A.O. Smith 110 User manual

110 Indoor / 110 Outdoor Service Manual
Ver. 1.01
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110 Direct Vent Indoor
and Outdoor Models
On-Demand Water Heater
Service Manual
110 Indoor
A.O. Smith Water Products Company
500 Tennessee Waltz Parkway
Ashland City,TN 37015
Toll Free: 1
-
877
-
73
7
-
2840
110 Outdoor

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Table of Contents
1.
Specifications………………………………………...…...………….……………………...…………………………
3
2.
Exterior view……………………...…….……………………………………………………………………………....
4
3.
Interior view…………………………….………………………………………………………………………………..
6
4.
Listof main components in the interior view…….……………………………………………………….
8
5.
Schematic diagram…………………………………………………………………………………………………….
10
6.
Wiring diagram………………………………………………………………………………………………………….
11
7.
Wiring diagram checkpoints for diagnosis………………………..………………….….…………………
12
8.
Resistance values of the temperature thermistors…………..…………………………………………
14
9.
Operational flow chart……………………………………………………………………………………………….
15
10.
Component specifications………………...……………………………………………………………………….
16
11.
FaultAnalysis &Specifications……………………………………………………………........................
35
12.
Controls and settings………………………………………………………………………………………………….
44
13.
Components diagrams………………………………………………………………..................................
58
14.
Parts list……………………………………………………………………………………………………………………..
61
15.
Revisions……………………………………………………...……………………………………………………………
65

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1. Specifications of the 110 Direct Vent Indoor* and 110 Outdoor
Model 110 Indoor 110 Outdoor
Dimensions H20.5"×W13.8"×D6.7"
Weight 33 lbs.
Combustion
INPUT
BTU/h Max 140,000
Min 19,500
Combustion System
Power vent
Installation Indoor & Direct-vent Outdoor
Fan motor PWM Multi blade fan
Manifold
Pressure**
Max
LP 2.6” WC
Natural 2.2” WC LP 3.0” WC Natural 2.7” WC
Min
LP 0.7” WC
Natural 0.6” WC LP 0.8” WC Natural 0.7” WC
Water control
Flow rate 0.75 to 6.6 GPM
Available set
temperatures 99°F to 167°F Default:122°F
Temperature
dipswitch settings
113°F, 122°F, 131°F, 140°F
Bypass valve N/A
Thermistors 2 thermistors (In, Out)
Operation
Remote controller
model 9007666005
PCB model 110
Indicators Red LED on PCB during operation
Powersupply
control Surge absorber and Power ON-OFF switch
Features
Freezeprotection
Ceramic heaters
Self-combustion
improvement Air-Fuel Ratio Detection System
Easy-Link system
N/A
Multiple-system
N/A
* The 310 DirectVent Indoor means the 110 Indoor in the text.
**The manifold pressure measurement is base on conditionswithout front cover.

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13-3/4" (350mm)
10" (254mm)
2-1/4" (56mm)
21-3/8" (544mm) 20-1/4" (520mm)
2-1/4" (56 mm) COLD
3-7/8" (98mm) GAS
4-7/8" (124mm) HOT
1" (26mm)
4" (102mm)
4-7/8" (123mm) 120 VAC
7-3/4" (196mm)
1-3/4" (45mm)1-3/4" (45mm)
1-7/8" (47mm)
COLD 3-1/8" (79mm)
HOT 5-1/4" (133mm)
120 VAC 1-3/8" (36mm)
GAS 4-7/8" (124mm)
2-1/4" (57mm)
13-1/8" (334mm)
6-1/4" (160mm)
1" (102mm)
COLD 2-1/4" (56mm)
HOT 4-7/8" (124mm)
HOT 5-1/4" (133mm) GAS 4-7/8" (124mm)
120 VAC 1-3/8" (36mm)
GAS 3-7/8" (98mm)
120VAC 4-7/8" (123mm)
COLD 3-1/8" (79mm)
2. Exterior view
110 Indoor
Side view
Front view
Top view
Bottom view

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13-3/4" (350mm)
10" (254mm)
21-3/8" (544mm) 20-1/4" (520mm)
2-1/4" (56 mm) COLD
3-7/8" (98mm) GAS
4-7/8" (124mm) HOT
1" (26mm)
4-7/8" (123mm) 120 VAC
7-3/4" (196mm)
1-3/4" (45mm)1-3/4" (45mm)
1-7/8" (47mm)
COLD 3-1/8" (79mm)
HOT 5-1/4" (133mm)
120 VAC 1-3/8" (36mm)
GAS 4-7/8" (124mm)
13-1/8" (334mm)
COLD 2-1/4" (56mm)
HOT 4-7/8" (124mm)
HOT 5-1/4" (133mm) GAS 4-7/8" (124mm)
120 VAC 1-3/8" (36mm)
GAS 3-7/8" (98mm)
120V 4-7/8" (123mm)
7-7/8" (203mm)
1-5/8" (43mm)
COLD 3-1/8" (79mm)
110 Outdoor
Side view
Front view
Top view
Bottom view

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3. Interior view
110 Indoor
1
10
11
24
2
4
28
27
29
17
13
148256
7
9
3
5
20
26
22
23
18
12
16
19
15
30

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110 Outdoor
1
10
11
24
2
4
28
27
29
17
13
14825
6
7
9
3
5
20
26
22
23
18
12
16
19
15
30

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4. List of main components in the interior view
No.
Description Item# in components
diagram
AOS
Part# Common parts for other models
1 Case assembly 001
319143-159
(110 Indoor)
319143-172
(110 Outdoor)
2Manifold assembly with
gas valve assembly 102 319143-169 (LP model)
319143-165 (NA model)
3 Computerboard 701 319143-164
4 Igniter 711 319143-052 520, 310,510, 910, 710
5 Transformer 702 319143-182 310, 510
6 Water inlet 404 319143-193 310,510
7 Wateroutlet 409 319143-194 310,510
8 Inlet thermistor 407 319143-214 310
9 Outletthermistor 408 319143-218 310
10
Overheat cut-off fuse 413 319143-149 310,510, 910
11
Burnerassembly (Burners)
101 319143-161
12
Hi-limitswitch 412 319143-228 310
13
Fan motor 103 319143-347
14
Freeze protection
thermostat
713 319143-185 310,510, 710
710 319143-210 310,510
15
Flow sensor 402 319143-167 310
16
Heatexchanger assembly
401
319143-162
(110 Indoor)
319143-166
(110 Outdoor)
17
Gas inlet 118 319143-050 520, 310, 510
18
Heater 414 319143-200 310,510
19
Flow adjustment valve 402 319143-167 310

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No.
Description Item# in components
diagram
AOS
Part# Common parts Forother models
20
Surge box 703 319143-168 310,510
21
Outletdrain plug 410 319143-199 310,510, 910
22
Air-fuel ratio rod (AFR rod)
108 319143-339
23
Flame rod 108 319143-339
24
Igniter rod 109 319143-373
25
Inlet drain plug
(water filter) 405 319143-197 310,510
26
120 VAC
PowerON-OFF switch 706 319143-141 520, 310, 510
27
Gas valve assembly 102 319143-169 (LP model)
319143-165 (NA model)
28
Manifold port N/A N/A
29
Gas inletport N/A N/A
30
Exhaustchamber Included in
401
319143-162
(110 Indoor)
319143-166
(110 Outdoor)

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5. Schematic diagram
The diagram below refers to both the 110 Indoorand 110 Outdoor.
1. When a hot water tap is opened,cold water enters the 110 Indoor or 110 Outdoor.
2. The water flow sensor detects this water flowand sends this information tocomputer.
3. The computer initiates fan motorand sends signal to igniterto create ignition spark.
4. The main, proportional, and solenoid gas valves open to allow gas input.
5. The gas ignitesand flames appear inside the burner chamber.
6. Water circulates through the heat exchanger and is heated up to the settemperature.
7. Using thermistors to measure temperatures, the computer modulates the gas and water valves to
ensureproperoutputwatertemperatures.
8. When the tap is closed, the 110 Indoor or 110 Outdoor shutsdown.
H
O
T
C
O
L
D
G
A
S
Hi-limit SW
Inlet drain
plug filter
Outlet
Thermistor
Drain plug
Main gas valve
Gas solenoid valve 2
Fan motor
Flame rod
Igniter rod
Igniter
O.H.C.F
Heater
Flow adjustment valve
with Flow sensor
Gas proportional valve
Gas solenoid valve 1
Air-fuel ratio rod
Gas solenoid valve 3
Inlet
Thermistor Transformer
PCB

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6. Wiring diagram
The diagram below refers to both the 110 Indoorand 110 Outdoor.
W: WHITE R: RED
BK: BLACK
P: PURPLE
L
B
:
L
I
G
H
T
B
L
U
E
BL: BLUE
G: GREEN
Y: YELLOW
O: ORANGE BR: BROWN
9007666005
Gas
Propor-
tional
Valve
3
9
53
73
G
W
BK
Trans-
former
IG
Igniter rod
Heater
Thermostat
Heater
Ground
BK
BK
MV
SV3
SV2
SV1
LB
G
O
R
O.H.C.F
Hi-
limit
BL
BLBL
BL
BL
BL
BL
W
Y
BL
O
R
FM
W
R
Flow
Sensor
Flame rod Ground
Air-fuel ratio rod
Y
G
O
Inlet
thermistor
Outlet
thermistor Remote
controller
654321
BK
Flow
Adjust
Valve
R
BK
OFF
PP
PP
BR
BR
120 VAC
G
Ground
BK
W
WBK
BR
BR
SW
Surge
box
W
BK
BK
Increase button
Decrease button
Dipswitches
Red LED
MAX button
MIN button
78
PCB
G
F
H2
E2
E1
H1
C2
C
B1
B
A
C1
A2
A1
J
I A3

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7. Wiring diagram check points for diagnosis
The table below applies to both the 110 Indoor and 110 Outdoor.
Check-
point
Part and Description Color of wires Normal range
A, A1
100V Power supply White – Black (A)
Brown – Brown (A1) 90 to110 VAC
A2,A3
120V Power supply Black - White 108 to 132 VAC
B Igniter Purple - Purple 90 to 110 VAC
B1 Heater Black - Black 90 to110 VAC
C Gas valves
Light blue - blue at COM (MV)
78 to 100 VDC (duringoperation)
/0.9 to 1.3 kΩ
Green - blue at COM (SV1) 78 to 100 VDC
(duringoperation)
/1.3 to 1.9 kΩ
Orange - blue at COM (SV2)
78 to 100 VDC (duringoperation)
/1.3 to 1.9 kΩ
Red - blue atCOM (SV3) 78 to 100 VDC
(duringoperation)
/0.9 to 1.7 kΩ
C1 Hi-limit switch Blue - Blue Less than 1 VDC and
less than 1.0 Ω
C2 Overheatcutoff fuse Blue - Blue Less than 1VDC and
less than 1.0 Ω
E1 Outlet thermistor Black -Black See table on p. 14
E2 Inletthermistor Black -Black
F Remotecontroller * 11 to25VDC
G Fan motor Red - Blue 110 to 160 VDC Yellow - Blue 13 to17 VDC
Orange - Blue 2 to 6.5 VDC

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Check-
point
Partand Description Colorof wires Normalrange
H1 Gas proportional valve White - red 1 to 15 VDC (during operation)
and
20 to40 Ω
H2 Flow sensor
Red - Black 4 to 5.5 VDC
White - Black 1 to 4 VDC (pulse) 1,080 pulse /min
(more than 18 Hz)
I
Air-fuelratio rod Yellow - AFR rod (Between AFR rod and
the computer board)
More than 0.5 μA
(during operation)
Flame rod Orange -Flame rod (Between flame rod and
the computer board)
More than 1 μA
(during operation)
J Flow adjustmentvalve Red - Black 7 to16 VDC and 0.09 to0.2 kΩ

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8. Resistance values of the temperature thermistors
The 110 Indoor and 110 Outdoor use the same thermistors.
ºF 32 41 50 59 68 77 86 95 104 113
ºC 0 5 10 15 20 25 30 35 40 45
Resistance kΩ23.76 19.08 15.43 12.56 10.28 8.47 7.02 5.85 4.90 4.12
Temperature ºF 122 131 140 149 158 167 176 185 194 203 212
ºC 50 55 60 65 70 75 80 85 90 95 100
Resistance kΩ3.49 2.96 2.53 2.16 1.86 1.60 1.39 1.21 1.05 0.92 0.81
Temperature(ºF) vs. Resistance(kΩ)
Temperature(℃)vs. Resistance(kΩ)
Temperature
0.00
5.00
10.00
15.00
20.00
25.00
20 40 60 80 100 120 140 160 180 200 220
Temperature (ºF)
Resisitance (kΩ)
0.00
5.00
10.00
15.00
20.00
25.00
0 10 20 30 40 50 60 70 80 90 100
Temperature (ºC)
Resisitance (kΩ)
Resistance values at different temperatures

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9. Operational flow chart
The diagram below refers to both 110 Indoor and 110 Outdoor.
Power supply ON
Operation SW ON
FAV open
Pre-check
NORMAL?
Faucet opens
Water Flow
Above 0.75GPM?
FM speed
(Below
1,000rpm?)
Fan moter start
operation
False flame
Below
DC0.15 A?
Igniter ON
Hi-limit
Normal?
OHCF
Normal?
MV ON
SV2 ON
GPV ON
Flame rod
detects Above
DC1.0 A?
Burning lamp ON
Igniter OFF
Proportional control
BTU
change over
point?
SV1 SV3 ON
Below water
heat capability?
FAV OPEN
Safety devices
sensed
abnormal condition
FAV close
SV1 SV3 OFF
False Dipswitch
settings
InTH failure
SV circuit failure
MV circuit failure
03 blink
32 blink
51 blink
55 blink
61 blink
Fan motor stop
operation
72 blinkFalse flame
Igniter OFF
Reignition
Success?
OuTH OPEN
or SHORT Fan motor fault
MV OFF
SV2 OFF
GPV OFF
SV1 SV3 OFF
Fan motor stop operation
Faucet closes
Flow sensor OFF
Remove cause
Opeartion lamp OFF
Operation stop
YES
NO
YES
NO
NO
YES
YES
NO
(20sec later)
YES
NO
NO
YES
YES
NO
YES
NO
(5sec later)
YES
YES
NO
YES
NO
(20sec later)
YES
NO
NO
NO
YES
FM speed
(Above
1,000rpm?)
Below
Max flow rate
restriction?
11 blink
12 blink
31 blink
OuTH failure 31 blink
PCB failure 70 blink
Flame
blows out
OHCF melted
(above 430 F)
AFR rod failure Abnormal
burning
12 blink12 blink99 blink39 blink
32 blink
InTH OPEN
or SHORT
61 blink
FAV ; Flow Adjustment Valve
F M ; Fan Motor
OHCF; Over Heat Cut-off Fuse
M V ; Main gas Valve
SV1 ; Solenoid Valve 1
(See the section 6)
SV2 ; Solenoid Valve 2
(See the section 6)
SV3 ; Solenoid Valve 3
(See the section 6)
GPV ; Gas Proportional Valve
InTH; Inlet thermistor
OuTH; Outlet thermistor
PCB ; Print Circuit board
(Computer board)
AFR ; Air Fuel Ratio rod

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10. Component specifications
10-1.
Burners……………………..…………………………………………………….......................……….
17
10-2.
Gas manifold………….…………………………………………………………..............................
18
10-3.
Fan motor………………………………………………………………………...……………………………
19
10-4.
Gas valve assembly………………..……………………….……………………………………………..
20
10-5.
Flame rod………………………………………………………….…………………………………………..
21
10-6.
AFR rod………………………………………………………………………………………………………….
22
10-7.
Heatexchanger………………………………………………………………………………………………
23
10-8.
Flow adjustment valve…………….……………………………………….....………………………..
24
10-9.
Flow sensor……………………………………..…………………………………………………………….
25
10-10.
Thermistors……….………………………..……………………………………..………………………….
26
10-11.
Hi-limit switch…………………..…………………………………………………...........................
27
10-12.
Overheat cutoff fuse…..………………………………………………………….........................
28
10-13.
Freeze protection heaters…………….………………………………………………………………..
29
10-14.
Computerboard……………….……………………………………………………………………………
30
10-15.
Transformer. ………...……………………………………………………………………………………….
31
10-16.
Igniter………………………………………………………………………………...............................
32
10-17.
Freeze protection thermostat…………………………………………………….....................
33
10-18.
Surge box…………………………………………………………………….……..............................
34

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CONFIDENTIAL
10-1. Burners
Unit Part ##101 AOS Part #319143-161
Checkpoint N/A
Function
There are 2 types of burners in the water heater: the gas-rich burner
stabilizes the flames within the combustion chamber and the air-rich
burner produces more heat in the combustion chamber. The burners
facilitate the air/gas mixture necessary to produce the proper heat during
the combustion reaction.
Failure events
1. Unable to initialize/sustain combustion
2.Dust or soot deposit on the burner surface.
3. Cracks on the burners.
4. Gas leakage from
the
burners
Effects on the water heater
if burners fails
1. Unexpected combustion.
2. Unstable flame conditionsand/or flame loss.
3. Ignition failure.
4.Back-firing.
Error codes when the
burners fails 10 11 12 99
Diagnostic Visual inspection: excessive dust deposit on the burner surface and/or
unstable flame conditions during operation.
Color/Numberof wires N/A
The burner for the 110 Indoor and 110 Outdoor has the “46B” mark as shown below.
Burnerdamper (#112 /319143-170)
The burner damper is not
included in 319143-161.
7-7/8" (201mm)
1-3/4" (44mm)
FE
"FE" mark
5-1/4" (132mm) 5-7/8" (152mm)
46B
"46B" mark
8-7/8" (228mm)

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10-2. Gas manifold
Unit Part #Included
in #102 AOS Part #319143-169 (LP) 319143-165 (NA) Checkpoint N/A
Function
1. The manifold distributes gas from the gas valves to the burners. The
manifold has two types of the nozzles: one type for gas-rich burners (16
nozzles) and the other for air-rich burners (15nozzles)
2. There are 3 zones within the manifold, to ensure efficient combustion
operation.
Failure events
1. Dust depositon the manifold.
2. Gas leakage from a failed manifold.
3. Ignition failure.
4. Imperfect combustion.
Effects on the water
heater if the manifold
fails
1. The burners cannot receive proper gas flow from the manifold, which can
cause poor combustion in the combustion chamber. In this case, the AFR
rod will detect an improper flame condition and computer will take safety
measures.
2. Gas leakage from the manifold.
Error codes when the
manifold fails 10 11 12 99
Diagnostic 1. Visual inspection: Excessive dust deposit around the nozzles or cracks on
the manifold.
2. Check voltages and resistance: proper range of values shown below.
Color/Numberof wires Blue-Red 78 to 100 VDC /0.9 to 1.7 kΩ
Nozzles for gas-rich burners
Nozzles for air-rich burners
319143-169 (for LP model)
and 319143-165 (for NA
model) is an assembly of
the gas manifold with the
gas valve assembly. For
safety reasons, these
assemblies should be
installed in the unit as a
whole set.
The gas manifold for the LP
has the “27G” mark, and
the gas manifold for the NA
has the “46B” mark on the
manifold plate.
9-1/8" (232mm)
6-7/8" (175mm)
27G
46B
"27G" mark (LP)
"46B" mark (NA)

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10-3. Fan motor
Unit Part ##103 AOS Part #319143-347 Checkpoint G
Function To provide combustion air into theburner chamberand to exhaustflue gas.
Failure events
1. Fan speed failure, causing abnormal sounds with or without combustion
during operation.
2. Unexpected activation caused by the connectors of the fan motor getting
wet.
3. Disconnects out from the bottom of the combustion chamber
Effects on the water
heater if fan motor fails
1. The water heater doesnot function properly
2. Failure to ignite or abnormal ignition
3. Unstable combustion conditions
Error codes when the fan
motor fails 10 11 12 61 99
Diagnostic 1. Visual inspection: connection/breakage of wires or dust (causing electrical
shortage)
2. Voltage check: proper range of voltages shown below.
Color/Numberof wires
Red-Blue 110 to 160 VDC (Input)
Yellow-Blue 13 to17 VDC (Input)
Orange-Blue 2.0 to 6.5 VDC (Input)
White-Blue Verify the fan motor speed using the Diagnostics Mode of
the 9007666005 temperature remote controller. See
Section 12-1 fordetails.
Fan damper (#115 / 319143-160)
PWN multi blade fan motor
The fan damper
is not included in
319143-347.
5-7/8" (151mm)
3-1/4" (86mm)
46
5-3/8" (137mm)
"46" mark
Opening 1-3/4" ( 46mm)
1-1/4"
( 33mm)

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10-4. Gas valve assembly
Unit Part ##102 AOS Part #
319143-169 (LP)
319143-165 (NA) Checkpoint C,H1
Function Opens and closes the gas pathways of the water heater (main and solenoid
gas valves)
Modulates the gas flow from the gas inlet (proportional gas valve)
Failure events 1. Gas leak from the valves.
2. Unable to open/close (main and solenoid gas valves)
3. Unable to modulate the gas flow (proportional gas valve)
Effects on the water
heater if valves fails
1. Gas leak from the unit.
2. Excess carbon monoxide emissions. / No flames.
3. Lack of water temperaturecontrol.
Error codes when the
valves fails 11 12 51 70
Diagnostic
1. Visual inspection: connection/breakage of wires.
2. Listen for "clunk" sounds from the gas valves opening right after fan motor
initiates.
3. Check voltages and resistance of coils; proper range of values shown
below.
Color/Numberof wires
Blue - Light blue (MV) 78 to 100 VDC (duringoperation) /0.9 to1.3 kΩ
Blue - Green (SV1) 78 to 100 VDC (duringoperation) /1.3 to 1.9 kΩ
Blue - Orange (SV2) 78 to 100 VDC(during operation) /1.3 to 1.9 kΩ
Blue - Red (SV3) 78 to 100 VDC (during operation) / 0.9 to1.7 kΩ
White –Red
(Proportional valve) 1.0 to 15 VDC (during operation) /20 to 40 Ω
Proportional Valve
Proportional valve
Main gas valve
4-1/4" (108mm) 7/8" (22.2mm)
4-5/8" (119mm)
Solenoid valve
Gas
valve
3-5/8" (91.5mm)
1-3/8" (34mm)
2-5/8" (67mm)
319143-169 (for LP model) and 319143-165 (for NA
model) is an assembly of the gas manifold with gas
valve assembly. For safety reasons, these assemblies
should be installed in the unit as a whole set. The
diagram below shows the gas valve assembly.