A.O. Smith 960 through, 967 through User Manual

A.O.Smith

Cyclone XHE

Extra-High Thermal Efficiency

ELS COVERE

BTH Models 120 through 250

Series 960 through 967, 970 and 973

Service Handbook

Part No. TC-044R6 • Printed in the U.S.A. • 1105

Water Heaters

BTH Service Handbook

Introduction

Installation

Clearances Gas Requirements Venting

Air Requirements

Contaminated Air..........................

Flammable Items..........................

Multiple Unit Piping Condensation

Operation

Sequence of Operation

Controls........................................

Circuit Boards...............................

Troubleshooting

Pre-Service

120 VAC to Control

Transformer..................................

ECO Check

Temperature Probe

Pressure Switch Continuity . . Blower Pressure Switch Performance

120 VAC to Ignitor......................

Ignitor Resistance

Gas Valve Test...........................

Gas Pressure Check

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...................................

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3 . .4 -8 .9-11

........

.........18

. 19-20 .21-22

.........23

.........

24 .25-26 .27-28 .29-30

.........

Component Information

Orifice Tables Pressure Switches

Wiring Diagrams

Service Aids

BTH Muffler

Questions & Answers

Error Codes

Service Checklist.................................42

Parts Lists

970 & 973 Series...........................43-47

966 & 967 Series...........................48-59

960 Series 962 Series

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35-36

60-63

64-71

37 38

39 40

BTH SERVICE HANDBOOK

INTRODUCTION

This service handbook is designed to aid in servicing and troubleshooting A. O. Smith BTH 120 - 250 water heaters. No duplication or reproduction of this book may be made without the express written authorization of the A. O. Smith Water Products Company.

The following text and illustrations will provide you with a step by step procedure to verify proper installation, operation and troubleshooting procedures. Additional quick reference data is included to assist you in servicing this product.

The information contained in this handbook is designed to answer commonly faced situations encountered in the oper ation of the BTH product line and is not meant to be all inclusive. If you are experiencing a problem not covered in this handbook, please contact the A. O. Smith Technical Information Department at 1-800-527-1953 or your local A. O. Smith Water Products Company Representative for further assistance. This handbook is intended for use by licensed plumbing professionals and reference should be made to the instruction manual accompanying the product. This hand book contains supplemental information to the BTH instruction manual.

Qualifications: Installation or service of this water heater requires ability equivalent to that of a licensed tradesman in

the field involved. Plumbing, venting, gas supply and electrical testing skills are required.

Tools Required:

• Phillips head and flat tip screw drivers

• Set of marked drill bits

• Electric multimeter tester

• Gas pressure gauge or manometer (gauge — AOS part number 8099-2)

• Water pressure gauge (A OS part number 4798)

• Digital manometer or draft gauge

• Thermometer (AOS part number 4870 — range 0 thru 220°F)

• 1/2”, 1” and 11/8” sockets

• Pipe wrench for union disconnect

NOTE Also, have a copy of the instruction manual for the model and series BTH that you are servicing. Revision 2 includes:

• an added Multiple Venting statement on page 3 and a new Blower Motor Ohms Resistance Table on page 25. The Pressure Switch Table on page 32 was expanded/revised.

Revision 3 includes:

• clarification to Step 13, 14 and 15 Test.

• BTH 120 Propane information on pages 31,32, and the Parts List.

• revised part number — page 34, Step 11.

Revision 4 dated 04/02 includes:

• expanded error code information on page 36.

"fRevision 4 dated 04/03 includes:

• revised sequence of troubleshooting. Minor corrections.

Revision 6 includes:

• 970 & 973 Series product information. Minor corrections.

f. Handbook cover should have stated revision 5.

Technical Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

INSTALLATION

CLEARANCES

This portion of the handbook will review often overlooked installation require

ments. The installation manual covers these items in detail. BTH water heaters are approved for installation on com

bustible flooring. The minimum clear ance to combustibles or non

LEFT

combustibles is 0 inches from the sides waLiI and rear, 0 inches from vent piping, and

1.5 inches from the top cover. A 24 inch top view

clearance for all serviceable parts is

recommended. Clearances may vary

between BTH models. See installation

manual or the label on the heater for your specific model.

CEILING

‘1.5

FRONT VIEW

*For removal of top cover

WALL

RIGHT WALL

REAR WALL

l_gpj

. 0" ,

.ÜT

RIGHT

WALL

GAS REQUIREMENTS

NOTE: Pressure without capacity will result in lockout. Follow the piping guidelines in the

installation manual. The supply gas pressure is normally measured at the dirt leg or at the inlet gas

pressure tap on the gas valve. This reading must be measured with ‘flowing’ gas. The manifold gas pressure is measured at the manifold pressure tap on the gas valve when the

gas is flowing. The gas valves used on all BTH water heaters are 24 VAC combination step open

ing gas valves. They incorporate the main valve and pressure regulator into one body.

REGULATED GAS SUPPLY LINE

GAS SUPPLY SPECIFICATIONS

NATURAL GAS NATURAL GAS PROPANE GAS

PRESSURE REGULATOR ADJUSTMENT (COVER screw'

INLET PRESSURE TAP

GAS INLET

BTH 120 & 250 BTH 150 & 199

GAS VALVE ON/OFF

TH & TR TERMINALS (MAIN VALVE)

VIANIFOLD

PRESSURE TAP

GAS OUTLET

BTH 120, 150 &

199

Max. Gas Supply Pressure Inches W.C.

Nominal Gas Supply Pressure Inches W.C.

Minimal Gas Supply Pressure Inches W.C.

Manifold Pressure Inches W.C.

12.0 (3 kPa) 12.0 (3 kPa) 14.0(3.45 kPa)

7.0 (1.75 kPa) 7.0 (1.75 kPa) 11.0 (2.74 kPa)

5.5 (1.37 kPa) 4.5 (1.12 kPa) 11.0 (2.74 kPa)

4.0 (1 kPa) 3.5 (0.8 kPa) 10.0 (2.5 kPa)

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

NSTALLATION

VENTING

Equivalent Feet of Pipe Intake or Exhaust

VENT LENGTH TABLE

NUMBER OF 90°

ELBOWS

ONE (1)

TWO (2)

THREE (3) 7 35 105

FOUR (4) 7

FIVE (5) 7

SIX (6) 7

3” MINIMUM

PIPE (FEET)

7 45 115 7

3” MAXIMUM

PIPE (FEET)

40 110

30 100

- 95

4” MAXIMUM

PIPE (FEET)

4-inch PVC may be used for a MAXIMUM intake of ONE HUNDRED TWENTY (120) EQUIVALENT

FEET and a MAXIMUM exhaust of ONE HUNDRED TWENTY (120) EQUIVALENT FEET The

maximum number of 90° elbows with the 4-inch venting is six (6) on the intake and six (6) on the exhaust. A 90° elbow is equal to five (5) equivalent feet of pipe. One (1) 90° elbow is equal to two (2) 45° elbows. Any venting configuration using less than 50 equivalent feet should use 3-inch vent ing. See Vent Length Table.

The 3-inch venting terminals (provided) must be used with the 4-inch venting by adding 4x3 reducing coupling at the venting terminals. A reducing coupling is also needed immediately after the condensate elbow (exhaust) and immediately before the 3-inch blower adapter (intake) if direct venting is installed. See Vent Length Table.

DIRECT VENTING

The air intake provided on the unit contains a mesh screen (see Figure below) to prevent large par ticles from entering the unit.

3” (7.6CM) 45° PVC ELBOW WITH MESH SCREEN

MESH

SCREEN

WARNING

WHEN THE UNIT IS TO BE SETUP AS A DIRECT VENT, THE MESH SCREEN MUST BE REMOVED. THE INLET VENT PIPE MAY THEN BE GLUED TO THE AIR INTAKE (see follow

RESTRICTOR

ing Figure) PROVIDED ON THE UNIT.

Technical Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

IC IC IC IC IC IC IC

—p l_l l_l

SEALED DIRECT VENT VERTICAL

z[#

BTH SERVICE HANDBOOK

INSTALLATION

VENTING CONFIGURATIONS

SEALED DIRECT VENT SIDEWALL

INDOOR CONVENTIONAL

VERTICAL

IE EE EE EE EE EE EE EE EE

INDOOR CONVENTIONAL

SIDEWALL

SEALED DIRECT VENT

HORIZONTAL INTAKE

VERTICAL EXHAUST

This unit can be vented using only PVC (Class 160, ASTM D-2241; Schedule 40, ASTM D-1785; or Cellular Core Schedule 40 DWV, ASTM F-891), Schedule 40 CPVC (ATSM F-411), or ABS (ASTM D-2661) pipe. The fittings, other than the TERMINATIONS should be equivalent to PVC-DWV fit tings meeting ASTM D-2665 (Use CPVC fittings, ASTM F-438 for CPVC pipe and ABS fittings, ASTM D-2661/3311 for ABS pipe. If CPVC or ABS pipe and fittings are used, then the proper cement must be used for all joints, including joining the pipe to the Termination Tee (PVC Material). PVC Materials should use ASTM D-2564 Grade Cement; CPVC Material should use ASTM F-493 Grade Cement and; ABS Materials should use ASTM D-2235 Grade Cement.

For water heaters in locations with high ambient temperatures (above 100°F) and/or insufficient dilution air, it is recommended that CPVC or ABS pipe and fittings (MUST USE SUPPLIED VENT TERMINAL) be used.

SEALED DIRECT VENT

VERTICAL INTAKE

HORIZONTAL EXHAUST

VENTING MATERIALS

SEALED DIRECT VENT

W/ CONCENTRIC VENT

VERTICAL TERMINATION

SEALED DIRECT VENT W/ CONCENTRIC VENT

HORIZONTAL TERMINATION

Technical Training Department

TC-044 Revision 6

ВТН SERVICE HANDBOOK

INSTALLATION

CONCENTRIC VENT TERMINATION

The concentric vent termination kit, Part No. 194451-000 can be used on BTH 120 - 250 Cyclone XHE water heaters. It adds zero equivalent feet to the vent system. Below are some general appli cation and installation guidelines for the concentric vent kit. Refer to the accompanying literature and the water heater installation manual for complete venting installation instructions.

This concentric vent termination kit may be used with 3 or 4 in. diameter pipe systems. When con necting to a 4 in. diameter pipe system a 3 x 4 in. field supplied reducer is to be installed at the intake and exhaust connection of the concentric vent termination kit. See water heater installation and operation manual for venting specification

3" DIAMETER PVC VENT/EXHAUST

4" DIAMETER

Dimension 21 1/8 in. may be lengthened to 60 in. maximum. Dimension 21 1/8 in. may also be shortened by cutting the pipes, provided in the kit, to 12 in. minimum. Dimension 39 will change accordingly as dimension 21 1/8 in. is lengthened or shortened

MAINTAIN 12 IN.

VENT

(18 IN. FOR CANADA)

Vertical Installation

Technical Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

INSTALLATION

VENTING CLEARANCES

This illustrates the exterior clearances for these BTH units when installed as direct vent heaters. NOTE: 24 inches between inlet and outlet is a MINIMUM. Greater distance is recommended.

In colder climates increasing the 24” minimum to a maximum practical distance will reduce the possibility of frost over from side winds blowing exhaust vapors into the air intake.

BTH MODEL 120

BTH MODEL 150-199

BTH MODEL 250

EXHAUST

VENT

TERMINAL

SIDE WALL

INTAKE

VENT^

TERMINAL

--J II

-JU iL_«

■ —*1

PLUMBING VENT ROOF BOOT

(TVP. BOTH PIPES) 24* MIN

PLUMBING VENT

ROOF BOOT

(TYP. BOTH PIPES) 24

—] II

1! i

EXHAUST

n II

VENT

TERMINAL

A SB; 12° ABOVE ROOF OR SNOW ACCUMULATION LEVEL

A & B ; 12* ABOVE ROOF OR SNOW ACCUMULATION LEVEL

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TC-044 Revision 6

BTH SERVICE HANDBOOK

NSTALLATION

EXTERIOR SIDEWALL CLEARANCES

Horizontal Vent (Using Room Air for Combustion)

When multiple units are directly vented through a wall, all intake vent terminals must be no lower

than the highest exhaust vent terminal.

CAUTION

DO NOT TERMINATE THE VENTING WHERE NOISE FROM THE EX

HAUST OF INTAKE WILL BE OBJECTIONABLE. THIS INCLUDES LOCATION CLOSE TO

OR ACROSS FROM WINDOWS AND DOORS. AVOID ANCHORING THE VENT AND

INTAKE PIPES DIRECTLY TO FRAMED WALLS, FLOORS OR CEILINGS UNLESS RUB BER ISOLATION PIPE HANGERS ARE USED. THIS PREVENTS ANY VIBRATIONS FROM BEING TRANSMITTED INTO THE LIVING SPACES.

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A. O. Smith Water Products Co.

ВТН SERVICE HANDBOOK

INSTALLATION

AIR REQUIREMENTS

MINIMUM AIR FOR COMBUSTION

10 Cubic Feet of Air Per 1000 BTUH

2.5 CU.

EXCESS

AIR

Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1000 BTUH of gas input. The National Fuel Gas Code also recommends an additional 2.5 cu.ft. of “excess air”. This 12.5 cu.ft. minimum supply air per 1000 BTUH input applies to natural and propane gas mod els.

The National Fuel Code also specifies minimum make-up air opening sizes for various building installations (Ref: NFPA 54, ANSI Z223.1, sec 5.3).

MAKE-UP AIR

Direct Vent Installation

This model is approved for direct venting either horizontally or vertically or conventional venting horizontal or vertical. Direct venting avoids using room air for combustion and eliminates the need for additional air intake ducts.

A. O. Smith Water Products Co.

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

INSTALLATION

MAKE-UP AIR

Direct Communication

12”

Each opening shall have a free area not less than:

1 square inch per 4000 BTUH total input all appliances within the enclosure

Inlake Air

Iniciko Air Opening

Opening

12”

A fresh supply of make-up air for combustion can be supplied to the heater through make-up air

openings, which directly communicate with the out of doors. Two openings are required — one

within 12 inches of the top of the enclosure and one within 12 inches of the bottom of the enclosure.

Each opening shall have a free area of not less than 1 square inch per 4000 BTUH of the total input

of all appliances within the enclosure. The lower opening is primarily providing combustion air. The upper opening is providing vent dilu

tion air and acts as a relief opening for flue gases should the vent become obstructed or a down

draft condition occur.

MAKE-UP AIR Vertical Ducts

Air Intake Ducts

12”

Each opening shall have a free area not less than:

1 square inch per 4000 BTUH total input all appliances within the enclosure

12”

Often it is more practical to install vertical make-up air ducts to the outdoors. Again, two openings are required — within 12 inches (30 cm) of the top of the enclosure and one within 12 inches (30 cm) of the bottom of the enclosure. Each opening shall have a free area of not less than 1 square inch per 4000 BTUH of the total input of all appliances within the enclosure.

Technical Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

NSTALLATION

MAKE-UP AIR

Horizontal Ducts

E.K ÌÌ opiMiin<| sImII

hriVH <-1 liee nnl

less

IImm:

1 s(|ii<iie im li pel vomì BTUH Ifil.il inpiil , «ill «ippliano os within llie ent Insule

Air Intake Ducts

12”

12’

When the heater is installed in an interior room with no roof access for vertical ducts, horizontal make-up ducts should be installed. When using horizontal ducts, two openings are required - within

12 inches (30 cm) of the top of the enclosure and one within 12 inches (30 cm) of the bottom of the enclosure. Each opening shall have a free area of not less than 1 square inch per 2000 BTUH of the total input of all appliances within the enclosure.

INSUFFICIENT MAKE-UP AIR

Backdraft

Insufficient make-up air is a major cause of combustion problems. One common example is in a restaurant installation where exhaust vent equipment was not considered in sizing make-up air requirements. This may result in air being backdrafted by the restaurant exhaust equipment through the heater causing flue gas spillage, flame roll out, improper combustion, inconsistent pilot operation, and/or erratic heater shutdown.

A possible solution to this situation would be to use a BTH with direct venting. A less common service issue associated with a backdraft or negative pressure room would be the

opening or closing of air pressure switches. This may result in erratic or no heater operation.

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

INSTALLATION

CONTAMINATED AIR

^ RUST

CHIPS

Along with adequate make-up air, the quality of the air is important. Contaminants in combustion air can lead to premature heater failure. Vapors from bleaches, soaps, salts, etc. are drawn into the combustion chamber with the make-up air and, once fired, mix with water vapor in the gasses to form extremely corrosive hydrochloric or hydrofluoric acid and other corrosive by-products. Dust drawn in may build up on the blower or clog the main burner ports. Also, be certain to examine the exterior area around the air intake of a direct vent installation for the contaminants.

FLAMMABLE ITEMS

Flammable items or pressurized containers or any other potentially hazardous articles must never be placed on or adjacent to the heater. Open containers of flammable material should not be stored

or used in the same room with the heater or in the area of the exterior air intake of a direct vent

installation. Direct venting does not eliminate the need to remove flammable or corrosives from the

area surrounding the heater.

Technical Training Department

TC-044 Revision 6 12

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

INSTALLATION

MULTIPLE UNIT — WATER PIPING

A. O. Smith Water Products Co.

Technical Training Department

TC-044 Revision 6

ВТН SERVICE HANDBOOK

INSTALLATION

CONDENSATION

The average dewpoint of natural gas flue products is 127° F. Propane flue products is 119° F. With

70° F ambient air temperature and 180° F stored water temperature, exhaust gas will be approxi mately 140° F. Recommended starting point for water storage is 120° F.

The extra high thermal efficiency of the BTH will result in condensation in the flue passage. The fol

lowing answers common questions about this condensation. CAN I DRAIN THIS CONDENSATION TO A FLOOR DRAIN? The “Corrosion Resistance of Cast

Iron Soil Pipe” by the Ductile Metals Association (formally the Cast Iron Soil Pipe Institute) states

that: “Internal corrosion of cast iron soil pipe and fittings can be caused by strong acids or other reagents

having an acidity of pFI 4.3 or less if allowed to contact cast iron pipe for an extended period of time without sufficient dilution to raise the pH valve about 4.3. By avoiding low pH discharges, internal corrosion problems can be limited or eliminated, assuring the owner many years of service.”

WHAT ABOUT THE pH VALUES OF CONDENSATE AND SODA POP? The pH of the BTH con densate average 4.5 which is approximately 4 times less concentrated than the limit of 4.3 recom

mended by the DMA. Any water flow in the drain rapidly dilutes the condensate even more. A can of leading carbonated cola drink measured a pH of 2.5 which is 300 times more concentrated than the BTH condensate.

WHAT DOES THE pH SCALE MEAN? The pH value is a measure of acidity of alkalinity. A pH of

7 is neutral. Numbers from 7 to 1 indicate increasing acidity and numbers from 7 to 14 indicate

increasing alkalinity. The pH scale is similar to the Richter scale used to measure earthquakes.

Each number indicates a change of 10 times the concentration of the previous value. A pH 6 is 10 times more concentrated than a pH 7, a pH 5 is (10x10) 100 times pH 7 and pH 4 is (10x10x10)

1,000 times pH 7, etc. WHAT ABOUT CONDENSATE NEUTRALIZERS? Condensate neutralizers are usually not nec

essary. A condensate neutralizer is easy to make by filling a short length of 2” or 3” PVC pipe with

landscape marble chips, capping it and installing it in series with the condensate drain of the equip

ment. Most commercial neutralizers are off the market because of poor demand for the product. Condensation from the exhaust vent piping and tank internal flue way must be allowed to drain. A “blocked flue” indication will often be your first indication that condensate is not draining.

Technical Training Department

TC-044 Revision 6 14

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

OPERATION

SEQUENCE OF OPERATION

A. O. Smith Water Products Co.

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

OPERATION

CONTROLS

NORMAL INDICATIONS / READINGS / SETTINGS

During Call for Heat

On/Off switch in the “on” position

DISPLAY PANEL (CONTROL PANEL)

Water Temperature F° — current average tank water temperature displayed

120 VAC LED light on 24 VAC LED light on High LimitA/ent Switch LED light on Blower (while blower is running) LED light

on Air Pressure Switch (while blower is

running) LED light on Control Status LED light on Gas Valve (during ignition period and

heating cycle) LED light on

The water temperature inside the tank must be below the current temperature setting to activate a call for heat. Pressing the Set/Reset button approximately 4-6 seconds after powering up the water heater will reveal the current temperature setting. See the instructions below for how to view or change temperature settings.

Power On Display Sequence / Indication

120

--------

M Press Set/Reset button at this moment |

¡to initiate a control operational check i

1 Factory default setting - 12. ¡

¡Tank Temperature

Press Set/Reset button to view or

ladjust current temperature setting.

Power on display. j

¡Supply voltage i

j ¡Temperature Offset. i

To View Or Change Temperature Settings

Press the Set/Reset button once to view the current temperature setting.

' 1

Press and hold the Set/Reset button down to change the current setting.

When pressed and held down it will raise/lower the setting, quickly releasing and pressing down/holding again will switch between raising and lowering. When the desired setting is reached release the button.

The control must satisfy a call for heat with the new setting for the new setting to remain in memory. If the water heater does not satisfy a cali for heat with the new setting, the new setting is lost and the previous setting remains in effect.

Technicai Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

OPERATION

CIRCUI BOARDS

DISPLAY CIRCUIT BOARD

IGNITION CIRCUIT BOARD

'1... 2.1.4

■ -1 - •

■ ■ *

20 Conductor

. Ribbon Cable

to Display Board • • ‘ ^ ^ 'j. J 4—

is»

.....................................

■ -tj tCN2 , 12 3

, (tHaií>í*3í--í

....

, J .^Transformer

CN1

CN6 j:r>

1 2

' i '*

1 2 3 ;

3 2 1

6 5 4

4»-

1 1 2 •

.Temperature/

Eco Probe (Upper)

Temperature

Probe #2 (Lower)

Igniter

Blower

To Junction Box

1,3 Gas Valve

2 Flame Sensor

4,6 Pressure Switches

5 Ground

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

TROUBLESHOOTING

PRE-SERVICE TIPS

CHECK THAT:

• Insure 120 VAC power supply has correct polarity — check neutral (white) wire to ground with volt meter. It should read “0” volts.

• Tank is full of water

• Exhaust and intake vent do not exceed allowable limits

• All plugs into boards are secure

• Condensate hose is drained and open

• Proper (natural or propane) gas is supplied

120 VAC TO CONTROL

STEP 1 120 VAC TO CONTROL BOARD

j1 2 3 4 N«!

M. -a«*-

1 2

:1|CN4 ■ . ■ ^

it;* ViiRitcB*

iCN2 . 12 3

STEP 1: CHECK FOR 120 VAC TO CONTROL BOARD CN1 TERMINAL.

Condition:

• Disconnect plug from CN1 terminal.

• On/Off switch is on.

12 3 4

■ ■

CN1

• G 5 4 •

. 0 , ■

j i.mi TR'ig

To Juiiction Box

■ Black " White " Green

Check for 120 VAC black wire terminal white wire on plug.

IF... THEN

120 VAC is not present

120 VAC is present reconnect CN1 plug, continue to Step 2.

Technical Training Department TC-044 Revision 6

check On/Off switch, turn switch on, replace On/Off switch if defective, restore power to the water heater.

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

TROUBLESHOOTING

TRANSFORMER

STEP 2

120 VAC TO TRANSFORMER

I 120V

m-%

^ o

i'iC —

^ lonThois

STEP 2: CHECK FOR 120 VAC TO TRANSFORMER FROM PIN 1 AND 2 ON CONTROL BOARD CN4 TERMINAL.

Condition:

• Disconnect CN4 plug from control board.

• On/Off switch is on.

Check for 120 VAC between pin 1 and 2 at CN4 on the control board as illustrated above. Perform this test with the CN4 plug disconnected and the On/Off switch turned on.

IF... THEN

120 VAC is not present

120 VAC is present reconnect CN4 plug to control board, continue to Step 3.

check CN1 plug connection

replace control board if Step 1 has been performed and results were successful.

A. O. Smith Water Products Co.

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

TROUBLESHOOTING

TRANSFORMER (CONTINUED)

STEPS

24 VAC FROM TRANSFORMER

‘m ■'■

STEP 3: CHECK FOR 24 VAC AT TRANSFORMER CN4 PLUG ON CONTROL BOARD.

Condition:

• CN4 is plugged into control board.

• On/Off switch is on.

Insert meter probes into back of CN4 plug on pins 3 and 4 (blue and yellow wires) with CN4 plugged in and power on.

IF... THEN

24 VAC is not present 24 VAC is present

replace transformer if Steps 1 and 2 were performed and results were successful. continue to Step 4.

Technical Training Department TC-044 Revision 6

A. O. Smith Water Products Co.

BTH SERVICE HANDBOOK

STEP 4 24 VAC TO ECO

TROUBLESHOOTING

ECO CHECK

24 V

Black Black

Redj I j |Red

Ground

_ t.

1 2 3

I ^'12 •

7^CN8 ◄

1 2

■CN5 -

I 1 I 'i A

STEP 4: CHECK FOR 24 VAC BETWEEN PIN 4 ON CONTROL BOARD TERMINAL CN3 AND GROUND.

Condition:

• Disconnect CN3 plug from control board.

• On/Off switch is on.

Check for 24 VAC between pin 4 of the CN3 terminal on the control board and ground.

IF... THEN

24 VAC is not present

replace the control board if Steps 1, 2, and 3 have been performed and the results were successful.

^Temperature/

Eco Probe (Upper)

^Temperature

-----

Probe #2 (Lower)

-Igniter

24 VAC is present continue to Step 5.

Technical Training Department

TC-044 Revision 6

BTH SERVICE HANDBOOK

TROUBLESHOOTING

ECO CHECK (CONTINUED)

STEPS 24 VAC FROM ECO

24 V

1 2

.Temperature/

Eco Probe (Upper)

Temperature

», Probe #2 (Lower)

2 I-

Igniter

IcN4 .^ ^ ^

' Í ^

. [ *

TCN2 1 2 3

■ 1 O *5

CN1 HtnwISKflp^—To Junction Box

I I

6 5 4

Transformer

— Blower

1, 3 Gas Valve 2 Flame Sensor

• 4, 6 Pressure Switches

5 Ground

STEP 5: CHECK FOR 24 VAC BETWEEN PIN 1 ON CN3 PLUG AND GROUND.

Condition:

• Reconnect CN3 plug to control board.

• On/Off switch is on.

Insert one meter probe into the back of CN3 plug pin 1, check for 24 VAC between here and ground with CN3 plugged in and power on. (See illustration above for pin number locations.)

IF... THEN

make sure water temperature in tank is below 160° F, press Set/Reset button on

24 VAC is not present

24 VAC is present continue to Step 6.

Technical Training Department

TC-044 Revision 6 22

display panel, replace upper temperature/ECO probe if tank water temperature is

below 160 and Step 4 has been performed and results were successful.

A. O. Smith Water Products Co.

+ 51 hidden pages

A.O. Smith 960 through, 967 through User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Extra-High Thermal Efficiency

TABLE OF CONTENTS

INTRODUCTION

INSTALLATION

DIRECT VENTING

VENTING CONFIGURATIONS

VENTING MATERIALS

CONCENTRIC VENT TERMINATION

VENTING CLEARANCES

MAKE-UP AIR Vertical Ducts

OPERATION

To View Or Change Temperature Settings

DISPLAY CIRCUIT BOARD

IGNITION CIRCUIT BOARD

TROUBLESHOOTING