A.O. Smith T-H3J-DV User manual

A.O. Smith Water Products
Company
500 Tennessee Waltz Parkway
Ashland City, TN 37015
Toll Free: 1-877-737-2840
240 (T-H3J), 340 (T-H3S)
and 540 (T-H3) Models
On-Demand Water Heater
Service Manual

2Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
Table of Contents
1. Specifications....................................................................................................................
2. Exterior view.....................................................................................................................
3. Interior view.......................................................................................................................
4. List of main components in the interior view...................................................................
5. Schemac diagram............................................................................................................
6. Wiring diagram.................................................................................................................
7. Wiring diagram checkpoints for diagnosis........................................................................
8. (A) Resistance values of the temperature thermistors.....................................................
8. (B) Resistance values of the temperature exhaust thermistors........................................
9. Operaonal ow chart......................................................................................................
10. Component specicaons................................................................................................
11. Fault Analysis & Specicaons.........................................................................................
12. Controls and sengs........................................................................................................
13. Components diagrams......................................................................................................
14. Parts list............................................................................................................................
15. Revisions...........................................................................................................................
3
4
6
10
13
14
16
18
19
20
21
47
58
89
93
104

3Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
1. Specifications
Model 240
Indoor
(T-H3J-DV)
240
Outdoor
(T-H3J-OS)
340
Indoor
(T-H3S-DV)
340
Outdoor
(T-H3S-OS)
540
Indoor
(T-H3-DV)
540
Outdoor
(T-H3-OS)
Dimensions inch H 22.4 x W 17.7 x D 10.7
570 (H) x 450 (W) x 272 (D)
mm
Weight lbs. (kg) 58 (26.3) 58 (26.2) 58 (26.3) 58 (26.2) 58 (26.8) 58 (26.9)
Combustion
INPUT
BTU/h
Max 160,000 180,000 199,000
Min Propane 13,000
Natural gas 15,000
Combustion
system
Installation
Power vent
Installation Direct-vent
Indoor Outdoor Direct-vent Indoor Outdoor Direct-vent Indoor Outdoor
Fan motor PWM turbo fan
Manifold
Pressure*
("W.C.)
Max Propane 2.2
Natural 1.9
Propane 2.2
Natural 2.0
Propane 2.6
Natural 2.4
Propane 2.7
Natural 2.4
Propane 3.2
Natural 2.8
Propane 3.2
Natural 2.9
Min Propane 0.6
Natural 0.7
Propane 0.7
Natural 0.7
Propane 0.6
Natural 0.7
Propane 0.7
Natural 0.7
Propane 0.6
Natural 0.7
Propane 0.7
Natural 0.7
Water control
Flow rate GPM 0.5 to 6.6 0.5 to 8.0 0.5 to 10.0
Available
set
temperatures
°F
(°C)
100 to 140 (38 to 60)
default: 120 (49)
100 to 185 (38 to 85)
default: 120 (49)
Temperature
DIPswitch
settings
°F
(°C) 120 (49), 140 (60)
Bypass valve N/A Yes
Thermistors 2 thermistors (In, Out) 3 thermistors
(In, Out, Heat exchanger)
Operation
Temperature
control
Temperature controller : Direct Vent Indoor models
Temperature remote controller (TM-RE40) : Outdoor models
PCB model 240
Part # 319143-543 (EK186)
340
Part # 319143-544 (EK175)
540
Part # 319143-545 (EK176)
Indicators Stand-by LED
Power supply
control Surge absorber & Power ON-OFF switch
Features
Freeze
protection
Ceramic heaters (All models) and
Auto-firing system (Only 540 Direct Vent Indoor models (T-H3-DV) models)
Self-
combustion
improvement
Air-Fuel Ratio Detection System
Easy-Link
system N/A Yes (Up to 4 units)
Multiple-
system N/A Yes (Up to 20 units)
*The manifold pressure measurement is based on conditions without front cover.

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
2. Exterior view
Direct Vnet Indoor models
Side view
Front view
7-7/8" (199 mm)
GAS 5-1/8" (131 mm)
COLD 6-3/4" (172 mm)
HOT 5-1/2" (140 mm)
7-1/2" (189 mm)
GAS 5-7/8" (147 mm)
Condensate drain port
COLD 5/8" (17 mm)
HOT 4-3/4" (120 mm)
17-5/8" (448 mm)
6-1/4" (159 mm)
5-3/4" (147 mm)
120 VAC 3" (77 mm)
120 VAC 6-7/8" (174 mm)
∅
Drain port
Female
10-3/4" (272mm)
22-1/22" (570 mm)
Condensate drain port
4" (102 mm)
2-5/8" (68 mm)
Exhaust
Intake
Female
∅
7-7/8" (199 mm)
7-1/2" (189 mm)
7" (180 mm) 4" (101 mm)
17-3/4" (450 mm)
HOT 4-3/4" (120 mm)
6-3/4" (170 mm)
COLD 5/8" (17 mm)
GAS 5-3/4" (147 mm)
Condensate drain port
23-5/8" (600 mm)
2-5/8" (65 mm)
5-3/4" (147 mm)
11-1/4" (285 mm)
1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
COLD 6-3/4" (172 mm)
Condensate drain port
6-1/4" (159mm)
4" (102 mm)
24-7/8" (631 mm)
120 VAC 3" (77 mm)
Drain port 6" (152 mm)
120 VAC 6-7/8" (174 mm)
Bottom view Top view

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
Outdoor models
Side view
Front view
17-5/8" (448 mm)
6-1/4" (159 mm) COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
HOT 5-1/2" (140 mm)
HOT 4-3/4" (120 mm) 7-1/2" (189 mm)
Condensate drain port
GAS 5-1/8" (131 mm)
COLD 6-3/4" (172 mm)
7-7/8" (199 mm)
Drain port
7-1/2" (189 mm)
10-3/4" (272 mm)
22-1/2" (570 mm)
120 VAC
Condensate drain port
7-7/8" (199 mm)
Condensate drain port
11" (281 mm)
1/2" (13 mm)
120 VAC 3" (77 mm)
GAS (131 mm)
HOT (140 mm)
COLD 6-3/4" (172 mm)
Condensate drain port
COLD 5/8" (17 mm)
GAS 5-3/4" (147 mm)
HOT 4-3/4" (120 mm)
6-3/4" (170 mm)
1-1/2" (37 mm)
11-1/4" (285 mm)
120 VAC 6-1/4" (159 mm)
17-3/4" (450 mm)
7" (180 mm)
23-5/8" (600 mm)
24-7/8" (631 mm)
3-5/8" (92 mm)
4-1/2" (114 mm)
Drain port 6" (152 mm)
Bottom view Top view

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
3. Interior view
240 Indoor (T-H3J-DV)
340 Indoor (T-H3S-DV)
1
2
3
4
5
6
79
10
11
12
13
14
15
16
18
19
20
21
22
23
24
26
28
27
29
30
31
31
33
33
17
33
37
38
34
39
32
32
REMOTE
CONTROLLER
OFF ON
AC120V
8
25

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
240 Outdoor (T-H3J-OS)
340 Outdoor (T-H3S-OS)
1
2
3
4
5
6
78
9
10
11
12
13
14
15
16
18
19
20
21
22
23
24
25
26
28
27
29
35
30
31
31
33
33 17
34
39
32
32
REMOTE
CONTROLLER
OFF ON
AC120V

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
540 Indoor (T-H3-DV)
1
2
3
4
5
6
78
9
10
11
12
13
14
15
16
18
19
20
21
22
23 24
25
26
28
27
29
35
30
31
31
33
33 17
33
36
37
38
34
39
32
32
AC120V
REMOTE
CONTROLLER
OFF ON

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
540 Outdoor (T-H3-OS)
1
2
3
4
5
6
78 9
10
11
12
13
14
15
16
18
19
20
21
22
23
24
25
26
28
27
29
35
30
31
31
33
33
17
36
34
39
32
32
REMOTE
CONTROLLER
AC120V
OFF ON

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
4. List of main components in the interior view
No. Description
Items# in
components
diagram
Part #
240, 340 and
540 models
T-H3J, T-H3S and
T-H3 models
1. Case assembly
Indoor
models 001
N/A EK159
Outdoor
models N/A EK164
2.
Manifold
assembly with
gas valve
assembly
LP model
102
319143-515 EK181
NA model 319143-516 EK182
3. Computer board 701
319143-543
(240 models)
EK186
(T-H3J models)
319143-544
(340 models)
EK175
(T-H3S models)
319143-545
(540 models)
EK176
(T-H3 models)
4. Igniter 711 319143-479 EK153
5. Gas valve
assembly
LP model Included in
#102
319143-515 EK181
NA model 319143-516 EK182
6. Water inlet 404 319143-193 EKK1U
7. Water outlet 409 319143-530 EK208
8. Inlet thermistor 407
319143-214
(240/340 models)
EKK4J
(T-H3J/T-H3S models)
319143-465
(540 models)
EK137
(T-H3 models)
9. Outlet thermistor 408
319143-529
(240/340 models)
EK207
(T-H3J/T-H3S models)
319143-190
(540 models)
EKK1A
(T-H3 models)
10. Overheat cut-off fuse 413 319143-149 EK333
11. Burner assembly 101 319143-514 EK192
12. Hi-limit switch 412
319143-228
(240/340 models)
EM212
(T-H3J/T-H3S models)
319143-095
(540 models)
EKN34
(T-H3 models)

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
No. Description
Items# in
components
diagram
Part #
240, 340 and
540 models
T-H3J, T-H3S and
T-H3 models
13. Fan motor
Indoor
models 103
319143-443 EK109
Outdoor
models 319143-043 EKK25
14.
Freeze
protection
thermostat
Indoor
models 713
319143-496 EK184
Outdoor
models 319143-497 EK185
15. Flow sensor 402 319143-463 EK129
16.
Primary heat
exchanger
assembly
Indoor
models
401
319143-525
(240/340 models)
EK198
(T-H3J/T-H3S models)
319143-527
(540 models)
EK200
(T-H3 models)
Outdoor
models
319143-526
(240/340 models)
EK199
(T-H3J/T-H3S models)
319143-528
(540 models)
EK206
(T-H3 models)
17.
Secondary heat
exchanger
assembly
Indoor
models
Included in
#401
319143-525
(240/340 models)
EK198
(T-H3J/T-H3S models)
319143-527
(540 models)
EK200
(T-H3 models)
Outdoor
models
319143-526
(240/340 models)
EK199
(T-H3J/T-H3S models)
319143-528
(540 models)
EK206
(T-H3 models)
18. Gas inlet 118 319143-455 EK117
19. Flow adjustment valve 402 319143-463 EK129
20. Surge box 703 320273-128 EK280
21. Outlet drain plug 410 319143-199 EKK2E
22. AFR rod 108 319143-517 EK193
23. Flame rod 108 319143-517 EK193
24. Igniter rod 109 319143-037 EKK0F
25. Inlet drain plug
(water filter) 405 319143-197 EKK2B
26. 120 VAC
Power ON-OFF switch 706 319143-141 EKK4V

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
No. Description
Items# in
components
diagram
Part #
240, 340 and
540 models
T-H3J, T-H3S and
T-H3 models
27. Manifold port N/A N/A N/A
28. Gas inlet port N/A N/A N/A
29. Exhaust
chamber
Indoor
models
Included in
#401
319143-525
(240/340 models)
EK198
(T-H3J/T-H3S models)
319143-527
(540 models)
EK200
(T-H3 models)
Outdoor
models
319143-526
(240/340 models)
EK199
(T-H3J/T-H3S models)
319143-528
(540 models)
EK206
(T-H3 models)
30. Secondary heat exchanger
drain plug 411 319143-096 EKK2T
31. Pipe heater 414 319143-531 EK209
32. Inlet / Outlet heater 417 319143-468 EK105
33. Block heaters
Indoor
models 415
319143-532 EK210
Outdoor
models 319143-533 EK211
34. Flat heater 464 319143-535 EK217
35. Heat exchanger thermistor 411 319143-096 EKK2T
36. Bypass valve 403 319143-464 EKD58
37. Hi-Limit switch for exhaust 472 319143-104 EKH6G
38. Exhaust thermistor 471 319143-111 EX13L
39. Condensate drain port 009 319143-018 EKH23

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
5. Schematic diagram
The diagram below refers to both the Direct Vent Indoor models and Outdoor models.
1. When a hot water tap is opened, cold water enters the water heater.
2. The water flow sensor detects this water flow and sends this information to computer.
3. The computer initiates fan motor and sends signal to igniter to create ignition spark.
4. The main, proportional, and solenoid gas valves open to allow gas input.
5. The gas ignites and flames appear inside the burner chamber.
6. Water circulates through the heat exchanger and is heated up to the set temperature.
7. Using thermistors to measure temperatures, the computer modulates the gas and water valves to
ensure proper output water temperatures.
8. When the tap is closed, the water heater shuts down.
The Direct Vent Indoor models detects the exhaust temperature by using
exhaust thermistor and hi-limit switch for exhaust during procedures of 3 to 8.
NOTICE
HOT COLD
GAS
Hi-limit switch
Inlet drain
plug filter
Outlet thermistor
Drain plug
Main gas valve
Gas solenoid valve 2
Fan motor for combuson
Igniter
O.H.C.F
Flow adjustment valve
with Flow sensor
Gas proporonal valve
Gas solenoid valve 1
Gas solenoid valve 3
Heat exchanger thermistor
Inlet thermistor
Exhaust thermistor
Intake port
120
Exhaust
Secondary heat exchanger
Primary heat exchanger
Hi-limit switch for exhaust
540 (T-H3) models only
Drain pan
Condensate drain
PCB
ON-OFF-switch for power supply
Surge box
Bypass valve
Direct Vent Indoor models only
Flame rod
Igniter rod
Air-fuel rao rod
Heater
VAC

14 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
6. Wiring diagram
W: WHITE
R: RED
BK: BLACK
P: PURPLE
LB: LIGHT BLUE
BL: BLUE
G: GREEN
Y: YELLOW
O: ORANGE BR: BROWN
240 (T-H3J) models / 340 (T-H3S) models
9
8
7
65
4
3
21 10
OFF
Temperature remote controller
R
BK
RW
BK
Ground
G
O
W
YBL
O
R
PCB
W
120 VAC
G
Ground
SW
Ground
WBK
G
Igniter rod
P
73
53
9
3
O
R
G
LB
BL
O.H.C.F
BL
Hi-
limit
Switch BL
Gas
Propor-
onal
Valve
W
R
BL
BL
BL
BL
P
BK
BK
W
BK
BK
Outlet thermistor
Inlet thermistor
Surge
box
Hi-limit switch
for exhaust
Exhaust
thermistor
W
W
W
WBK
W
BL R
BK Temperature controller
Heater
Heater
Heater
240/340 Outdoor
Heater
BK
Bank of DIPswitches
Y
Y
Y
Y
Y
Y
WW
W
Y
Flame rod
AFR rod
BK
W
Thermostat
Heater
Heater
Heater
240/340 Direct Vent Indoor
Decrease buon
Increase buon
MIN buon
MAX buon
Green LED
SV3
SV2
SV1
MV
IG
Flow
Adjust-
ment
Valve
Flow
Sensor
FM
240/340 Direct Vent Indoor Only
240/340 Direct Vent
Indoor Only
B1
A1
A2
F
J
I
H2
G
A
E2
E1
H1
B
C
C2
C1
K2
K1
L
B1

15 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
540 (T-H3) models
W: WHITE
R: RED
BK: BLACK
P: PURPLE
LB: LIGHT BLUE
BL: BLUE
G: GREEN
Y: YELLOW
O: ORANGE BR: BROWN
87
65
4
3
2
1
ON
654
3
2
1
ON
R
W
GY
PCB
W
120 VAC
G
Ground
SW
Ground
BK
W
GBK
W
Surge
box
73
53
9
3
BL
BL
R
BK
R
WBK
BK
BK
BK
BK
BK
WBK
WBK
Hi-limit switch
for exhaust
Exhaust thermistor
W
WW
W
Heater
Y
Y
Thermostat
BK
O
Ground
Flame rod
AFR rod
BK
W
WBL
RBK Temperature controller
BK
BK
W
MAX buon
MIN buon
Increase buon
Decrease buon
Green LED
Bank of
Bypass
Vavle
R
W
BR
Y
BL
Gas
Propor-
onal
Valve
R
YO
BL
W
FM
IG
Igniter rod P
P
exchangerHeat
thermistor
Inlet thermistor
Outlet thermistor
Temperature remote controller
Parent
1
2
Flow
Sensor
Flow
Adjust-
ment
Valve
Heater
Heater
540 Outdoor
Heater
Y
Y
Heater
Y
Y
Heater
Heater
540 Direct Vent Indoor
Hi-
swich
limit
O.H.C.F
MV
SV1
SV2
SV3
BL
BL BL
BL
LB
G
O
R
BL
540 Direct Vent Indoor Only
540 Direct Vent Indoor Only
DIPswitches
B
I
H1
J1
E3
E2
E1
F
K1
K2
A
G
C
J
H2 D1D2
L
C1
C2 A1
A2
B1

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
7. Wiring diagram check points for diagnosis
The table below applies to both the the Direct Vent Indoor models and Outdoor models.
Check-
point Part and Description Color of wires Normal range
A120V Power supply White – Black 108 to 132 VAC
A1, A2 120V Power supply Black - White 108 to 132 VAC
BIgniter Purple - Purple 108 to 132 VAC
B1 Heater Yellow - Yellow 108 to 132 VAC
CGas valves
Light blue - blue at COM (MV) 93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Green - blue at COM (SV1) 93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Orange - blue at COM (SV2) 93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Red - blue at COM (SV3) 93 to 120 VDC (during
operation) / 2.07 to 2.53 kΩ
C1 Hi-limit switch Blue - Blue
Less than 1 VDC
and
less than 1.0 Ω
C2 Overheat cutoff fuse Blue - Blue
Less than 1 VDC
and
less than 1.0 Ω
D1, D2 Easy-link connectors
540 (T-H3) models only Black - White 15 VDC (during Easy-link operation)
E1 Outlet thermistor Black - Black
See table on p. 18
E2 Inlet thermistor Black - Black
E3 Heat exchanger thermistor
540 (T-H3) models only Black - Black See table on p. 19

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
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CONFIDENTIAL
Check-
point Part and Description Color of wires Normal range
FRemote controller White – Black 11 to 25 VDC
GFan motor
Red - Blue 132 to 192 VDC
Yellow - Blue 13 to 17 VDC
Orange - Blue 2.0 to 6.5 VDC
H1 Gas proportional valve White - red
1.0 to 15 VDC
(during operation)
and
20 to 40 Ω
H2 Flow sensor
Red - Black 4.0 to 5.5 VDC
White - Black
1.0 to 4.0 VDC (pulse)
1,080 pulse / min
(more than 18 Hz)
I
Air-fuel ratio rod
Yellow - AFR rod
(Between the AFR rod and
the computer board)
More than 1 μA
(during operation)
Flame rod
Orange - Flame rod
(Between the flame rod and
the computer board)
More than 1 μA
(during operation)
J Flow adjustment valve Red - Black 7.0 to 16 VDC and
0.09 to 0.2 kΩ
J1 Bypass valve
540 (T-H3) models only Brown - Red 3.0 to 11 VDC and 50 to 85 Ω
K1 Exhaust thermisator White - White See table on p. 19
K2 Hi-limit switch for exhaust White - White
Less than 1 VDC
and
less than 1.0 Ω
LTemperature controller White – Black 11 to 25 VDC

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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
8. (A) Resistance values of the temperature thermistors
The the Direct Vent Indoor models and Outdoor models use the same thermistors.
Temperature (°F) vs Resisitance (kΩ)
Temperature (°C) vs Resisitance (kΩ)
0.00
5.00
10.00
15.00
20.00
25.00
20 40 60 80 100 120 140 160 180 200 220
Resisitance / kΩ
Temperature / ºF
0.00
5.00
10.00
15.00
20.00
25.00
0 10 20 30 40 50 60 70 80 90 100
Resisitance / kΩ
Temperature / ºC
Resisitance values at different temperatures
Temperature °F 32 41 50 59 68 77 86 95 104 113
°C 0 5 10 15 20 25 30 35 40 45
Resistance kΩ 23.76 19.08 15.43 12.56 10.28 8.47 7.02 5.85 4.90 4.12
Temperature °F 122 131 140 149 158 167 176 185 194 203 212
°C 50 55 60 65 70 75 80 85 90 95 100
Resistance kΩ 3.49 2.96 2.53 2.16 1.86 1.60 1.39 1.21 1.05 0.92 0.81

19 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
8. (B) Resistance values of the temperature exhaust thermistor
Only the Direct Vent Indoor models are equipped with the exhaust thermistor.
Temperature (°F) vs Resisitance (kΩ)
Temperature (°C) vs Resisitance (kΩ)
Resisitance values at different temperatures
Temperature °F 32 41 50 59 68 77 86 95 104 113
°C 0 5 10 15 20 25 30 35 40 45
Resistance kΩ 30.04 24.12 19.50 15.87 13.00 10.71 8.87 7.39 6.19 5.21
Temperature °F 122 131 140 149 158 167 176 185 194 203 212
°C 50 55 60 65 70 75 80 85 90 95 100
Resistance kΩ 4.41 3.74 3.19 2.73 2.35 2.03 1.76 1.53 1.33 1.16 1.02

20 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
9. Operational flow chart
The diagram below refers to both the Direct Vent Indoor models and Outdoor models.
Power supply ON
Operaon SW ON
FAV&BV open
Pre-check
NORMAL?
Faucet opens
Water Flow
Above 0.5GPM?
FM speed
(Below
1,000rpm?)
Fan moter start
operaon
Flame rod
DC0.15μA?
Igniter ON
Hi-limit
Normal?
OHCF
Normal?
MV ON
SV2 ON
GPV ON
Flame rod
detects Above
DC1.0μA?
Burning lamp ON
Igniter OFF
Proporonal control
BTU
change over
point?
SV1 SV3 ON
Below water
heat capability?
FAV OPEN
Safety devices
sensed
abnormal condion
FAV close
SV1 SV3 OFF
False Dipswitch sengs
InTH failure
PCB failure
MV circuit failure
031 blink
321 blink
701 or 771 blink
510 blink
611 blink
Fan motor stop
operaon
721 blink
False flame
Igniter OFF
Reignion
Success?
MV OFF
SV2 OFF
GPV OFF
SV1 SV3 OFF
Fan motor stop operaon
Faucet closes
Flow sensor OFF
Remove cause
Opearon lamp OFF
Operaon 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
restricon?
111 blink
121 blink
341 blink
311 blink
OuTH failure 311 blink
OuTH failure 331 blink
Flame
blows out
OHCF melted
(above 430゜
F)
AFR rod
failure Abnormal
burning
121 blink
121 blink
991 blink
391 blink
BV modulates
Flow&temp
321 blink
InTH OPEN
or SHORT
331 blink
OuTH OPEN
or SHORT
detects Below
FAV ; Flow Adjustment Valve
B V ; Bypass Valve
F M ; Fan Motor
OHCF; Over Heat Cut-off Fuse
M V ; Main gas Valve
SV1 ; Solenoid Valve 1 (See the secon 6)
SV2 ; Solenoid Valve 2 (See the secon 6)
SV3 ; Solenoid Valve 3 (See the secon 6)
GPV ; Gas Proporonal Valve
InTH; Inlet thermistor
OuTH; Outlet thermistor
Heat exchangerTH; Heat exchanger thermistor
Exhaust TH; Exhaust thermistor
PCB ; Print Circuit board
(Computer board)
AFR ; Air Fuel Rao rod
(Only 540 (T-H3) models)
(Only 240 (T-H3J) / 240 (T-H3S) models)
PCB
failure
711 blink
Exhaust
temp. failure
941 blink
*
SV circuit failure 551 blink
Thermistor or HL switch
for exhaust gas failure
941 blink
Fault of flow adjustmentvalve 651 blink
*NOTE
The "341" and "941" error code are
enabled in the Direct Vent Indoor models.
Heat exchanger TH failure
(Only 540 (T-H3) models)
ExhaustTH failure 341 blink
Fan motor
fault
611 blink
OuTH OPEN or SHORT
(Only 240 (T-H3J) / 240 (T-H3S) models)
Heat exchanger TH OPEN
(Only 540 (T-H3) models)
ExhaustTH
OPEN or SHORT
*
(Only 540 (T-H3) models)
(Only Easy-link system)
Fault of
bypass valve
661 blink
(Only 540 (T-H3) models)
or SHORT