AO Smith Water Heater 120 trough 500 User Manual

BTR TANK TYPE HEATERS

SERVICE HANDBOOK

BTR HANDBOOK

TABLE OF CONTENTS

PAGE

Troubleshooting (continued)

1-2

Troubleshooting the Efflkal

Wire Harness Test

IID Module

30-31

Introduction

Installation

Clearances

3-4

5-9

Pilot Spark

Pilot Valve

Main Burner Test

Flame Rectification

IID Module

35-36

Air Requirements

Contaminated Air

Flammable

Gas Pressure

Gas Valve

Main Gas Valve 40-41

Venting

13-15

Wiring Schematics

Natural and Propane Gas

Sequence of Operation

Mechanical

Service Charts

Electrical

17-18

General Questions & Answers

Parts List

Troubleshooting

Transformer

20-21

22-23

45-50

High Limit

Damper (on Standby)

PC Board

Thermostat

Damper (call for heat) 25-26

Component Part Information

Service Check List

Comments

52-53

Effikal Damper

Effikal Harness Test

Normal Operation

28-29

BTR WORKBOOK INTRODUCTION

This service handbook is designed to aid in servicing and troubleshooting A.O. Smith BTR water heaters in

the field. 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 common questions encountered in the

operation of the BTR 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

installation manual accompanying the product. This handbook contains supplemental information to the BTR

installation and operation manual.

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Installation or service of this water heater requires ability equivalent to

Qualifications:

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

a 3/8 and 7/16 inch open end wrench

set of marked drill bits

an electrical multimeter tester capable of measuring continuity

gas pressure gauge or manometer (gauge - AOS pt. no. 8099-2)

water pressure gauge (AOS pt. no. 4798)

thermometer (AOS pt no. 4870 - range 0 - 220 degree F)

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

1 1/16 inch socket with extension for anode removal.

•

MISC: TC-043 Revision 1 vs. TC-043

Revision 1:

Adds Additional model’s information.

•

Adds cover statement this Handbook’s also a Service Handbook for many BTC Models.

Includes Power vent kit information.

•

Includes BTR/C-500 gas valve information.

Updated Damper illustrations.

•

Revision2:

Revised Part Numbers on Page 15

•

Revision 3:

Adds information unique to the Efflkal damper equipped (Series 110, 111 and

Retrofit) models

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INSTALLATION

This portion of the handbook will review some often overlooked installation

considerations, taking note of necessary installation requirements for the BTR 120

through 500 model heaters. The installation manual covers most of these items in detail.

CLEARANCES FROM COMBUSTIBLES

Clearance to Combustibles Table

MODEL

120 - 200

250 - 305

365 - 500

1” (2.54CM)

2” (5.08CM)

3” (7.75CM)

1” (2.54CM)

2” (5.08CM)

3” (7.75CM)

1” (2.54CM)

2” (5.08CM)

3” (7.75CM)

A 24 inch clearance for all serviceable parts is recommended. Clearances may vary

between BTR models – See instruction manual or the label on the heater, for clearances

applicable to your specific model.

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EXTERIOR CLEARANCE

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

This illustrates the exterior roof clearances for BTR units with natural draft venting. The

vent shall 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" in diameter or less). (NFPA 54 ANSI Z 223.1 SEC

7.5.2a). (Sec 7.6.2a may allow reduction to 8 feet with a “ Listed vent cap”).

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AIR FOR COMBUSTION

10 CUBIC FEET OF AIR PER 1,000 BTU

10 CU.

FT.

COMB.

AIR

1,000

BTU

2.5 CU.

FT.

EXCESS

AIR

Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1000

BTUH input of the 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 models.

The National Fuel Gas Code also specifies minimum make-up air opening sizes for

various building installations. (Ref: NFPA 54, ANSI Z223.1, sec 5.3)

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MAKE-UP AIR

DIRECT COMMUNICATION

1 Square

Inch Per

4,000

BTUH

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 out of doors. Two openings are

required - one within 12 inches of the top of the enclosure and one within twelve 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 dilution air and acts as a relief 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,

commencing within 12 in. (30 cm) of the top of the enclosure, shall be permitted where

the equipment has clearances of at least 1 in. (2.5 cm) from the sides and back and 6 in.

(16 cm) from the front of the appliance. The opening shall directly communicate with the

outdoors and shall communicate through a vertical or horizontal duct to the outdoors or

spaces (crawl or attic) that freely communicate with the outdoors, and shall have a

minimum free area of:

a. 1 sq. in. per 3000 BTU per hr (7 cm²per 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.

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MAKE-UP AIR

VERTICAL DUCTS

1 Square

Inch Per

4,000

BTUH

Often it is more practical to install vertical make-up air ducts to the out doors. Again, two

openings are required - one within 12 inches of the top of the enclosure and one within

twelve 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.

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MAKE-UP AIR

HORIZONTAL DUCTS

1 Square

Inch Per

2,000

Daily Schedule

BTUH

When the heater is installed in an interior room with no roof access for vertical ducts,

horizontal make-up air ducts should be installed. When using horizontal ducts, two

openings are required - one within 12 inches of the top of the enclosure and one within

twelve inches 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.

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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 shut down.

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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 byproducts.

AIR FOR COMBUSTION

Flammable Items

Flammable items, 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.

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GAS PRESSURE REQUIREMENTS

Supply Gas

Manifold

Pressure

Tap

Dirt Leg

Manifold

Gas Port

Natural Gas

Propane Gas

Maximum Supply Pressure

13.8" w.c.

4.5" w.c.

3.5 " w.c.

13.8" w.c.

11" w.c.

10" w.c.

Minimum Supply Pressure

Manifold Pressure

The supply gas pressure is normally measured at the dirt leg or at the gas pressure

tapping on the gas supply shutoff valve. This reading must be measured with 'flowing'

gas.

The manifold gas pressure is measured at the manifold pressure tap of the gas valve

when the gas is flowing.

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BTR GAS VALVE

The gas valves used on all BTR water heaters are

24 volt AC combination step opening gas valves.

They incorporate the pilot valve, main valve, and gas

pressure regulators into one body. The inlet view of

the valve features a filter screen and the top knob.

The top knob is a manual on/off gas control for both

the pilot and main gas valves. When the top knob is

placed on the black mark, gas is supplied only to the

pilot valve.

On the top view, we see the pilot solenoid and

pilot and main gas regulators. The top view also

displays the “TH and “TR” terminals. The pilot

gas regulator is found under its cover screw. It is

factory preset at 3.5”w.c. but can be adjusted from

2.5 to 5 inches water column. The main gas

regulator is found under its cover screw. It is

factory preset to 3.5 inches w.c. and adjusts gas

pressure output from 2.5 to 5 inches water

column. The two electrical terminals are marked

TH and TR. The TH terminal is the common

between the pilot valve solenoid coil and the main

valve solenoid coil. The other wire emerging from

the pilot solenoid connects to the pilot valve

electrical output on the IID (terminal PV). The TR

terminal connects directly to the main valve

electrical output from the IID module

(terminal MV).

On the outlet view of the gas valve, we see the

pilot gas connection port, manifold gas connection

port, a limited bleed vent port, the manifold gas and

pressure tap.

See step 18 for BTR-500 gas valve illustration

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VENTING

Atmospheric Multiple Heaters

Chimney

A minimum of ¼” rise

per foot of horizontal

vent is required.

All BTR water heaters are classified by ANSI as category I (non-condensing, negative

pressure venting) appliances. They are approved for type B vent.

For larger applications, BTR water heaters can be common vented together either in a

tapered manifold or constant size manifold. (Follow National Fuel Gas Code

requirements for sizing and installation.)

BTRs may be common vented only with other category I appliances. (See venting

section in the National Fuel Gas Code).

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DRAFT INDUCER

Draft inducers can be used with BTR water heaters to mechanically aid a lazy chimney in

vertical vent applications. They are not designed to allow “through-the-wall” vent

installations. (See Power Venter)

SINGLE UNIT INSTALLATION

When mechanically venting, the following items are required:

Qty

Description

Draft Inducer (up to 300,000Btuh)

Draft Inducer (up to 305,000 thru 500,000 Btuh)

Draft Prover Switch

Part No.

90909

90910

95220

96695

Relay Switch

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POWER VENT KITS FOR SIDEWALL VENTING

Female plug

to Damper

40’, Power Venter

cable with “Y”

connect

Male plug

to Cable

Water Heater Models

BTR-120-200

Part Number

193933-0

BTR-250-500

193933-1

BTR water heaters can be used

with power vent kits for sidewall

venting. A.O. Smith offers power

vent kits for use on installations with

a maximum of 100 equivalent feet

of vent piping. The power vent kits

also use type B vent materials.

When power venting, specific

exterior clearances must be

maintained, as outlined in the

National Fuel Gas Code. (NFPA

54, ANSI A223.1, sec 7.8)

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BTR SEQUENCE OF OPERATION

9. Flue damper closes

2. Flue damper opens

1. Thermostat calls for heat

7. Thermostat satisfies

4. Pilot gas opens,

Pilot sparks and

flame proves

3. Intermittent

Ignition Control

6. Main burner ignites

5. Main gas valve opens

8. Main and pilot

burners "OFF"

SEQUENCE OF OPERATION

To understand BTR tank type water heaters, an examination of their sequence of

operation is necessary.

When the thermostat calls for heat, the relay in the draft hood assembly activates, de-

energizing the flue damper motor. The damper opens and power flows to the IID

(Intermittent Ignition Device). This activates the IID module to open the pilot valve

and begin sparking at the pilot burner assembly. Once the pilot flame is established

and confirmed back to the IID, the sparking is stopped and the main gas valve is

opened, allowing gas flow to the main burner. When the thermostat satisfie’s, main

and pilot gas is shut off.

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BTR ELECTRICAL SEQUENCE

100 – 109 Series

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BTR ELECTRICAL SEQUENCE OF OPERATION

1 2 0 V ac to Ju n ction B ox

O n / O FF S witch "O N "

2 4 V Tran sform er

Tan k Tem p eratu re

H ig h L im it C losed

Th erm ostat C losed

Tan k Tem p eratu re

S atisfied

H ig h L im it (E C O )

C losed

M otor C loses

D am p er

S eries 1 1 0 an d 1 1 1

E ffikal

M otor R elay In terru p ts

P ower to M otor

M otor O p en s

D am p er

D am p er S p rin g O p en s

D am p er B lad e

C am O n D am p er B lad e

C loses P rovin g E n d S witch

IID M od u le

(2 4 V ) R eceives V oltag e

M od u le (P V ) Tem in al

S en d s 2 4 V to P ilot C oil

M od u le (S p ark) S en d s

1 0 ,0 0 0 V S p ark to P ilot

P ilot Ig n ites an d P roves F lam e

S p ark S top s

M od u le (M V )

Term in al S en d s 2 4 V

To M ain G as C oil

9 0 S econ d Trial /

5 M in u te D elay B etween

Trials - C on tin u ou sly

M ain B u rn er H eats Tan k

Th em ostat O p en s

S eries 1 1 0 an d 1 1 1

E ffikal

P ower to D am p er

R elay (4 ) In teru p ted

P ower to D am p er

# 2 In terru p ted

D am p er M otor E n erg ized

an d D am p er C losed

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TROUBLESHOOTING BTR WATER HEATERS

To troubleshoot a BTR water heater check that:

120 VAC is supplied to the heater

the tank is full of water

gas is supplied to the unit

•

STEP 1

TEST THE TRANSFORMER

- Using a multimeter, test for 24 VAC

between the secondary transformer terminals.

STEP 1 - TO TEST THE TRANSFORMER

THEN

The meter does not read 24 VAC:

Check that the 120 VAC is supplied

from the On/Off Switch – if not, replace

switch.

•

Check that the 120 VAC is supplied

from transformer.

Go to step 2.

•

The meter reads 24 VAC:

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STEP 2

HIGH LIMIT, LEFT TERMINAL TEST

Test for 24 VAC between the left high

STEP 2. HIGH LIMIT, LEFT TERMINAL TEST.

limit terminal and ground.

THEN

The meter does not read 24 VAC:

Check wiring between transformer and

high limit.

•

The meter reads 24 VAC:

Go to Step 3.

•

Note: The high limit (Energy Cut Off) opens if the tank water temperature exceeds 205

degrees. The control is resettable (manually) when the tank water temperature drops

below 185 degrees.

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STEP 3

TEST HIGH LIMIT RIGHT TERMINAL

. Ensure that the jumper wire

STEP 3. TO TEST HIGH LIMIT RIGHT TERMINAL

between the high limit and thermostat is connected, and the damper motor power line is

connected. Test for 24 VAC between the high limit right terminal and ground.

THEN

The meter does not read 24 VAC:

Push the reset button and redo the test (storage

•

water temperature below 185 degrees).

The meter reads 24 VAC:

Go to step 4.

•

After Push in Reset - 24 VAC is now present

Reasons For Resetting

Cause

Condition

High limit open

Solution

Never set on initial

installation

Faulty thermostat

Push high limit button

Replace dual control

Excessive water temperature

Heater shut down before

reaching thermostat setting

Faulty high limit

Note: The right terminal of the high limit has a jumper wire connected to the left terminal of the

thermostat. There is also a black wire connecting to the damper motor assembly. This black wire

supplies power to the motor to close the damper during periods of standby.

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STEP 4

INSPECT THE DAMPER

Effikal Damper Open

Lower the thermostat setting so the unit will not be

calling for heat, then inspect the damper.

STEP 4. INSPECT THE DAMPER.

THEN

If the damper is open:

If the damper is closed:

Note: If the water temperature in the tank is below 120 degrees F, temporarily disconnect the

jumper wire between the high limit and thermostat to simulate a satisfied thermostat.

Go to step 5.

•

Go to step 7.

STEP 5

CHECK THE PC BOARD

Test for 24 VAC between the black PC board wire

STEP 5. CHECK THE PC BOARD.

connection and ground.

THEN

24 VAC is not present:

Check the black wire connections

between PC Board and high limit.

Go to step 6.

•

24 VAC is present:

•

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STEP 6

PC BOARD MOTOR TEST

Motor Lead

Terminals

Service Switch

Check for 24 VAC between the two motor lead

terminals of the PC board. Disconnect the wires for this test.

STEP 6. PC BOARD/MOTOR TEST.

THEN

24 VAC is not present:

Replace the board (AOS part # 6522)

•

and go to step 7. The board and relay

are one piece. Regardless of which

part is defective, both parts should be

changed.

Voltage is present:

•

This verifies that the motor is receiving

power but not closing the damper.

Replace the motor (AOS part # 6521)

and go to step 7.

Note: The service switch may be used to bypass the damper, while waiting for a replacement part.

In the event of damper motor failure, verify that the damper is in the "open"

WARNING -

position before utilizing the service switch. (BTR Series 106/107 and some prior series –

changed from momentary push button to service switch).

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STEP 7

THERMOSTAT TEST

Set the thermostat to call for heat. Using your

multimeter, test for 24 VAC between right terminal and ground.

STEP 7. THERMOSTAT TEST.

THEN

The meter does not read 24 VAC and the jumper wire

between the high limit and the thermostat is in place:

The meter reads 24 VAC:

Replace the thermostat

•

Go to step 8.

•

Note: If the high limit to thermostat jumper wire was disconnected earlier to simulate a satisfied

thermostat, reconnect the jumper to the terminals.

Note: A yellow wire from this thermostat terminal connects to the damper PC board.

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GO TO PAGE 27 FOR DAMPER TESTS OF EFFIKAL EQUIPPED (SERIES 110, 111 AND

RETROFIT) MODELS

STEP 8

DAMPER INPUT TEST

Test from

Orange

wire to

Black

(neutral)

Test for 24 VAC between the yellow wire on the PC

board and ground. Effikal – Check from orange wire to neutral

STEP 8. DAMPER INPUT TEST.

THEN

24 VAC is not present:

Check the black wire connections

•

between the PC board and high limit.

24 VAC is present

Go to step 6.

•

STEP 9

TEST THE DAMPER

. Visually check the damper blade position.

STEP 9. TEST THE DAMPER

THEN

The damper does NOT open fully:

The damper DOES open fully:

Replace the damper assembly

•

Go to step 10.

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STEP 10

TEST DAMPER OUTPUT

On a call for heat, the damper relays receives

STEP 10. TEST DAMPER OUTPUT.

power through the yellow wire and power to the motor is interrupted. Then, the motor

clutch is disengaged and the damper opens. The damper proves it is open via an end

switch before power flows through the red wire from the PC board.

Place the red test probe on the solder joint of the red wire connection to the damper PC

board.

THEN

The meter does not read 24 VAC and the

end switch is closed:

Replace the PC board

•

The meter reads 24 VAC

Go to step 11.

•

Note: The spring rotates the damper blade assembly to the open position. This closes an end

switch.

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EFFIKAL DAMPER

BTR Series 110 and 111 began using the motor open; motor close, Effikal Damper. The

wiring colors from the damper PC Board are different from previous series BTR(C) and

BTC Models.

Motor

Lead

Service

Switch

Service

Switch

Adapter

Plug

Motor

Lead

Terminal

Motor

Heater

Harness

Effikal Control Cover (Photo of kit mounting)

Effikal Style

The heater harness wires still serve the same function:

Damper

Black – 24V Constant if high limit closed

Yellow – 24V To damper if the thermostat is closed

Red – 24V From damper to IID if damper closes end switch

White – Neutral (common)

Orange Brown Yellow Black

From Heater

Male Plug

Female Plug

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HARNESS CHART

Heater Harness

Black

Yellow

Red

Function

24V Hot

24V from Therm

24V from damper

24V common

Damper Harness

1-Brown

2-Orange

3-Yellow

4-Black

White

Series 110 and 111 heaters and converted model BTR(C) and BTC heaters with Effikal

Dampers.

NORMAL OPERATION

Condition:

Heater on standby

Damper closed

High Limit closed

•

Wires are from left to right:

Black

Yellow

Brown

White

TEST FOR 24VAC BETWEEN BLACK (COMMON)

AND BROWN

STEP A

STEP A. TEST FOR 24VAC BETWEEN BLACK (COMMON) AND BROWN

THEN

Continue to Step B.

24VAC is present

24VAC is not present

See Troubleshooting Step A1

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NORMAL OPERATION (continued)

Condition:

Thermostat closed, damper in process of opening

•

STEP B

TEST FOR 24VAC BETWEEN BLACK AND ORANGE

THEN

Continue to Step C.

24VAC is present

24VAC is not present

See Troubleshooting Step A2

Condition:

Thermostat closed, damper fully open

•

STEP C

TEST FOR 24VAC BETWEEN BLACK AND YELLOW

THEN

Continue to Step 11

24VAC is present

24VAC is not present

See Troubleshooting Step A3

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TROUBLESHOOTING THE EFFIKAL STYLE DAMPER

Condition:

Thermostat closed, damper

Wires are from left to right:

Black

Yellow

Brown

White

TEST BETWEEN BLACK (COMMON) AND BROWN

ON THE DAMPER BOARD

STEP A1

THEN

This is correct

24VAC is present

24VAC is not present

See Steps 1 thru 4

•

Check the harness plugs connecting heater

and damper for looseness or damage.

Condition:

Thermostat closed, damper in process of opening.

STEP A2

TEST FOR 24VAC BETWEEN BLACK AND ORANGE

THEN

This is correct

24VAC is present

24VAC is not present

See Step 7

Check the harness plug connecting

heater ----or damaged

•

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TROUBLESHOOTING THE EFFIKAL STYLE DAMPER (continued)

Condition:

Thermostat closed, damper is open fully

STEP A3

TEST FOR 24VAC BETWEEN BLACK AND YELLOW

THEN

24VAC is present

This is correct – continue to Step 11

24VAC is not present

See Step 9

•

Check the harness plug connecting ----

Check that cam on shaft rotates with

shaft

Replace the damper board

•

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STEP 11

WIRE HARNESS TEST

Test for 24 VAC between terminal 24V on the IID

STEP 11. WIRE HARNESS TEST.

module, and 24V (GND).

THEN

24 VAC is not present:

24 VAC is present:

Check the wiring harness.

•

Go to step 12.

Note: This test may be easier to conduct by removing the red wire from the IID terminal. Test for 24

VAC between the red wire and ground. Reconnect the red wire to the 24V terminal after the test.

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STEP 12

IID MODULE TEST

Using a multimeter, test for

STEP 12. IID MODULE TEST (Power to the Pilot Valve).

24 VAC between terminal PV and 24V (GND) on the IID during the 90 second trial for

ignition.

THEN

The meter does not read 24 VAC and the

IID module is not between ignition trials:

The meter does read 24 VAC:

Replace the module.

•

Go to step 13

•

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STEP 13

PILOT SPARK TEST

Visually check for spark at the pilot assembly.

Note: The pilot burner mounts on the left side of the main burner.

STEP 13. PILOT SPARK TEST.

THEN

Check for:

The igniter is not sparking:

A 7/64” spark gap

•

Spark cable continuity

Ground cable continuity

Go to step 14.

Sparking is present:

Power To Module May Be Interrupted To Reset .

Trial for Ignition

90 sec.

5 min.

90 sec.

5 min.

90 sec.

Continuous

Sparking Trial

Sequence

Call for

heat

Sparking No

Sparking

Sparking No

Sparking

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STEP 14A

PILOT VALVE - OHM TEST

BTR 120 – 400 GAS VALVE

If pilot assembly is sparking but no pilot flame

STEP 14A. PILOT VALVE - OHM TEST.

is established, disconnect the pilot valve solenoid leads. Using a multimeter, (set to read

ohms) test for 20* ohms resistance +/- 5 through the solenoid coil.

THEN

The meter dose not read 20 ohms plus or

minus 5:

Replace gas valve

•

The meter does read 20 ohms plus or

minus 5:

Gas valve should work. Also check that

pilot gas is present and pilot tube or

orifice are not blocked

•

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STEP 14B

PILOT VALVE TEST – BTR 500 ONLY

PILOT GAS

MANIFOLD

PRESSURE

TAP

BLUE

WHITE

RED

The MV/PV wire on the IID is connected to the white wire

The MV wire on the IID is connected to the red wire.

MANIFOLD

GAS

MANIFOLD

PRESSURE

TAP

Testing the two coils of the

STEP 14B. PILOT VALVE TEST – BTR 500 ONLY.

Honeywell VR8404P 5004 gas valve used on the model BTR 500 only. Because of built

in diodes, it is difficult to test for ohms resistance through these coils. The following is a

DC amperage check of the main and pilot coils.

Condition:

•

Tank calls for heat

PV terminal of module has 24 Vac

No Pilot flame

Test Procedure:

•

Turn off power to heater

•

Meter set to test for DC amperage (on AOS meters, the black wire is in the

“com” port, the red wire is in the “10A” port, the dial is set to 20M/10A in the DC

AMP test area).

•

Blue “PV” wire is disconnected from the ignition PV terminal.

Install meter in series between gas valve and ignition module – 10A wire to

blue gas valve lead, common wire to PV module terminal.

Turn power on to heater, after module receives 24V

•

Test DC Amperage through Pilot coil of gas valve

THEN

.75 to .85 DCA is not present:

.75 to .85 DCA is present

Power off, reattach blue gas valve wire to PV terminal of module.

Replace the gas valve

•

Pilot should work if gas (not air) is present to pilot

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STEP 15

MAIN BURNER TEST

Note: BTR series 108 and 109 implemented a new main burner stamping process –

burners appear the same as illustrated.

Visually check for main burner.

STEP 15. MAIN BURNER TEST.

THEN

The main burner ignites:

The main burner does not ignite

Sequence is complete

•

Go to step 16

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STEP 16

FLAME RECTIFICATION

STEP 16. FLAME RECTIFICATION

Note: Flame rectification means that an alternating current (AC) signal is changed to a direct current (DC)

signal. The pilot flame is the 'switch' which connects the pilot hood to the igniter and ground. If the pilot

hood and igniter sensor had the same surface area, the flame 'switch' would conduct an AC signal.

Because the pilot surface is greater than the igniter surface, the signal becomes a DC current that the

module can interpret. The pilot hood must be properly grounded and the pilot flame must remain in

contact with both surfaces for the flame proving signal to remain constant.

If the signal is broken for just 8 tenths of a second, the heater will cycle off.

Sparking at the pilot will continue if an insufficient signal is received by the module.

Sparking at the pilot will stop almost immediately after the ignition module senses the pilot flame.

THEN

Sparking continues after pilot is

established:

Check wire connections

•

Check flame contact between hood

and lighter

•

Clean pilot burner surfaces

Replace pilot assembly

Go to step 17.

•

Sparking stops:

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STEP 17

IID MODULE TEST

Pilot is lit - Sparking has stopped.

Using a multimeter, test for

STEP 17. IID MODULE TEST (Power to the Main Valve).

24 VAC between terminal MV on the IID and 24V (GND).

THEN

24 VAC is not present:

Replace the IID module. Conduct Step

18 before applying power to

replacement module.

•

24 VAC is present:

Go to step 18.

•

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STEP 18A

MAIN GAS VALVE CHECK

BTR 120 – 400 GAS VALVE

Disconnect wires from gas valve TH and TR

STEP 18A. MAIN GAS VALVE CHECK.

terminals. Using a multimeter, test for 68 ohms plus or minus 5 between TH and TR on

the main valve coil.

THEN

The meter reads ‘O’ or infinity

The meter reads 68* ohms plus or minus 5

Replace the gas valve

•

The main burner will ignite

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STEP 18B

MAIN GAS VALVE COIL CHECK

PILOT GAS

MANIFOLD

PRESSURE

TAP

BLUE

WHITE

The PV wire is connected to the blue wire

RED

The MV/PV wire on the IID is connected to the white wire.

The MV wire is disconnected from the gas valve.

MANIFOLD

GAS

MANIFOLD

PRESSURE

TAP

STEP 18B. MAIN GAS VALVE COIL CHECK – BTR 500 ONLY

Condition:

•

Pilot lights

Sparking stops

No main burner ignition

Test Procedure:

•

Power off

Disconnect red, main valve wire from module MV terminal

Meter set to test for DC amperage

10A wire to red gas valve wire, COM wire to MV terminal of ignition module

Turn power on to heater

After pilot lights and sparking stops

IF:

THEN:

.25 to .35 DC Amps is not present

.25 to .35DCA is present

Replace the gas valve

•

Main burner gas should ignite.

Be certain to correct you meter wire connections and setting before performing further

tests.

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BTR WIRING DIAGRAM - NATURAL AND PROPANE GAS

Honeywell Ignition System (110 – 109 Series)

IF ANY OF THE ORIGINAL WIRE AS SUPPLIED MUST BE

REPLACED, USE ONLY TYPE 105° C THERMOPLASTIC OR

EQUIVALENT.

BLUE

WHITE

MV/

RED

GAS VALVE FOR

BTR-500/A ONLY

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GENERAL SERVICE CHART

CONDITION

DAMPER OPENS NO POWER

TO IID MODULE

CAUSE

SOLUTION

.EFFIKAL – REPLACE DAMPER CONTROL

ASSEMBLY

. DAMPER NOT FULLY OPEN

. REPLACE DAMPER

. DEFECTIVE PROTECTOR

SWITCH

. REPLACE PC BOARD

PILOT LIGHTS, SPARKS

CONTINUOUSLY

PILOT FLAME NOT PROVING

SEE FLAME RECTIFICATION - STEP 16

INTERRUPT 120 VAC POWER

NOT PROVING PILOT

FLAME EXISTANCE

. CHECK GROUND WIRE

ATTACHMENT

HEATER WILL NOT IGNITE

. CLEAN OR REPLACE PILOT

ASSEMBLY

PILOT GAS NOT COMPLETELY

INTERRUPTED AT END OF

HEATING CYCLE

. CHECK SUPPLY GAS PRESSURE

. REPLACE GAS VALVE

WEEPING TEMPERATURE

AND

PRESSURE RELIEF VALVE

. THERMAL EXPANSION

. FAULTY VALVE

ADD THERMAL EXPANSION TANK

REPLACE RELIEF VALVE

LARGE VOLUME WATER

RELIEF FROM T&P VALVE

. EXCESSIVE WATER

TEMPERATURE

. FAULTY RELIEF VALVE

. CHECK WIRING

. REPLACE DUAL CONTROLLER

REPLACE RELIEF VALVE

PREMATURE TANK

LEAKAGE

CONDENSATION

. INCREASE STORED WATER

TEMPERATURE AND CONFIRM

PROPERLY SIZED APPLICATION

CONTAMINATED AIR

WATER HAMMER

. REMOVE CONTAMINANTS.

. SUPPLY CLEAN COMBUSTION

AIR.

. ADD WATER HAMMER

ARRESTOR.

. REDUCE WATER PRESSURE.

. REMOVE UNNECESSARY CHECK

VALVES.

THERMAL EXPANSION

DEPLETED ANODES

ADD THERMAL EXPANSION TANK.

SCHEDULE ANODE CHECKS -

REPLACE AS NEEDED.

DAMPER WILL NOT OPEN

BINDING SHAFT

SUPPORT VENTING

SHAFT SPRING WEAK/BROKEN

DAMPER MOTOR

REPLACE DAMPER NON-EFFIKALS

REPLACE MOTOR EFFIKAL-REPLACE DAMPER

CONTROL ASSEMBLY

NO SPARK AT PILOT -

DAMPER FULLY OPEN

DAMPER ASSEMBLY

REPLACE PC BOARD - SEE STEP 10

Services Switch may bypass problem until

replacement part is received. (EFFIKAL –

REPLACE DAMPER CONTROL ASSEMBLY

REPLACE IID STEP 12

IID MODULE

SPARK CABLE

REPLACE CABLE STEP 13

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GENERAL QUESTIONS AND ANSWERS

What changes caused series 106/107 and 108/109 to be implemented?

The 106 and 107 series units changed from the momentary push button to a slide

switch. The 108 and 109 series implemented a new main burner construction process. The

damper boards with service switch and new style main burners will automatically be

replacement parts for previous series heaters if parts are ordered.

What is unique about the Canadian – BTRC – models vs. U.S. BTR models?

A. The Canadian models have different dimensions to meet Canadian code requirements.

How much electrical power is required for a BTR water heater?

A: The BTR models draw approximately .7 Amps at 120VAC.

The units require "leg kits" to meet National Sanitation Foundation standards. What are the

part numbers for these kits?

The BTR model heaters need AOS kit numbers:

BTR 120-400 (except BTR 197&198 series 100) = Part # 6570-0

BTR 197&198 Series 100 = Part # 6570-5

BTR 500 = Part # 6570-7

When should BTRs be delimed?

Many variables affect the liming up process including:

- The amount of lime accumulation during the same period of time will be

water temperature

nearly 2 times greater if water is stored at 140 degrees F than at 120 degrees F. A 180

degree setting will build up lime about seven times as fast as a 140 degree F setting.

- The more gallons flowing through the BTR, the more rapid the

volume of water

accumulation.

– The harder the water the faster lime build up occurs. 1 to 3.5 grains per gallon is

hardness

"soft", 3.5 to 7 grains per gallon is "moderate", 7 to 10.5 grains per gallon is "hard" and 10.5 +

grains per gallon is "very hard". (An aspirin is about 5 grains. One grain is equal to 17.1 parts

per million.)

Deliming should be done when a slight rumbling or popping sound is detected when the main

burners are on.

What effect will lime build-up have on the BTR water heater?

One eighth inch of scale build-up may reduce efficiency as much as 22%; a 1/4 inch build-up,

as much as 38%.

Less efficient heat transfer means more bottom head expansion/contraction stress and

premature leakage.

Heavy build-up on the bottom head and bottom portion of the flue pipes leads to more heat

transfer at the top of the flues. This can lead to stacking or erratic thermostat operation.

Anode rods provide additional protection against corrosion. When should these be

replaced?

When large gouges or pits appear in the anodes, replace them. It is recommended that

these be inspected every 6 months.

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BTR MODELS 197 AND 198

Series 100-101

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BTR MODELS 197 AND 198 (continued)

Series 100-101

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PARTS LIST for BTR Models 197 and 198 Series 100 & 101

Item

Parts Description

BTR 197

BTR 198

098044(5)

192322

193873-0

193314-0

193314-1

99036

99037

69852

193325

192828

192957-4

76244-2

193927

76243-32

76243-49

43817-42 (4)

99465-7

193444

Bracket For Main Burner Orifice............... 098044(5)

Main Burner............................................. 192322

Main Burner w/Pilot Bracket..................... 193873-0

Pilot Burner Natural ................................. 193314-0

Pilot Burner Propane ............................... 193314-1

Gasket..................................................... 99036

Pressure Plate......................................... 99037

Screws, Self Tapping............................... 69852

Control, Ignition Module........................... 193325

Control, Dual w/ECO ............................... 192828

Drafthood................................................. 192957-4

Manifold................................................... 76244-2

Instruction Manual ................................... 193927

Main Burner Orifice Natural ..................... 76243-32

Main Burner Orifice Propane.................... 76243-49

Anode Rod............................................... 43817-38 (4)

T & P Relief Valve ................................... 99465-7

Transformer............................................. 193444

Inlet Tube ................................................ 192626

Gas Valve Natural.................................... 192827-2

Gas Valve Propane.................................. 192827-3

Off/On Switch .......................................... 193243

192626

192827-2

192827-3

193243

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BTR MODELS 120 through 500

Series 104-105

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BTR MODELS 120 through 500 (continued)

Series 104-111

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PARTS LIST FOR BTR Models 120 Through 500(A)

Series 104 Through 109 Series

(Series 106/107 have a service switch on Circuit Board 6522; Series 108/109 have new

main burner production method. Both parts will automatically be shipped

on 104 thru 109 series heaters.)

Item Parts Description

BTR-120 BTR-154 BTR-180 BTR-199 BTR-200

BTR-250

98044(5)

098047

193873-0

193314-4

193314-3

99036

Main Burner, Orifice Bracket

Main Burner

98044(3)

192322

193873-0

193314-0

193314-1

99036

98044(3)

98047

98044(5)

192322

193873-0

193314-0

193314-1

99036

98044(5)

192322

193873-0

193314-0

193314-1

99036

98044(5)

192322

193873-0

Main Burner w/Pilot Bracket

Pilot Burner, Natural

Pilot Burner, Propane

Gasket, Cleanout

193873-1

193314-0

193314-1

99036

193314-1

99036

Pressure Plate, Cleanout

Screw, Self tapping, Cleanout

Control, Ignition Module

Control, Dual w/eco

Drafthood

Drafthood 110, 111 Series

Manifold

Instruction Manual, (not illustrated)

Main Burner Orifice, Natural

Main Burner, Orifice, Propane

Anode Rod

T & P Relief Valve

Transformer

Inlet Tube

Gas Valve, Natural

Gas Valve, LP

Off/On Switch

99037

69852

193325

192828

193597-0

99037

69852

193325

192828

193597-1

99037

69852

193325

192828

192957-0

99037

69852

193325

192828

192957-0

99037

69852

193325

192828

192957-0

99037

69852

193325

192828

193287

76244-0

193927

76243-32

76243-49

76244-0

193927

76243-30

76243-46

76244-2

193927

76243-35

76243-51

76244-2

193927

76243-32

76243-49

76244-2

193927

76243-32

76243-48

76244-2

193927

76243-xx

43817-38 (2) 43817-38 (2) 43817-38 (4) 43817-38 (4) 180618-42 (3) 180618-42 (4)

99465-7

193444

99465-7

193444

192626

192827-2

192827-3

193243

99465-7

193444

193729

192827-2

192827-3

193243

99465-7

193444

193729

192827-2

192827-3

193243

99465-7

193444

192626

192827-2

192827-3

193243

192467

193444

192626

192827-2

192827-3

193243

193729

192827-2

192827-3

193243

Item Parts Description

BTR-251 BTR-275 BTR-305 BTR-365 BTR-400

BTR-500

98044(9)

192322

193873-0

193314-4

193314-3

99036

Main Burner, Orifice Bracket

Main Burner

98044(7)

98047

98044(5)

98047

98044(7)

192322

193873-0

193314-4

193314-3

99036

98044(9)

192322

193873-0

193314-4

193314-3

99036

98044(9)

192322

193873-0

193314-4

193314-3

99036

Main Burner w/Pilot Bracket

Pilot Burner, Natural

Pilot Burner, Propane

Gasket, Cleanout

193873-0

193314-4

193314-3

99036

193873-1

193314-4

193314-3

99036

Pressure Plate, Cleanout

Screw, Self tapping, Cleanout

Control, Ignition Module

Control, Dual w/eco

Drafthood

Drafthood 110, 111 Series

Manifold

Instruction Manual, (not illustrated)

Main Burner Orifice, Natural

Main Burner, Orifice, Propane

Anode Rod

T & P Relief Valve

Transformer

Inlet Tube

Gas Valve, Natural

Gas Valve, LP

Off/On Switch

99037

69852

193325

192828

193287

99037

69852

193325

192828

193287

99037

69852

193325

192828

193287

99037

69852

193325

192828

193287

99037

69852

193325

192828

193287

99037

69852

193325

192828

193287

76244-3

193927

76243-xx

76244-2

193927

76243-xx

76244-3

193927

76243-37

76243-48

76244-4

193927

76243-32

76243-49

76244-4

193927

76243-31

76243-48

76244-4

193927

76243-28

76243-44

43817-38 (4) 180618-42 (3) 43817-38 (4) 180618-42(4) 180618-42 (3) 180618-42 (4)

192467

193444

192827-2

192827-3

193243

192467

193444

192626

192827-2

192827-3

193243

192467

193444

192827-2

192827-3

193243

192467

193444

192626

192827-2

192827-3

193243

192467

193444

192626

192827-2

192827-3

193243

192467

193444

192626

193366-0

193366-1

193243

For complete parts list call 1-800-433-2545

∗

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COMPONENT PART INFORMATION

NAME

SPECIFICATIONS AOS PART NUMBERS

DUAL

120-180^ORANGE, + 4^O, 5^O

DIFFERENTIAL,

AOS # 192828

CONTROLLER THERMOSTAT

LIQUID FILLED, ANTI-

STACKING

HIGH LIMIT

(ECO)

OPENS - 205^OFIXED,

MANUAL

RESET BELOW 185^O

GAS VALVE NATURAL GAS BTR 120-400;24VAC, 60hz,

AOS # 192827-2

.6A,.7” to 3.5” W.C.,

STEP OPEN

BTR 500; 24VAC, 60hz,

Dual Gas Valve,

STEP OPEN

AOS # 193366-0

AOS # 192827-3

AOS # 193366-1

PROPANE

GAS

BTR 120-400;

2.5 – 10” W.C.

STEP OPEN

BTR 500; 24VAC, 60hz,

Dual Gas Valve,

STEP OPEN

INTERMITENT NATURAL GAS

24 VAC, 50-60 HZ, .1A;

.7 MICROAMP SIGNAL

CONTINUOUS RETRIAL

AOS 193325

IGNITION

DEVICE

AND

PROPANE

GAS

CONTROL

DAMPER

COMPLETE

ASSEMBLY

MOTOR

SEE PARTS LIST

AOS #6521

24 VAC, 60 HZ, 120 RPM,

5 WATT

P.C. BOARD

W/RELAY

Service Switch

AOS #6522

TRANSFORMER

120 V PRIMARY, 24 VAC

SECONDARY,

AOS #193444

40 VA, 50-60 HZ, CLASS 2

"B"

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BTR SERVICE CHECKLIST

(This service checklist may be photo copied to assist with BTR service call.)

This checklist is intended to aid the Service Agent in determining that the A.O. Smith

BTR Water Heater has been properly installed and is operating correctly. Because the

circumstances of each installation may vary greatly, it is not intended to be an all-

inclusive list of the problems that the Service Agent may encounter. Any item checked

"no" on this list should be thoroughly investigated and corrective action taken, if

required.

SERVICE AGENT

MODEL NUMBER

SERIAL NUMBER

INSTALLATION DATE

SERVICE DATE

LOCATION ADDRESS

GAS TYPE - CHECK ONE

NATURAL

PROPANE

PHONE(

)

___ -

____

Check Clearances (circle answer)

A. Are exterior clearances adequate?

B. Are interior clearances adequate?

yes

Comments:

II.

Check Makeup Air Requirements

A. Is the quantity of make-up air adequate per the National Fuel Gas Code?

yes

Comments:

B. Is the quality of make-up air adequate?

Comments:

III.

Gas Pressure (fill in blank)

Supply gas pressure

Manifold gas pressure (main burner)

inches of w.c.

Comments:

IV.

Venting (check)

Properly sized per the National Fuel Gas Code?

Does the installation have mechanically assisted venting?

yes

If so, is it operational?

yes

Comments:

WATER PIPING

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Is the system properly sized?

Is the system properly installed?

Are there any water leaks?

Does the installation have a recirculating system?

If so, is it operational?

yes

VI.

PROPER SEQUENCE OF OPERATION

During standby does damper close on standby?

During standby is pilot flame off?

On a call for heat does thermostat close?

On a call for heat does damper open completely?

Does sparking begin at pilot?

yes

Is pilot flame established?

If so, does sparking stop?

Does main burner ignite?

Does the thermostat satisfy?

Does damper close?

Comments:

VII.

SAFETY

A. Gas

Does pilot flame prove before main burner ignites?

Does damper blade fully open before ignition sequence occurs?

Is burner cover plate in place?

Is burner floor shield in place?

Does IID lockout occur after 30 sec. trial for ignition? (Propane models only)

yes

B. Water Temperature

Is the thermostat adjusted to the lowest acceptable temperature?

Does the installation have a mixing valve?

If so, is it operational?

yes

What is the outlet temperature of the mixing valve?

(To minimize the risk of scalding, the manufacturer recommends storing water at 120°F.)

NOTE:

Is a properly rated temperature and pressure relief valve installed?

yes

C. Electrical

Is the 120 VAC electrical power supply properly wired?

Are all the BTR control covers in place?

Is the 120 VAC electrical power supply properly fused?

yes

D. Flammables

Are flammable materials located in the area of the water heater?

Are flammable vapors located in the area of the water heater?

yes

Comments:

(This service checklist may be photo copied to assist with BTR service call.)

A.O. Smith Water Products

Service Handbook

1999 Training Department

BTR TANK TYPE HEATERS

SERVICE WORKBOOK

COMMENTS

Author: Terry Mulder

A.O. Smith Water Products

Service Handbook

1999 Training Department

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