A.O. Smith BTC 201 Installation manual

Induced Draft Multi-Flue

Commercial Water Heaters

M O D E L S C O V E R E D

BTN Models 120 through 400 (A)

Series 100 through 108

(BTN Meets Low NOx Requirements of SCAQMD Rules 1121 and 1146.2)

BTR Models 151, 201

Part No. 317923-000 • Printed in the U.S.A. • 0810

BTN,BTR 151/201 TANK TYPE COMMERCIAL

GAS WATER HEATER SERVICE HANDBOOK

Table of Contents

BTN, BTR 151/201 SERVICE HANDBOOK INTRODUCTION..............................................2

QUALIFICATIONS..................................................................................................................3

TOOLS REQUIRED...............................................................................................................3

INSTALLATION CONSIDERATIONS - CLEARANCES.........................................................4

TOP AND FRONT VIEWS OF MINIMUM CLEARANCES TO COMBUSTIBLES..................4

MINIMUM CLEARANCE TO COMBUSTIBLES.....................................................................5

REQUIRED EXTERIOR CLEARANCES................................................................................6

AIR SUPPLY..........................................................................................................................7

INSUFFICIENT MAKEUP AIR ........ NEGATIVE AIR PRESSURE .....DOWNDRAFTS........7

MAKE-UP AIR – DIRECT COMMUNICATION WITH OUTDOORS.......................................8

CONTAMINATED AIR............................................................................................................9

AIR FOR COMBUSTION – FLAMMABLE ITEMS..................................................................9

GAS VALVE.........................................................................................................................10

GAS VALVE.........................................................................................................................11

VENTING.............................................................................................................................12

VENTING – MULTIPLE CATEGORY I GAS WATER HEATERS.........................................12

VENT TABLES FOR CATEGORY I - TYPE B GAS VENT..................................................13





BTN /BTR 151,201 SEQUENCE OF OPERATION..............................................................18

DRAFT PROVING PRESSURE SWITCH - SETTINGS.......................................................19

THERMOSTAT AND IGNITION CONTROL BOARD VIEW.................................................20

WHITE RODGERS INTEGRATED CONTROL - THERMOSTAT........................................21

WHITE RODGERS IGNITION CONTROL BOARD..............................................................22

GAS CONTROL VALVE/BURNER AREA VIEW..................................................................23

WIRING DIAGRAM..............................................................................................................24

ELECTRICAL SEQUENCE – BTN / BTR151,201................................................................25

OPERATING SEQUENCE – FLOW CHART........................................................................26

DIAGNOSTIC SEQUENCE OF OPERATION – FLOW CHART..........................................27

PRE-SERVICE CHECKLIST................................................................................................28

TEST 1 - 120 VAC CHECK TO HEATER.............................................................................29

HEATER CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND

TROUBLESHOOTING.........................................................................................................29

IGNITION CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND

A. O. Smith Water Heaters

Ashland City, Tennessee © 2 0 0 7

1 Technical Training Department



TROUBLESHOOTING..........................................................................................................30

TEST 2 - POLARITY CHECK...............................................................................................31

TEST 3 - CONTINUITY CHECK OF HIGH LIMIT (ECO)......................................................32

TEST 4 - UPPER TEMPERATURE PROBE CONTINUITY CHECK....................................33

TEST 5 - CALLING FOR HEAT – NO INDUCER OPERATION...........................................34

TEST 6 - INDUCER ON.............NO IGNITION.....................................................................35

TEST 7 - INDUCER ON – PROVER SWITCH AND LOW GAS SWITCH CLOSED

...................NO IGNITER OPERATION................................................................................36

TEST 8 - IGNITER HEATS – NO MAIN BURNER................................................................37

TEST 9 - IGNITER HEATS – NO MAIN BURNER................................................................38

TEST 10 - MAIN BURNER IGNITION FOR LESS THAN 5 SECONDS...............................39

TEST 11 - WATER HEATER SHUTTING OFF BELOW SETTING......................................40

DISPLAY LIGHTS ON INTEGRATED HEATER CONTROL................................................41

GENERAL QUESTIONS AND ANSWERS ..........................................................................50

BTN, BTR 151/201 SERVICE HANDBOOK INTRODUCTION

This service handbook is a supplement to the BTN and BTR151/201 Installation and

Operation Manual. The handbook provides information on servicing and troubleshooting A.O.

Smith BTN/BTR151,201/ water heaters in the field. While this handbook is not intended to be all inclusive, it contains:

• step-by-step procedures with illustrations to verify proper installation, operation,

and troubleshooting

• quick reference data to assist in servicing the product line

• answers to common questions encountered in the operation of the product line.

The handbook is intended to be used by licensed plumbing professionals. Reference should be made to the installation manual accompanying the product. 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. No duplication or reproduction of this book may be made without the expressed written authorization of the A.O. Smith Water Products Company.






QUALIFICATIONS

Installation or service of this water heater requires ability equivalent to that of a licensed tradesman in the field involved. Plumbing, air supply, venting, gas supply and electrical testing skills are required.

TOOLS REQUIRED

• Phillips head screwdriver

• standard screwdrivers

• 3/8 and 7/16 inch open end wrench

• set of marked drill bits

• electrical multimeter tester capable of measuring continuity, AC voltage and DC

voltage

• gas pressure gauge or manometer

• water pressure gauge

• thermometer

• 1/2 inch socket with extension for removal of the clean out cover

• 1-1/16 inch socket with extension for anode removal

Rev. 1 - Adds multi-flue models. BTN and are identical except for nitrous oxide (NOx) emission bars over main burner ports on BTN models.

Rev. 2 - Corrected clearance table illustration errors and clarified troubleshooting procedures.

Rev. 3 Adds BTR 151 & 201 models. Adds BTN Series 108 to parts list. BTI models no longer in production.






INSTALLATION CONSIDERATIONS - CLEARANCES

This portion of the handbook reviews some often overlooked installation considerations clearances, air supply, gas pressure requirements, and venting—taking note of necessary installation requirements for BTN and BTR151,201 . The installation manual covers most of these items in detail.

A 24-inch clearance for all serviceable parts is recommended. Clearances may vary between models. See instruction manual or the label on the heater for clearances applicable to your specific model.

TOP AND FRONT VIEWS OF MINIMUM CLEARANCES TO COMBUSTIBLES






MINIMUM CLEARANCE TO COMBUSTIBLES

Model Number

-120

-154

-180 thru 199

-200/A thru 275/A

-310 thru 400/A

BTN-120 thru

200A

BTN-250/A thru

310/A

BTN-366

BTN-400

BTR 151 & 201

"A" Right Side

2"

1"

3"

2"

3"

2"

3"

6"

4"

2”

"B" Left Side

2"

1"

3"

2"

3"

2"

3"

6"

4"

2”

"C" Back "D"

2"

1"

3"

2"

3"

2"

3"

6"

4"

2”

Ceiling

12"

12"

12"

12"

12"

12"

12"

6"

4"

12”

A, B, and C clearances to non-combustibles is “0” inches - a 12 inch clearance to cover remains unchanged.






REQUIRED EXTERIOR CLEARANCES

The illustration below shows the required clearances for venting units using natural draft venting.

The vent must extend at least 3 feet above the highest point where it passes through a roof of a building and at least 2 feet higher than any portion of a building within a horizontal distance of 10 feet (for vents of 12 inches in diameter or less).

References: NFPA 54 ANSI Z 223.1 may allow reduction to 8 feet with a “listed vent cap.”

“ Copyright by the American Gas Association. Used by permission of the copyright holder” .






AIR SUPPLY

Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1,000

User-Defined Index

building installations, refer to the National Fuel Gas Code NFPA 54, ANSI Z223.1, Sec. 5.3

Feet

Com. Air

2.5 Cubic

Feet

Excess

Air

INSUFFICIENT MAKEUP AIR ........ NEGATIVE AIR PRESSURE .....DOWNDRAFTS

One common example is in a restaurant installation where exhaust vent equipment was not considered in sizing make-up requirements. This condition may result in air being back drafted by the restaurant exhaust equipment through the heater causing the draft proving switch to open and/or erratic heater shutdown.






MAKE-UP AIR – DIRECT COMMUNICATION WITH OUTDOORS

A fresh supply of make-up air for combustion can be supplied to the heater through make-up air ducts, which directly communicate with the outdoors.(Not Direct Vent)

1 SQUARE INCH PER

4,000 Btu FOR EACH

OPENING

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 must have a free area of not less than 1 square inch per 4,000 BTUH of the total input of all appliances within the enclosure. The lower opening primarily provides combustion air. The upper opening provides vent dilution air and acts as a relie opening for flue gases should the vent become obstructed or a downdraft condition occur.

Additionally, when the heater is installed in a confined space and communicating with the outdoor air, one permanent opening, beginning within 12 inches (30 cm) of the top of the enclosure, must be permitted where the equipment has clearances of at least 1 inch (2.5 cm) from the sides and back and 6 inches (16 cm) from the front of the appliance. The opening must directly communicate with the outdoors and must communicate through a vertical or horizontal duct to the outdoors or spaces (crawl or attic) that freely communicate with the outdoors, and must have a minimum free area of a) 1 square inch per 3,000 BTUH (7cm2 per kW) of the total input of all equipment located in the enclosure and b) not less than the sum of the areas of all vent connectors in the confined space.



8 Technical Training Departmen



CONTAMINATED AIR

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, waxes, salts, etc. are drawn into the combustion chamber with the make-up air and, once fired, mix with water vapor in the gases to form extremely corrosive hydrochloric or hydrofluoric acid and other corrosive by-products.

= Rust Chips

AIR FOR COMBUSTION – FLAMMABLE ITEMS






GAS VALVE

The supply gas pressure is normally measured at the gas valve inlet gas pressure tap, if available, when the gas is flowing. The manifold gas pressure is measured at the manifold pressure tap of the gas valve when the gas is flowing. Gas valves used are 24 volt AC combination-step opening gas valves. They incorporate the main valve and gas pressure regulator into one body. The Low Gas Pressure Switch, the Supply Gas Inlet, and the Supply

INLET VIEW TOP VIEW

The top view of the gas valve, shown on the right, shows the Main Gas Regulator, Manifold Pressure Tap, Top Knob, and the Limited

Bleed Vent Port. The main gas regulator is found under the silver cap (silver cap for Natural

Gas or black cap for Propane) screw. It is factory preset to 3.5 inches W.C. and adjusts gas pressure output from 3.0 to 5 inches water column. Caution: Always test the manifold pressure at the outlet when the gas is flowing.



10 Technical Training Departmen



GAS VALVE

The outlet view of the Gas Valve, shown on the right, shows the Manifold Gas Outlet

Connection, the two 24 volt Main Valve (MV) Solenoid connections, and the Manifold

Pressure Tap. The two yellow wires from the 12-pin plug on the Ignition Board attach to the

MV terminals.

OUTLET VIEW






VENTING

All , BTN, and BTR water heaters are classified by ANSI as Category I (non-condensing, negative pressure venting) appliances. They are approved for type B vent. The draft inducer does not pressurize the exhaust.

VENTING – MULTIPLE CATEGORY I GAS WATER HEATERS

For larger applications BTN and

BTR151,201 water heaters can be common vented together, either in a tapered manifold or constant size manifold.

Follow the National Fuel Gas Codes requirements for sizing and installation of fan-assisted products.

,BTN, and BTR 151/201 models may be common vented only with other

Category I appliances.

See the Venting Section in the

National Fuel Gas Code.






VENT TABLES FOR CATEGORY I - TYPE B GAS VENT

Multiple Gas Fired Tank-Type Heaters

When venting multiple Category I tank type heaters using Type B vent pipe, follow the installation tables below which give sizing and data based upon NFPA 54/ANSI Z223.1-2006.

Model: BTN/ 120

I n p u

V e n t

:t 1

C

2 o

0 n

, n

0 e

0 c

0 t o

B t u / h

r S i z e

.r

: 5 ”

No. of Units

2

3

4

Input Btu/hr

120,000

120,000

120,000

Rise

1'

2'

3'

Combined Input (Btu/hr x 1,000)

2 4 0 , 0 0 0

3 6 0 , 0 0 0

4 8 0 , 0 0 0

7

8

9

T o t a l Vent Height (feet)

6 8 1 0 1 5 2 0 3 0 5 0 1 0 0

Vent Connector Diameter (inches)

6 6 5 5 5 5 5

5 5 5 5 5 5 5

5 5 5 5 5 5 5 5

Combined Vent/Manifold Diameter

5

5

7

8

9

6

7

9

6

7

8

6

7

8

6

6

7

6

6

7

6

6

6

Model: BTN 154; BTR 151

I n p u :t 1 5 0 , 0 0 0 / 1 5 4 , 0 0 0 B t u / h

V e n t C o n n e c t o r S i z e : 6 ”

No. of Units

2

3

4

.r

Input Btu/hr

150,000/154,000

150,000/154,000

150,000/154,000

Rise

1'

2'

3'


300,000/ 308,000

450,000/ 462,000

600,000/ 616,000


Ashland City, Tennessee © 2007

13

T otal Vent Height (feet)

6 8 1 0 1 5 2 0 3 0 5 0 1 0 0


6 6 6 6 6 6 6

6 6 6 6 6 6 6

6

6

6 6 6 6 6 6 6 6


7 7 6 6 6 6 6

8 8 7 7 7 6 6

9 9 9 8 8 7 7

6

6

6

Technical Training Department




Model: BTN 180,199, 200; BTR 201

Input: 180,000, 190,000 and 199,000 Btu/hr.

Vent Connector Size: 6”

No. of Units

Input Btu/hr

180,000

190,000

199,000

180,000

190,000

199,000

180,000

190,000

199,000

Rise

1'

1'

1'

2'

2'

2'

3'

3'

3'


2

360,000

380,000

3

398,000

540,000

570,000

597,000

4

720,000

760,000

796,000

Total Vent Height (feet)

6 8 10 15 20 30 50 100


7 7 6 6 6 6 6 6

7 7 7 6 6 6 6

7 7 7 6 6 6 6

6 6 6 6 6 6 6

7 6 6 6 6 6 6

6

6

6

6

7 7 6 6 6 6 6

6 6 6 6 6 6 6

6 6 6 6 6 6 6

6 6 6 6 6 6 6


7 7 6 6 6 6 6 6

6

6

6

6

7 7 7 6 6 6 6

7 7 7 6 6 6 6

6

6

7 6 6 6 6 6 6

7 6 6 6 6 6 6

6 6 6 6 6 6 6

6 6 6 6 6 6 6

6 6 6 6 6 6 6

6 6 6 6 6 6 6

6

6

6

6

6

6







Model: BTN 250

Input:250,000 Btu/hr.

Vent Connector Size: 6”

No. of Units

2

Input Btu/hr

250,000

250,000

250,000

Rise

1'

2'

3'


500,000

3

4

750,000

1,000,000

Total Vent Height (feet)

6 8 10 15 20 30 50 100


8 8 7 7 7 6 6 6

7 7 7 7 6 6 6

7 7 7 7 6 6 6


9 9 9 8 8 7 7 7

6

6

12 12 10 10 10 9 8

14 14 12 12 10 10 9

8

9

Model: BTN 275

I n p u

V e n t

:t 2

C

7 o

5 n

, n

0 e

0 c

0 t o

B t u / h

r S i z e

.r

: 6 ”

No. of Units

2

3

4

Input Btu/hr

275,000

275,000

275,000

Rise

1'

2'

3'


550,000

825,000

1,100,000


6 8 1 0 1 5 2 0 3 0 5 0 1 0 0


8 8 7 7 6 6 6

8 8 7 7 6 6 6

7 7 7 7 6 6 6 6


6

6

10 9 9 8 8 8 7

12 12 12 10 9 9 8

14 14 14 12 12 10 9

7

8

9







Model: BTN 310

I n p u

V e n t

:t 3

C

1 o

0 n

, n

0 e

0 c

0 t o

B t u / h

r S i z e

.r

: 6 ”

No. of Units

2

3

4

Input Btu/hr

310,000

310,000

Rise

1'

2'

310,000 3'


620,000

930,000

1,240,000


6 8 1 0 1 5 2 0 3 0 5 0 1 0 0


9 8 8 8 7 7 6

8 8 8 7 7 7 6

6

6

8 8 8 7 7 7 6


6

10 10 9 9 8 8 7

14 12 12 12 10 9 9

14 14 14 12 12 12 10 9

7

8







Model: BTN 366,400

I n p u :t 3 6 6 , 0 0 0 / 4 0 0 , 0 0 0 B t u / h

V e n t C o n n e c t o r S i z e : 6 ”

.r

Input Btu/hr

366,000

399,000

No. of Units

2

3

4

Rise

1'

366,000

399,000

366,000

399,000

2'

3'


732,000

798,000

1,098,000

1,197,000

1,464,000

1,596,000

T otal Vent Height (feet)

6 8 1 0 1 5 2 0 3 0 5 0 1 0 0


9 9 9 8 8 8 8

10 9 9 9 8 8 8

8

8

9 9 8 8 8 8 8

9 9 9 8 8 8 8

9 8 8 8 8 8 8

9 9 8 8 8 8 8


12 10 10 9 9 9 8 8

12 12 10 10 9 9 8

14 14 14 12 12 10 9

8

9

8

8

8

8

14 14 14 12 12 10 10 9

16 16 14 14 14 12 12 10

16 16 16 14 14 12 12 10






BTN /BTR 151,201 SEQUENCE OF OPERATION

Sequence

1. Thermistors (probes) call for heat.

2. Inducer fan starts and provides draft.

3. Hot surface igniter = 20 sec. warm-up.

4. Main gas valve opens 4 sec. trial for ignition. (Maximum 5 trials.)

5. Main burner ignites and proves.

6. Thermistors reach the temperature setting.

7. Main burners “OFF” - Auto restart after

60 min. - 20 sec blower




BTN, BTR 151/201 TANK TYPE COMMERCIAL


DRAFT PROVING PRESSURE SWITCH - SETTINGS

BTN Models

3 6 6

2 7 5

3 1 0

1 2 0 / 2 0 0

1 5 4 / 1 8 0

Draft Proving Pressure Switch Table

BTR Models

151/201

Pressure Setting

To Close Switch

(Inches W.C.)

-(

-( )

) 1 .

6 0

2 .

0 0

” ±

" ±

. 1 0

. 1 0 "

"

-(

-(

)

) 1

2

,

.

7

4

5

0 "

" ±

± .

. 1

1

0

0

-( ) 2 .

6 0 " ± . 1 0

(-) 2.50" ± .10"

"

"

"

NOTE: Pressure Switch Contacts are Normally Open “N.O.” and close on a fall in pressure.






THERMOSTAT AND IGNITION CONTROL BOARD VIEW






WHITE RODGERS INTEGRATED CONTROL - THERMOSTAT






WHITE RODGERS IGNITION CONTROL BOARD






GAS CONTROL VALVE/BURNER AREA VIEW

Part Number

Volts AC Nominal

Ohms Resistance

HSI

194405

80 VAC

11.0 - 20.0 @ 77° F (25°

C)

NOTICE FLAME ROD CROSSES PATH OF

FLAME .1 - .25”






WIRING DIAGRAM






ELECTRICAL SEQUENCE – BTN / BTR151,201

1. Switch Power on to unit.

2. Thermostat calls for heat.

3. Ignition Control Board performs diagnostic check on system components.

4. On completion of diagnostics check, the Ignition Control Board sends signal to

Exhaust Inducer.

5. Exhaust Inducer begins drawing air through appliance closing the Prover Switch.

6. On completion of Prover Switch engagement, the Ignition Control Board begins the ignition cycle.

7. The Ignition Control Board provides power to the Silicon Nitride Ignitor.

8. The Silicon Nitride Ignitor heats up for approximately 17 to 20 seconds.

9. At the end of Silicon Nitride Ignitor’s warm-up, the Ignition Control Board opens the Gas Valve.

10. From the time the Gas Valve opens, the Ignition Control Board waits 3 seconds and then shuts off power to the Silicon Nitride Ignitor.

11. From the time the Silicon Nitride Ignitor’s power is shut off, the Ignition Control

Board waits 3 more seconds to monitor the Flame Sensor.

12. If the Flame Sensor does not detect a strong enough flame, the Ignition Control

Board shuts off the Gas Valve and allows the Exhaust Inducer to purge the unit for 20 seconds. At that time, the Ignition Control Board restarts with step

7. It will try and ignite the main burners 2 more times. If the unit does not light, the Ignition Control Board will wait one hour and then re-start at step 3. This cycle will continue until the unit lights or the power is shutoff to the unit.

13. If the Flame Sensor detects a strong flame, the Ignition ControlBoard will allow

.

the unit to operate until the thermostat is satisfied.

14. Once the unit is satisfied, the Ignition Control Board will shut off the Gas Valve and the unit will be in standby mode until another call for heat is initiated by the thermostat.






OPERATING SEQUENCE – FLOW CHART






DIAGNOSTIC SEQUENCE OF OPERATION – FLOW CHART






PRE-SERVICE CHECKLIST

Use the following checklist BEFORE you begin servicing the water heater.

1. Have you removed the cover from the controls?

____________________________________________________

Did you take notice of the status lights on the upper water heater control?

____________________________________________________

Did you take notice of the red LED in the upper left corner of the lower ignition control?

____________________________________________________

2.Did you note conditions of the room?

____________________________________________________

Where does the supply air come from?

____________________________________________________

Is the room clean?

____________________________________________________

What is stored with the heater?

____________________________________________________

How is the heater vented?

____________________________________________________

Are all water and gas shut-off valves open?

____________________________________________________

Are there room exhaust or air intake fans?

____________________________________________________

3. Did you note the condition of the heater?

____________________________________________________

Is the ON/OFF switch “On”?

____________________________________________________

What is the temperature of the stored water? (Test at T&P valve or nearby faucet.)

____________________________________________________

Is the thermal expansion tank installed?

____________________________________________________

4. Did you write down the complete model and serial number of the water heater? If so, what are they? ____________________________________________________

5. Does the heater have a good ground wire connection? If not, the inducer will typically come on for a short time (3-5 seconds), then go off, and the red LED will flash 8 times.






HEATER CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND

TROUBLESHOOTING

TEST 1 - 120 VAC CHECK TO HEATER

●

●

●

●

No Green display “Power” LED on.

Plugs are in receptacles.

Supply power breaker is not “open”

On/Off heater switch is “On”.

White Rodgers

Integrated Control

Ignition Control

Board

120 V.

TEST 1

IF.........

voltage is not present from on/off switch center black wire to ground

Power is present from center on/off terminal

Voltage is not present at E13 to ground

Power is present at E13

Voltage is not present from water heater control receptacle

E2 black to ground

Power is present at E2.

120 V. AC check to water heater ON/OFF switch

Check for 115-125 V. AC black wire to ground\

115 V. AC check to E13 Terminal and 2B receptacle.

Then............

Check conditions above

Check wiring from switch to break box

Check power from on/off switch to ignition board terminal

E13 check wiring from on/off. Left-outside terminal to E13.

Replace on/off switch.

Check power from E14 to water heater control E2 receptacle

Check wiring from ignition control board E14 to water heater control receptacle E2.

Replace ignition control board.

Green LED should be on.






IGNITION CONTROL BOARD DIAGNOSTIC LED INTERPRETATION AND

TROUBLESHOOTING

Conditions:

●

●

Power On

Red, heater control “Call for Heat” LED – on

●

●

Red, ignition control board diagnostic LED – Flashing

Note LED Flash Code before resetting heater.

LED Status

1 Flash

2 Flashes

3 Flashes

4 Flashes

5 Flashes

6 Flashes

7 Flashes

8 Flashes

Continuous Flash

Continuous ON

Indication

System is in lock out.

Draft proving (pressure) switch failed to open within 5 seconds at the end of the last cycle.

Draft proving (pressure) switch failed to close ( -2.1 inches of water column pressure) within 5 seconds after the inducer was started. The low gas pressure switch )closes at 5.2" ± .04" w. c.) may have remained open (Nat Gas only.)

Open on high temperature limit switch (ECO).

Not Used

115-volt supply power connection is indicating reversed polarity.

Flame sensor reads a low flame signal for more than 4.25 sec.

No ignition sensed.

Continuous flame sensed for more than 5 seconds without gas valve being energized.

Internal control board failure.

*Control system self adjusts to use a minimum voltage for ignition. Lower voltage results in lower igniter temperature which results in longer igniter life. Igniter voltage may vary from Nominal 80 VAC.






TEST 2 - POLARITY CHECK

Conditions:

●

●

●

●

●

No hot water

Green “Power” LED is on.

Tank is more than 5° F below temperature dial setting.

Red ignition control board diagnostic

LED is flashing 6 times between pauses.

Red, diagnostic “Call for Heat” LED-

OFF.

Display

120 V.

TEST 2

115-125 VAC is not present

Polarity Check

Check from on/off switch center and white wire terminals to ground see Test 1.

Voltage is present white (right terminal) to ground but not black (center terminal) to ground reverse supply wire connections - polarity is reversed.






TEST 3 - CONTINUITY CHECK OF HIGH LIMIT (ECO)

Conditions:

0.0

●

●

●

●

●

●

Power On – No Hot Water

Red, heater control “Call for Heat”

LED – on

Red ignition control board diagnostic LED – 4 Flashing

Note LED Flash Code before resetting water heater control.

See Description of diagnostic LED

Flashes.

Turn Power “Off”

Ohms fI … continuity is indicated (ZERO “0.0” Resistance) continuity

TEST 3 is not present (meter reads “0.L”)

Continuity check of ECO (energy cut-off, high limit)

Black to Black wires of upper probe. Power is off.

t h e n .

..

..

opens at 203° F; closes at 193° F. If water is below 193° F, continuity is correct.

replace ECO sensor, if water temperature is below 193° F.

water is less than 120° F •reset status LED should be on.

•replace heater control if control will not manually reset.






TEST 4 - UPPER TEMPERATURE PROBE CONTINUITY CHECK

Conditions:

●

●

●

Power On - Water below temperature set point.

Red, water heater control “Reset

Status” LED-OFF

Call For Heat” LED off.

Ohms Resistance Table

° F

70°

120°

140°

180°

Ohms

11,884

3,759

2,488

1,169

11,884

Ohms

TEST 4

If…

Test indicates no continuity

Continuity is indicated

Upper Temperature probe continuity check

Red wire to red wire - Turn supply power "Off" for this test then.....

Replace probe.

Probe should be okay (also verify Ohms resistance for water temperature). (Reading will be approximate.)






TEST 5 - CALLING FOR HEAT – NO INDUCER OPERATION

Conditions:

Water Heater Control - Thermostat

●

●

●

●

Power on

Plugs in Receptacles

Red “ Call for Heat” LED-ON

Inducer “Off”

Note flash code on ignition control board diagnostic LED

“call for heat”

LED Indicator

“diagnostic LED indicator”

120

Ignition Control Board fI …

Pin 1 to ground check has no voltage

Pin 1 to ground h a s v o

Pin 3 to ground h a s n o tl a g e v o tl a g e



34 t h e n ..

..

..

..

•reset control by interrupting power - note possible reasons for this from flashing LED code

•replace ignition board

Proceed

•check wiring harness and plugs •replace inducer

Technical Training Department



TEST 6 - INDUCER ON.............NO IGNITION

Conditions:

●

●

●

●

Power on

Plugs in receptacles

Inducer operating

No power to Hot Surface Igniter

(HSI) Note LED flash code

INDUCER

EXHAUST

DRAFT PROVING

PRESSURE

SWITCH

Check E4 pin 2 to ground

HOT WATER

OUTLET

LOW GAS

PRESSURE

SWITCH

TEST 6 24 VAC Check of Blower Prover/Low Gas Pressure Circuit

If… then........

ignition board receptacles E1, Pin 7 to ground shows no voltage replace Ignition board

E1, Pin 7 has 24 Volt to ground voltage check of each blower switch terminal to ground shows

voltage to only 1 terminal check wire connection to and from inducer

Switch is open - check for proper draft (should also see LED 3 flash code)...Check for blocked exhaust.... Check that blower outlet exhaust damper is open....Replace blower (draft) proving switch

Natural Gas ONLY!

24V is present from each switch terminal to ground

Voltage check to each terminal of low gas pressure switch and ground shows only voltage on 1terminal

Check wiring from blower switch to low gas pressure switch

Switch is open - test for a minimum of 5.2 ± " W.C. Natural Gas or

10.5" Propane, flowing supply gas pressure (should also see 3 Flash

LED code)..............Replace low gas pressure switch

Voltage is present to each pressure switch terminal and ground Check wiring from low gas pressure switch to ignition board receptacles E1, Pin 10






TEST 7 - INDUCER ON – PROVER SWITCH AND LOW GAS SWITCH CLOSED

...................NO IGNITER OPERATION

Conditions:

Check E4 pin 4 to Ground

●

●

●

●

●

Power on

Plugs in receptacles

Inducer on

24V at ignition board E1, Pin

10

No Power to igniter

Check E1 pin 10 - 24V

Continuity Test

E4 Plug

Note:LED Flash code

If.......

TEST 7 Voltage check and continuity check of hot surface igniter circuit

Continuity check - Power off- Plug removed from E4 receptacles.

Nominal 80 VAC check - Plug in E4- Power "On".

then.......

Continuity is not indicated between E4plug pin 2 to 4.

Check wiring and connection from E4 plug to HSI receiving plug...................Replace HSI Assembly

Continuity is present

Voltage is not present between E4, Pin 2 to ground

Voltage is present

Voltage is not present between E4, Pin 4 to ground

Voltage is present

Resistance should be between 11 and 20 Ohms at a temperature of 77°F

Replace ignition board

Continue

Check wiring and plug connections to HSI.........Replace HSI

Note ignition board, Flash code LED.............HSI should work






TEST 8 - IGNITER HEATS – NO MAIN BURNER

24 V.

E1 PLUG TO

PIN 9

E1 PLUG TO

PIN 12

TEST 8 IGNITOR HEATS......NO MAIN BURNER

If.......

s hort heat up time of igniter

Normal (Approximate 20 seconds) warm up - no ignition

No voltage present E4, Pin 12 to ground

24 Volt was present from E1, Pin 12 to ground, but no main burner then........

Check control box grounding.

Check for 24V from E1, Pin 12 to ground during 4 second trial.

........Yes - Continue................No - Replace Ignition Board

Replace ignition board

Check that air has been purged from gas circuit........check that wiring and connections to gas valve and E1, Pin 9 are correct

.........check for 24 VAC at E1, Pin 9 to ground during 4 second trial for ignition.






TEST 9 - IGNITER HEATS – NO MAIN BURNER

Conditions:

●

●

●

Test 8 completed then:

Turn off power

Disconnect wires from gas valve

TEST 9

If…

Meter reads 0 or 1

Meter indicates pilot and main coil have continuity

IGNITER HEATS – NO MAIN BURNER then.....

Check meter scale setting to read between 550 and 650 Ohms

R eplace Gas Valve

Valve should be okay....still no gas to main burner, then coil may be stuck .........Replace Gas Valve






TEST 10 - MAIN BURNER IGNITION FOR LESS THAN 5 SECONDS

Conditions:

●

●

Power On – plug connected

Main Burner ignites for approximately 5

●

● seconds then goes out.

Tests 8 and 9 completed

Note flash code on ignition board LED.

Hot Surface Igniter

(Illustration of low NOx burner)

E1, Pin 2 - From Flame Proving Rod

TEST 10

If.......

No extended main burner ignition

Still no extended main burner ignition

MAIN BURNER IGNITION FOR LESS THAN 5 SECONDS then.........

Check wiring and plug connections of HSI assembly plug and ignition board receptacles E1, Pin 2.......Check that HSI assembly is not cracked or dirty......Check that flame prover will be in main flame ......................Replace HSI assembly

Replace ignition control board






TEST 11 - WATER HEATER SHUTTING OFF BELOW SETTING

Conditions:

●

●

Main burner ignited

Stored water is below temperature setting more than 5° F (Tank

●

●

Average).

Power off

Plug disconnected from heater control board receptacle E3 and E4

TEST 11 WATER HEATER SHUTTING OFF BELOW SETTING

(Water Temperature Circuit Check - Continuity)

Continuity check pin to pin of lower temperature probe shows 1 or 0 (E4)

See Test 4.....

Check wiring and plug connections to heater control board receptacle E4

Replace lower temperature probe

Continuity check red wire pin to red wire pin on upper temperature sensor shows 1 or 0 (E3)

All above checks are okay

See Test 4.......

Check wiring and plug connections to heater control board receptacle...........Replace upper temperature probe

Check wiring and plug connections to heater control board receptacle...........Replace upper temperature probe.






DISPLAY LIGHTS ON INTEGRATED HEATER CONTROL

LED

STATUS

I N D I C A T I O N

Calling for heat

A C T I O N

The ECO (Energy Cut-Off) has opened.

Normal status – none

•Check for excessively hot water

.........(203° F or higher).

•Correct the problem

No power Check the breaker.

Tank is at a set temperature of ..............± 2° F.

Tank has cooled below 120° F

Preceded by “ECO Open” indication

No Action Required

•Push the manual reset button.

•Troubleshoot for“why” the ECO opened














































GENERAL QUESTIONS AND ANSWERS

Q: What is the effect of the draft inducer?

A: The draft inducer has several effects:

• minimizes the excess air through the heater—this often reduces the required vent size

• reduces draft through the heater when it is off

• replaces the draft hood of comparable products

• does not pressurize the vent—common “B” vent materials and the familiar fuel gas codes for venting Category I, fan-assisted, products still apply. Do not combine vent with products that do create a positive pressure vent (Category III or IV).

Q: What is the significance of low NOx (nitrogen oxide)? (BTN Models)

A: Currently, only Southern California and Texas have adopted rules to reduce the Nox emissions under Rules 1121 and 1146.2, but more of California and Texas are expected to implement this requirement in 2001. Ground-level ozone from man-made pollution is a major ingredient in smog. NOx is a contributor to this ground-level ozone formation. The boilers and water heaters affected by Rule 1121 and 1146.2 release about 14 tons of NOx emissions into the air each day. By comparison, approximately the same quantity of NOx is emitted by

288,000 typical passenger vehicles daily. It is estimated that a full implementation of this emissions rule will reduce NOx by about 11 tons daily. These emission requirements are expected to be implemented by other cities and states soon. The rules apply to natural gas water heaters and boilers.

Q: When should anode rods, which provide additional protection against corrosion, be replaced?

A: Anode rods should be replaced when large gouges or pits appear in the anodes. It is recommended that anodes be inspected every six months.

Q: Does the inducer motor require oiling?

A: No.

Q: What size breaker should be used?

A: The heater should draw less then 5 amps and there is a 3-amp car-type fuse on the control board. This fuse protects the boards.




Visit the “Information Central” link of www.hotwater.com for a listing of available Service Handbooks.

For additional information contact:

A. O. Smith Water Heaters

500 Tennessee Waltz Parkway

Ashland City, TN 37015

1-800-527-1953 www.hotwater.com

©2007 A. O. Smith Corporation

Part No. 317923-000

A.O. Smith BTC 201 Installation manual

Induced Draft Multi-Flue

Commercial Water Heaters

Table of Contents

User-Defined Index

Feet

Com. Air

2.5 Cubic

Feet

Excess

Air

= Rust Chips

Sequence

Calling for heat

The ECO (Energy Cut-Off) has opened.

Normal status – none

•Check for excessively hot water

.........(203° F or higher).

•Correct the problem

No power Check the breaker.

Tank is at a set temperature of ..............± 2° F.

Tank has cooled below 120° F

Preceded by “ECO Open” indication

No Action Required

•Push the manual reset button.

•Troubleshoot for“why” the ECO opened

Visit the “Information Central” link of www.hotwater.com for a listing of available Service Handbooks.

For additional information contact:

1-800-527-1953 www.hotwater.com

Related manuals

Table of contents

A.O. Smith BTC 201 Installation manual

Induced Draft Multi-Flue

Commercial Water Heaters

Table of Contents

User-Defined Index

Feet

Com. Air

2.5 Cubic

Feet

Excess

Air

= Rust Chips

Sequence

Calling for heat

The ECO (Energy Cut-Off) has opened.

Normal status – none

•Check for excessively hot water

.........(203° F or higher).

•Correct the problem

No power Check the breaker.

Tank is at a set temperature of ..............± 2° F.

Tank has cooled below 120° F

Preceded by “ECO Open” indication

No Action Required

•Push the manual reset button.

•Troubleshoot for“why” the ECO opened

Visit the “Information Central” link of www.hotwater.com for a listing of available Service Handbooks.

For additional information contact:

1-800-527-1953 www.hotwater.com

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Table of contents