Table Of Contents - A.O. Smith BTX 100 Service Handbook

TAblE Of CONTENTS .......................................................................... 1
INTRODUCTION .................................................................................... 2
Qualifications ..................................................................................... 2
Service Warning ................................................................................ 2
Service Reminder .............................................................................. 2
Tools Required ................................................................................... 2
INSTAllATION CONSIDERATIONS ..................................................... 3
Instruction Manual ............................................................................. 3
Closed Water Systems ...................................................................... 3
Thermal Expansion ............................................................................ 3
Air Requirements ............................................................................... 3
Contaminated Air ............................................................................... 3
Venting ............................................................................................... 4
General Venting Information ....................................................... 4
Maximum Equivalent Length Requirements ............................... 4
Intake Air Connection .................................................................. 5
Electrical Requirements ..................................................................... 6
Grounding and Polarity ............................................................... 6
Power Supply Test ...................................................................... 6
Installation Check List ........................................................................ 7
FEATuRES And CoMPonEnTS ......................................................... 8
Front & Back Views ........................................................................... 8
Top View ............................................................................................ 9
Combustion Blower & Burner Assembly ............................................ 9
OPERATION AND SERvICE ............................................................... 10
How It Works ................................................................................... 10
Combustion Blower ..........................................................................11
Burner Assembly ............................................................................. 12
Combustion Blower and Burner Removal ....................................... 14
Flame Sensor .................................................................................. 18
Flame Sensing operation ......................................................... 18
Flame Sensing Current Test ...................................................... 19
Igniter ............................................................................................... 20
Igniter Current Test .................................................................... 20
venturi ............................................................................................. 22
Gas valve ........................................................................................ 23
Gas Valve Voltage Tests............................................................ 23
Gas Valve Removal ................................................................... 24
Gas Pressure ................................................................................... 25
Gas Pressure Test ..................................................................... 26
Gas Flow Test ........................................................................... 27
Pressure Switches ........................................................................... 28
Construction & operation .......................................................... 28
Control System Monitoring ........................................................ 29
Pressure Switch Tests ..................................................................... 31
Continuity Test during Standby ................................................. 31
Continuity Test during operation .............................................. 32
Pressure Test during operation ................................................ 32
Temperature Probe .......................................................................... 35
Temperature Sensor Test .......................................................... 35
ECo Continuity Test .................................................................. 36

table of Contents

Control System Hardware ......................................................... 37
Wiring diagram .......................................................................... 44
ConTRoL SySTEM oPERATIon ................................................ 45
Overview .................................................................................... 45
Control System Menus .............................................................. 48
Sequence of operation ............................................................. 54
Sequence of operation Flow Chart .......................................... 55
TROUblESHOOTING ................................................................... 56
Control System unresponsive ................................................... 57
Fault Messages ......................................................................... 58
uIM (user Interface Module) ............................................... 37
CCB (Central Control Board) .............................................. 39
CCB Cover Removal And Replacement ............................. 40
CCB Circuit Board Layout ................................................... 41
CCB Connection Identification ........................................... 42
Control System Features .................................................... 45
Commercial And Residential Models .................................. 46
Control System navigation .................................................. 46
user Input Buttons .............................................................. 46
desktop Screen ................................................................... 46
Status Icons ........................................................................ 47
operating States ................................................................. 48
Temperatures ...................................................................... 49
Heater Status ...................................................................... 50
display Settings .................................................................. 51
Heater Information .............................................................. 51
Current fault ....................................................................... 52
Fault History ........................................................................ 52
Fault occurrence ................................................................. 52
Restore Factory defaults .................................................... 52
Service Contact Information ................................................ 53
Rough Starting/Rough operation ........................................ 56
not Enough Hot Water ........................................................ 56
Heater Status Menu ............................................................ 56
Things To Check Before Servicing ...................................... 56
Resetting The Control System ............................................ 56
uIM (LCd) Is Blank ............................................................. 57
uIM Is Inoperable ................................................................ 57
AC Reversed ....................................................................... 58
Temp Probe open ............................................................... 58
Temp Probe Short ............................................................... 58
Flame Sensor Short ............................................................ 59
Flame detect Error .............................................................. 59
Energy Cut out (ECo) ........................................................ 60
Blocked Air Intake ............................................................... 61
Blocked Exhaust ................................................................. 62
Blower Prover Failure .......................................................... 62
Blower Prover open ............................................................ 63
Low Igniter Current .............................................................. 64
Ignition Failure ..................................................................... 65
Communication Failure ....................................................... 66
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