, branch circuit

with overcurrent protection and disconnect switch. These are part of

the electrical supply system not components of the boiler, as such

they are obtained locally. The boiler should be grounded in accordance

with national and local codes.

GENERAL

Do not test electrical system before boiler is filled with water, follow

START UP procedure in this manual.

The principal components of the boiler are identified in Figure 1. The

model and rating plate, see illustration on page 4, provides certain

useful information required at installation. Both of these references

should be used to identify the boiler and its components.

Branch Circuit

The branch circuit wire size should be established through reference

to the National Electrical Code or other locally approved source in

conjunction with boiler amperage rating. Branch circuit wiring which

connects to the boiler terminal block should be temperature rated at

75°C. For convenience, portions of the wire size tables from the

Code are reproduced here. It is suggested the electrician size the

branch circuit at 125 percent of the boiler rating and further increase

wire size as necessary to compensate for voltage drop in long runs.

Branch circuit voltage drop should not exceed 3% at the boiler.

Water boilers are usually placed in series with the heating system on

the outlet side of the circulating pump. The boiler piping should include

inlet and outlet water valves to permit maintenance and service work

to be performed without disturbing the rest of the system.

Detailed system installation drawings are normally provided by the

equipment purchaser or system designer.

Calculating Amperage/Overcurrent Protection

Portion of Table 310-16

Allowable Ampacities of

Insulated Aluminum and Copper-

Clad AluminumConductors

Portion of Table 310-16

Allowable Ampacities of Insulated

Copper Conductors

The boiler is factory wired for connection to three wire single-phase

or three and four wire three-phase branch circuits. In addition, a

ground conductor may be required.

Not more than three conductors in

raceway or cable or direct burial

(based on ambient temperature of

30°C, 86°F.)

Not more than three conductors

in raceway or cable or direct

burial (based on ambient

A diagram of the wiring is furnished with the boiler for the electrician’s

use. An amperage table is on page 4 of this manual. The boiler

model and rating plate provides full load amperage data.

temperature of 30°C, 86°F.)

Temperature Rating of

Conductor. See Table

Temperature Rating of

Conductor. See Table

The rating of the overcurrent protection should be computed on the

basis of 125 percent of the total connected load amperage. Where

the standard ratings and settings do not correspond with this

computation, the next higher standard rating or setting should be

selected.

Size

AWG

MCM

310-13 in Code

Size

AWG

MCM

310-13 in Code

75°c

(167°F)

TYPES

75°C

(167°F)

TYPES

RH, RHW, RUH

(14-2),

THW, THWN,

(12-2),

THW, THWN,

Boiler Circuits

XHHW, USE

- - - - -

XHHW, USE

The boiler’s electrical components are pictured and identified on page

5. The model and rating plate illustration on page 4 identifies the

electrical characteristics. Basically, there are two electrical circuits:

•

The control circuit, where the temperature control directly or

indirectly operates the contactor coils.

100

115

100

120

135

155

180

205

230

250

270

310

340

375

385

395

425

445

485

520

545

560

1/0

2/0

3/0

4/0

250

300

350

400

500

600

700

750

800

900

1000

1250

1500

1750

2000

The power circuit, which is operated by the control circuit, carries

the electrical load of the heating elements.

130

150

175

200

230

255

285

310

335

380

420

460

475

490

520

545

590

625

650

665

1/0

2/0

3/0

4/0

250

300

350

400

500

600

700

750

800

900

1000

1250

1500

1750

2000

The following describes the circuits and includes typical wiring

diagrams. All circuits are designed for 60 or 50 Hertz alternating

current.

Refer to ELECTRICAL CONFIGURATION TABLE, below, and wiring

diagram provided with your boiler before completing connections to

electrical supply.

NOTE: Wiring diagrams in this manual are typical examples. The

specific wiring diagram for your boiler is the one supplied with the

boiler.

These capacities relate only to conductors

described in Table 310-13 in Code.

Control Circuit

For ambient temperatures over 30°C, see

Correction Factors, Note 13 in Code

All control circuits are operated on single-phase 120V. Atransformer

is used in the control circuit.

Power Circuit

Control circuit wiring is 14Awg, THHN or THWN type, rated 600 volts,

105°C.

The boiler is equipped with one of the power circuit configurations

shown in the table.

Seperate instructional literature is provided with the boiler for the

modulating solid state step control.

Power circuit wiring is type THHN, rated 600 volts, 105°C, sized as

necessary.

ELECTRICAL CONFIGURATION TABLE

Boiler

Nameplate

Markings

Voltage Phase

Type

Voltage Between

Boiler Terminal

Lugs

Control

Elements

Element

Circuit

Voltage

Quantity

Per

Service

Operating

Voltage

(1 Phase)

Contractor

120

208

120

208

Delta

(With

208

120

208

240

208

Neutral)

120

240

Delta

Wye*

Delta

120

240

277

480

240

480

1 or 2

1or 2

480

* Neutral lug not necessary and not furnished due to three wire wye connection. This means only three wires (no neutral)

brought to boiler due to method of element connection. Elements operate at 277 volts.

Voltage from a conductor to ground (electrical raceway and water pipes) is not measured.

No ground lug furnished. If required installer can provide locally.

TYPICAL WIRING DIAGRAMS

The following wiring diagrams are included in this manual to show

typical arrangements of electrical components in the control and

power circuits by voltage and phase charactreristics. They are

to be used as a reference by the installer or servicer in performing

their work. A diagram of the boiler wiring is furnished with the

boiler.

WIRING DIAGRAM 208V OR 240V THREE-PHASE (DELTA) WITH STEP CONTROL

WIRING DIAGRAM 480V THREE-PHASE (WYE)

SYSTEM CLEANING

OPERATION

The hot water system should be internally cleaned and flushed to

remove contaminants which may have accumulated during installation.

System cleaning provides chemical stability necessary for component

life and system performance.

GENERAL

Never operate the heating elements without being certain the boiler

is filled with water and a pressure relief valve is installed in the relief

valve opening provided.

Failure to clean the system may cause:

1. Poor heating due to formation of gas.

An electronic type low water cutoff is provided on all boilers as standard

equipment. The water probe is installed near the top of the tank to

monitor the presence of water. The control circuit is opened if the

water level is below this point.

•

Residual pipe dope, thread cutting oil, solder flux, dirt and

other foreign materials breakdown to form gas. This is

indicated by a continuing need for purging even through

the system is “closed”.

The pilot switch on the cabinet front permits the boiler to be turned on

and off without having to operate the electrical disconnect switch.

Additional switches may be provided for manually operating contactor

coils.

2. Pump seal leakage.

Acidic water (low pH) and contamination such as soil and

sand result in premature or recurring pump seal failures.

•

3. Automatic air valve leakage.

Contaminants cause sticky sealing surfaces and result in

leakage.

WARNING

•

Full power is present whenever the cabinet door is opened even with

the pilot switch(es) turned off. Never operate the boiler with cabinet

doors open or panels removed.

4. Relief valve operation.

Gas formation increases system pressure and relief valve

spillage.

•

FILLING

5. Water leaks at joints and fittings.

Corrosion and eventual failure of connections occur when

system pH is low.

Refer to SYSTEM CLEANING section for preparing the system prior

to final filling and operation.

•

Hard Water: in areas which have hard water it may be desirable to fill

the system with soft water and/or provide water treatment as

recommended by a consultant familiar with local conditions. In this

way harmful water scale build-up on the heating elements is minimized.

6. Noisy operation.

Heat transfer surfaces can be fouled with dirty, oily water.

•

This plus gas lead to noisy water circulation.

1. Close the boiler drain valve and system valves as necessary.

WARNING

Be sure to turn off power when working on or near the electrical system

of the boiler. Never touch electrical components with wet hands or

when standing in water. When replacing fuses always use the correct

size for the circuit.

2. Open a vent in the highest point of the system to allow the air to

escape.

3. Fully open the make-up water inlet valve. Fill the boiler and piping.

Tank flushing and circulating pump lubrication should be performed

in accordance with the above schedule. Tank sediment removal and

element lime scale removal must be performed when needed as

determined by period inspections. Following are the instructions for

performing recommended maintenance.

4. Close the vent as water starts to flow from the opening. Place the

make-up water valve in the desired position. The boiler is now

ready for START UP and TEMPERATURE REGULATION if being

placed in operation for the first time.

START UP

FLUSHING

The following checks should be made by the installer when the boiler

is placed into operation for the first time:

1. Turn off the electrical disconnect switch.

1. Check all factory and field made water and electrical connections 2. Open the boiler drain valve. Allow water to flow to an open drain

for tightness.

Repair water leaks and tighten electrical connections

as necessary.

until it runs clean. Do not come in contact with the water being

drained as it may be very hot.

•

3. Close the drain valve when finished flushing.

4. Turn on the electrical disconnect switch.

2. Turn on the electrical disconnect switch and pilot switch(es)

mounted on the boiler cabinet.

3. Observe the operation of the boiler during the first heating cycle.

SEDIMENT REMOVAL

•

Temperature control and contactor operation should be

checked by allowing the boiler to come up to temperature

and shutoff automatically.

Water borne impurities consist of fine particles of soil and sand which

settle out and form a layer of sediment on the bottom of the tank. In

time, if not removed, the level of sediment might reach the heating

elements.

TEMPERATURE REGULATION

For convenience, sediment removal and element lime scale removal

should be performed at the same time as follows:

Always turn off the electricity at the electrical disconnect switch when

making a temperature control adjustment.

It is suggested the temperature adjustment be turned to the lowest

setting which satisfies the hot water requirements of the system.

WATER AND LIME SCALE REMOVAL

•

Additional instructional literature is provided with the boiler for

adjusting this control.

Water and lime scale accumulations on the heating elements is a

normal condition, common to all immersion type elements. Factors

which affect the amount of this formation are:

Always close and lock the cabinet door after making a temperature

adjustment. Turn on electricity.

1. Amount of make-up water used. As the volume of make-up water

heated increases, more scale results.

DRAINING

2. Water temperature. As the temperature of the water is increased,

more scale is deposited on the elements.

The boiler must be drained if it is to be shut down and exposed to

freezing temperatures. Maintenance and service procedures may

also require draining the boiler.

3. Characteristics of water supply. Regardless of water treatment,

the elements should be examined regularly.

1. Turn off the electrical disconnect switch.

2. Close the make-up water valve and system valves as necessary.

3. Open a nearby outlet to vent the parts of the system being drained.

4. Open the boiler drain valve.

Water scale accumulations may cause noises to occur during

operation.

It is recommended that a lower heating element be removed

periodically for examination. If it is scaled, all of the elements should

be removed and cleaned. If the tank bottom has an accumulation of

sediment, it should be cleaned.

5. If the boiler is being drained for an extended shutdown, it is

suggested the drain valve be left open during this period.

• Follow FILLING instructions to restore boiler to service.

Lime scale should be removed from the elements by dissolving the

accumulation in UN•LIME^®delimer. UN•LIME is a non-muriatic

delimer, available through your dealer or distributor. Do not use muratic

or hydrochloric acid base deliming solutions to remove lime scale

from the elements. Do not pour delimer into tank.

MAINTENANCE

Boiler maintenance includes periodic tank flushing and cleaning, and

removal of lime scale from the heating elements. Circulating pumps

should be oiled.

All models:

1. Turn off electrical disconnect switch.

2. Drain the boiler following DRAINING instructions.

3. Remove the cabinet panel which covers the heating elements.

MAINTENANCE SCHEDULE

Component

Tank

Operation

Flushing

Interval

Monthly

Required

Sediment

Removal

Lime Scale

Removal

As Needed

As Needed UN•LIME^®

Delimer and

•

Remove insulation as necessary to reach the element

area.

Elements

element

gaskets.

Per pump makers

instructions

4. Remove the bolts from each element and remove the elements

from the opening.

Circulating

Pump(s)

Oiling

•

Disconnect element wiring as necessary.

•

Use a twisting, pulling action to remove elements scaled

beyond the size of the tank opening.

3. If the water was excessively hot, and is now cold, the high

temperature cutoff may have operated (manual reset equipped

models).

•

Brush loose scale from elements.

•

To reset, turn off electricity and remove the back panel

and push the reset button.

Silicates, sulfates and aluminates must be removed by

scraping or other mechanical means. Lime scale

dissolvents will not remove these types of scale which

are occasionally encountered.

•

Repeated operation of the high temperature cutoff should

be investigated by your servicer.

4. The capacity of the boiler may have been exceeded by a large

demand for heat.

5. Lime scale removal:

Place limed ends of heating elements into UN•LIME

•

Large demands require a recovery period to restore

water temperature.

•

delimer and allow scale to dissolve. Do not permit

delimer or water to contact heating element electrical

terminals.

5. Sediment or lime scale may be affecting boiler operation. Refer to

MAINTENANCE for details.

Water is too hot

6. Flush cleaned ends of elements with water when deliming or

cleaning is completed.

1. Refer to TEMPERATURE REGULATION.

7. Remove sediment and scale from the tank bottom through the

tank cleanout.

Boiler makes sounds

1. Sediment or lime scale accumulation on the elements may cause

sizzling and hissing noises when the boiler is operating.

•

The make-up water valve and boiler drain valve may be

opened to flush during the cleanout process.

•

The sounds are normal , however, the tank bottom and

elements should be cleaned. Refer to MAINTENANCE

for details.

8. Clean remaining gasket material from tank and element flanges.

Do not reuse original element gasket. The element gasket is Part

No. 5109.

2. Some of the electrical components of the boiler make sounds which

are normal.

9. Replace elements as follows:

•

Contactors will “click” or snap as the boiler starts and

stops.

•

Put a new gasket on each element.

Install into tank opening.

•

Transformers and contactors often hum.

Water leakage is suspected

Uniformly tighten element bolts. Torque to approximately

32 ft/lbs.

1. Check to see if the drain valve is tightly closed.

10. Connect element wiring as necessary.

2. If the outlet of the relief valve is leaking it may represent:

•

Excessive water pressure or air in the system.

Faulty relief valve.

11. Follow FILLING instructions to restore boiler to service.

•

Check for water leaks around elements and proper

operation when boiler is filled.

3. Examine the flange area of the elements and tank cleanout for

gasket leakage.

Replace insulation and cabinet panel.

•

Tighten the bolts or, if necessary, follow the WATER AND

LIME SCALE REMOVAL procedure to replace the

gaskets.

CHECKLIST

SYSTEM WATER TEST

Before calling for service, check the following points to see if the cause

of trouble can be identified and corrected. Reviewing this checklist

may eliminate the need of a service call and quickly restore the boiler

to service. The illustration on page 5 identifies the location of most of

the boiler components.

System water test

Review SYSTEM CLEANING section, for a description of six problems

which result from loss of system chemical stability. Chemical stability

is checked by:

BE SURE TO TURN OFF THE ELECTRICITY WHEN CHECKING

EQUIPMENT.

1. Draw off water from system. Is it dirty, discolored or odorous?

2. What is the pH of the system water? It should be neutral or slightly

alkaline.

Not enough or no heat

1. Be certain the electrical disconnect switch serving the boiler is in

the ON position. The pilot switch(es) on the cabinet front should

be on.

3. Does “air” purged from system vents burn? If so, the “air” is actually

gas.

•

In some installations the boiler electrical service may be

limited by the power company or boiler controls. If the

boiler operates on a controlled circuit heat may be

effected.

If any of the above conditions are present, all waterways should be

cleaned and the water adjusted to an alkaline condition.

If you cannot identify or correct the source of

malfunction:

2. Check the fuses.

1. Place the boiler electrical disconnect switch in the OFF position.

•

The electrical disconnect switch usually contains fuses.

2. Close the make-up water inlet valve to the boiler.

3. Contact your servicer.

•

The boiler has fuses located behind the cabinet door,

see page 5 for location.

NW-37 THRU NW-670 ELECTRIC HOT WATER BOILER LIMITED WARRANTY

A.O. Smith Corporation, the warrantor, extends the following LIMITED WARRANTY to the owner of this boiler.

1. THE TANK

If the tank in this boiler shall prove upon examination by the warrantor to have leaked due to natural corrosion from water therein, during

the FIRST year after initial installation, the warrantor will at its option, repair it or provide a replacement tank less elements

controls of equivalent size and then current model. Some government agencies are requiring energy efficient standards for boilers. In the

event regulations prohibit sale of a model of equivalent size and construction, A.O. Smith will provide a model which complies with

a n d

the regulations of your area, in which case the consumer will be charged the difference in price between the like replacement and the

energy efficient model required. The warranty on the repair or replacement of the part, portion or tank will be limited to the unexpired

term of the original warranty.

2. ALL OTHER PARTS

If within ONE year after initial installation of this boiler, any part or portion shall prove upon examination by the warrantor to be defective in

material or workmanship, the warrantor will repair or replace such part or portion at its option.

3. CONDITIONS AND EXPECTATIONS

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, a pressure relief valve, approved by the American Society

of Mechanical Engineers, must have been installed.

This warranty shall apply only when the boiler is used:

(1) at temperatures not exceeding the maximum setting of its control;

(2) at water pressure not exceeding the working pressure shown on the boiler;

(3) when filled with water, free to circulate at all times and with the tank free of damaging scale deposits;

(4) in a noncorrosive and non-contaminated atmosphere;

(5) in its original installation location;

(6) in the United States, its territories or possessions, and Canada.

(7) when operated free of the damaging effects of uncontrolled thermal expansion and/or water hammer.

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.

4. SERVICE AND REPAIR EXPENSE

Under this limited warranty the warrantor will provide only repair or a replacement tank or part thereof. The owner is responsible for all

other costs. Such costs may include but are not limited to:

Labor charges for service, removal, repair, or reinstallation of the tank or any component part;

Shipping, delivery, handling, and administrative charges for forwarding the new tank or replacement part from the nearest

distributor and returning the claimed defective tank or part to such distributor.

All cost necessary or incidental for any materials and/or permits required for installation of the replacement tank or part.

5. LIMITATION 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 tank or any of its parts. Some states do not allow limitations on how long an implied warranty lasts, so the above limitation

may not apply to you.

6. CLAIM PROCEDURE

Any claim under this 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 practicable, the owner should contact:

U.S. Customers

Canadian Customers

A.O. Smith Corporation

5621 W. 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

The warrantor will only honor replacement with identical or similar tank or parts thereof which are manufactured or distributed

by the warrantor.

Dealer replacements are made subject to in-warranty validation by warrantor.

7. DISCLAIMER

NO OTHER EXPRESS WARRANTY HAS BEEN OR WILL BE MADE IN BEHALF OF THE WARRANTOR WITH RESPECT TO THE

BOILER OR THE INSTALLATION, OPERATION, REPAIR OR REPLACEMENT OF THE TANK OR PARTS. THE WARRANTOR SHALL

NOT BE RESPONSIBLE FOR WATER DAMAGE, LOSS OF USE OF THE UNIT, INCONVENIENCE, LOSS OR DAMAGE TO PERSONAL

PROPERTY, OR OTHER CONSEQUENTIAL DAMAGE. THE WARRANTOR SHALL NOT BE LIABLE BY VIRTUE OF THIS WARRANTY

OR OTHERWISE FOR DAMAGE TO ANY PERSONS OR PROPERTY, WHETHER DIRECT OR INDIRECT, AND WHETHER ARISING

IN CONTRACT OR IN TORT.

Some states do not allow the exclusion or limitation of the incidental or consequential damage, so the above limitation or

exclusion may not apply to you.

This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

Fill in the following for your own reference. Keep it. Registration is not a condition of warranty. The model and ASME numbers are

found on the boiler’s rating plate.

Model No._______________________________________ASME No.___________________Date Installed__________________

Dealer’s Name____________________________________________________________________________________________

Dealer’sAddress_____________________________________________________________Phone No.____________________

City and State_______________________________________________________________Zip___________________________

KEEP THIS WARRANTY AND MANUAL POSTED ADJACENT TO THE BOILER FOR FUTURE REFERENCE WHENEVER MAINTENANCE, ADJUSTMENT OR

SERVICE IS REQUIRED. BE SURE YOUR DEALER HAS FILLED IN THIS WARRANTY.

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