A.O. Smith 240 T-H3J 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
TRGSM00713

2Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
Table of Contents
പϭ^ƉĞĐŝĨŝĐĂƚŝŽŶƐ
പϮdžƚĞƌŝŽƌǀŝĞǁ
പϯ/ŶƚĞƌŝŽƌǀŝĞǁ
പϰ>ŝƐƚŽĨŵĂŝŶĐŽŵƉŽŶĞŶƚƐŝŶƚŚĞŝŶƚĞƌŝŽƌǀŝĞǁ
ϱ^ĐŚĞŵĂƟĐĚŝĂŐƌĂŵ.
6. Wiring diagram.................................................................................................................
ϳtŝƌŝŶŐĚŝĂŐƌĂŵĐŚĞĐŬƉŽŝŶƚƐĨŽƌĚŝĂŐŶŽƐŝƐ
ϴ;ͿZĞƐŝƐƚĂŶĐĞǀĂůƵĞƐŽĨƚŚĞƚĞŵƉĞƌĂƚƵƌĞƚŚĞƌŵŝƐƚŽƌƐ
ϴ;ͿZĞƐŝƐƚĂŶĐĞǀĂůƵĞƐŽĨƚŚĞƚĞŵƉĞƌĂƚƵƌĞĞdžŚĂƵƐƚƚŚĞƌŵŝƐƚŽƌƐ
ϵKƉĞƌĂƟŽŶĂůŇŽǁĐŚĂƌƚ
ϭϬŽŵƉŽŶĞŶƚƐƉĞĐŝĮĐĂƟŽŶƐ
ϭϭ&ĂƵůƚŶĂůLJƐŝƐΘ^ƉĞĐŝĮĐĂƟŽŶƐ
ϭϮŽŶƚƌŽůƐĂŶĚƐĞƫŶŐƐ
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 ,ϮϮϰdžtϭϳϳdžϭϬϳ
ϱϳϬ;,ͿdžϰϱϬ;tͿdžϮϳϮ;Ϳ
mm
Weight lbs. (kg) 58 (26.3) 58 (26.2) 58 (26.3) 58 (26.2) 58 (26.8) 58 (26.9)
Combustion
/EWhd
dhŚ
DĂdž 160,000 180,000 199,000
Min Propane 13,000
Natural gas 15,000
Combustion
system
/ŶƐƚĂůůĂƚŝŽŶ
Power vent
/ŶƐƚĂůůĂƚŝŽŶ Direct-vent
/ŶĚŽŽƌ Outdoor Direct-vent /ŶĚŽŽƌ Outdoor Direct-vent /ŶĚŽŽƌ Outdoor
Fan motor WtDƚƵƌďŽĨĂŶ
DĂŶŝĨŽůĚ
Pressure*
("W.C.)
DĂdž 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)
ĚĞĨĂƵůƚϭϮϬ;ϰϵͿ
100 to 185 (38 to 85)
ĚĞĨĂƵůƚϭϮϬ;ϰϵͿ
Temperature
/WƐǁŝƚĐŚ
settings
°F
(°C) 120 (49), 140 (60)
Bypass valve E Yes
Thermistors ϮƚŚĞƌŵŝƐƚŽƌƐ;/ŶKƵƚͿ 3 thermistors
;/ŶKƵƚ,ĞĂƚĞdžĐŚĂŶŐĞƌͿ
Operation
Temperature
control
dĞŵƉĞƌĂƚƵƌĞĐŽŶƚƌŽůůĞƌŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐ
dĞŵƉĞƌĂƚƵƌĞƌĞŵŽƚĞĐŽŶƚƌŽůůĞƌ;dDͲZϰϬͿKƵƚĚŽŽƌŵŽĚĞůƐ
PCB model 240
WĂƌƚηϯϭϵϭϰϯͲϱϰϯ;<ϭϴϲ)
340
WĂƌƚηϯϭϵϭϰϯͲϱϰϰ;<ϭϳϱͿ
540
WĂƌƚηϯϭϵϭϰϯͲϱϰϱ;<ϭϳϲͿ
/ŶĚŝĐĂƚŽƌƐ ^ƚĂŶĚͲďLJ>
Power supply
control Surge absorber & Power ON-OFF switch
Features
Freeze
protection
Ceramic heaters (All models) and
ƵƚŽͲĨŝƌŝŶŐƐLJƐƚĞŵ;KŶůLJϱϰϬŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐ;dͲ,ϯͲsͿŵŽĚĞůƐͿ
^ĞůĨͲ
combustion
improvement
Air-Fuel Ratio Detection System
ĂƐLJͲ>ŝŶŬ
system E zĞƐ;hƉƚŽϰƵŶŝƚƐͿ
Multiple-
system E zĞƐ;hƉƚŽϮϬƵŶŝƚƐͿ
ΎdŚĞŵĂŶŝĨŽůĚƉƌĞƐƐƵƌĞŵĞĂƐƵƌĞŵĞŶƚŝƐďĂƐĞĚŽŶĐŽŶĚŝƚŝŽŶƐǁŝƚŚŽƵƚĨƌŽŶƚĐŽǀĞƌ

4Page
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

5Page
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

6Page
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

7Page
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

8Page
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

9Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
540 Outdoor (T-H3-OS)
1
2
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5
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78 9
10
11
12
13
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15
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19
20
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24
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35
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36
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39
32
32
REMOTE
CONTROLLER
AC120V
OFF ON

10 Page
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
/ŶĚŽŽƌ
models 001
E <ϭϱϵ
Outdoor
models E <ϭϲϰ
2.
DĂŶŝĨŽůĚ
assembly with
gas valve
assembly
>WŵŽĚĞů
102
319143-515 <ϭϴϭ
NA model 319143-516 <ϭϴϮ
3. Computer board 701
319143-543
(240 models)
<ϭϴϲ
(T-H3J models)
319143-544
(340 models)
<ϭϳϱ
(T-H3S models)
319143-545
(540 models)
<ϭϳϲ
(T-H3 models)
4. /ŐŶŝƚĞƌ 711 319143-479 <ϭϱϯ
5. Gas valve
assembly
>WŵŽĚĞů /ŶĐůƵĚĞĚŝŶ
#102
319143-515 <ϭϴϭ
NA model 319143-516 <ϭϴϮ
6. Water inlet 404 319143-193 <<ϭh
7. Water outlet 409 319143-530 <ϮϬϴ
8. /ŶůĞƚƚŚĞƌŵŝƐƚŽƌ 407
319143-214
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<<ϰ:
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-465
(540 models)
<ϭϯϳ
(T-H3 models)
9. Outlet thermistor 408
319143-529
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϮϬϳ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-190
(540 models)
<<ϭ
(T-H3 models)
10. KǀĞƌŚĞĂƚĐƵƚͲŽĨĨĨƵƐĞ 413 319143-149 <ϯϯϯ
11. Burner assembly 101 319143-514 <ϭϵϮ
12. Hi-limit switch 412
319143-228
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
DϮϭϮ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-095
(540 models)
<Eϯϰ
(T-H3 models)

11 Page
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
/ŶĚŽŽƌ
models 103
319143-443 <ϭϬϵ
Outdoor
models 319143-043 <<Ϯϱ
14.
Freeze
protection
thermostat
/ŶĚŽŽƌ
models 713
319143-496 <ϭϴϰ
Outdoor
models 319143-497 <ϭϴϱ
15. Flow sensor 402 319143-463 <ϭϮϵ
16.
Primary heat
ĞdžĐŚĂŶŐĞƌ
assembly
/ŶĚŽŽƌ
models
401
319143-525
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϴ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-527
(540 models)
<ϮϬϬ
(T-H3 models)
Outdoor
models
319143-526
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϵ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-528
(540 models)
<ϮϬϲ
(T-H3 models)
17.
Secondary heat
ĞdžĐŚĂŶŐĞƌ
assembly
/ŶĚŽŽƌ
models
/ŶĐůƵĚĞĚŝŶ
#401
319143-525
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϴ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-527
(540 models)
<ϮϬϬ
(T-H3 models)
Outdoor
models
319143-526
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϵ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-528
(540 models)
<ϮϬϲ
(T-H3 models)
18. Gas inlet 118 319143-455 <ϭϭϳ
19. Flow adjustment valve 402 319143-463 <ϭϮϵ
20. ^ƵƌŐĞďŽdž 703 320273-128 <ϮϴϬ
21. Outlet drain plug 410 319143-199 <<Ϯ
22. AFR rod 108 319143-517 <ϭϵϯ
23. Flame rod 108 319143-517 <ϭϵϯ
24. /ŐŶŝƚĞƌƌŽĚ 109 319143-037 <<Ϭ&
25. /ŶůĞƚĚƌĂŝŶƉůƵŐ
;ǁĂƚĞƌĨŝůƚĞƌͿ 405 319143-197 <<Ϯ
26. 120 VAC
Power ON-OFF switch 706 319143-141 <<ϰs

12 Page
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. DĂŶŝĨŽůĚƉŽƌƚ E E E
28. Gas inlet port E E E
29. džŚĂƵƐƚ
chamber
/ŶĚŽŽƌ
models
/ŶĐůƵĚĞĚŝŶ
#401
319143-525
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϴ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-527
(540 models)
<ϮϬϬ
(T-H3 models)
Outdoor
models
319143-526
;ϮϰϬϯϰϬŵŽĚĞůƐͿ
<ϭϵϵ
;dͲ,ϯ:dͲ,ϯ^ŵŽĚĞůƐͿ
319143-528
(540 models)
<ϮϬϲ
(T-H3 models)
30. ^ĞĐŽŶĚĂƌLJŚĞĂƚĞdžĐŚĂŶŐĞƌ
drain plug 411 319143-096 <<Ϯd
31. Pipe heater 414 319143-531 <ϮϬϵ
32. /ŶůĞƚKƵƚůĞƚŚĞĂƚĞƌ 417 319143-468 <ϭϬϱ
33. Block heaters
/ŶĚŽŽƌ
models 415
319143-532 <ϮϭϬ
Outdoor
models 319143-533 <Ϯϭϭ
34. Flat heater 464 319143-535 <Ϯϭϳ
35. ,ĞĂƚĞdžĐŚĂŶŐĞƌƚŚĞƌŵŝƐƚŽƌ 411 319143-096 <<Ϯd
36. Bypass valve 403 319143-464 <ϱϴ
37. ,ŝͲ>ŝŵŝƚƐǁŝƚĐŚĨŽƌĞdžŚĂƵƐƚ 472 319143-104 <,ϲ'
38. džŚĂƵƐƚƚŚĞƌŵŝƐƚŽƌ 471 319143-111 yϭϯ>
39. Condensate drain port 009 319143-018 <,Ϯϯ

13 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
5. Schematic diagram
dŚĞĚŝĂŐƌĂŵďĞůŽǁƌĞĨĞƌƐƚŽďŽƚŚƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĂŶĚKƵƚĚŽŽƌŵŽĚĞůƐ
1. When a hot water tap is opened, cold water enters the water heater.
ϮdŚĞǁĂƚĞƌĨůŽǁƐĞŶƐŽƌĚĞƚĞĐƚƐƚŚŝƐǁĂƚĞƌĨůŽǁĂŶĚƐĞŶĚƐƚŚŝƐŝŶĨŽƌŵĂƚŝŽŶƚŽĐŽŵƉƵƚĞƌ
ϯdŚĞĐŽŵƉƵƚĞƌŝŶŝƚŝĂƚĞƐĨĂŶŵŽƚŽƌĂŶĚƐĞŶĚƐƐŝŐŶĂůƚŽŝŐŶŝƚĞƌƚŽĐƌĞĂƚĞŝŐŶŝƚŝŽŶƐƉĂƌŬ
4. The main, proportional, and solenoid gas valves open to allow gas input.
ϱdŚĞŐĂƐŝŐŶŝƚĞƐĂŶĚĨůĂŵĞƐĂƉƉĞĂƌŝŶƐŝĚĞƚŚĞďƵƌŶĞƌĐŚĂŵďĞƌ
ϲtĂƚĞƌĐŝƌĐƵůĂƚĞƐƚŚƌŽƵŐŚƚŚĞŚĞĂƚĞdžĐŚĂŶŐĞƌĂŶĚŝƐŚĞĂƚĞĚƵƉƚŽƚŚĞƐĞƚƚĞŵƉĞƌĂƚƵƌĞ
ϳhƐŝŶŐƚŚĞƌŵŝƐƚŽƌƐƚŽŵĞĂƐƵƌĞƚĞŵƉĞƌĂƚƵƌĞƐƚŚĞĐŽŵƉƵƚĞƌŵŽĚƵůĂƚĞƐƚŚĞŐĂƐĂŶĚǁĂƚĞƌǀĂůǀĞƐƚŽ
ensure proper output water temperatures.
8. When the tap is closed, the water heater shuts down.
dŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĚĞƚĞĐƚƐƚŚĞĞdžŚĂƵƐƚƚĞŵƉĞƌĂƚƵƌĞďLJƵƐŝŶŐ
ĞdžŚĂƵƐƚƚŚĞƌŵŝƐƚŽƌĂŶĚŚŝͲůŝŵŝƚƐǁŝƚĐŚĨŽƌĞdžŚĂƵƐƚĚƵƌŝŶŐƉƌŽĐĞĚƵƌĞƐŽĨϯƚŽϴ
NOTICE
HOT COLD
GAS
Hi-limit switch
Inlet drain
ƉůƵŐĮůƚĞƌ
Outlet thermistor
Drain plug
Main gas valve
Gas solenoid valve 2
&ĂŶŵŽƚŽƌĨŽƌĐŽŵďƵƐƟŽŶ
Igniter
O.H.C.F
Flow adjustment valve
with Flow sensor
'ĂƐƉƌŽƉŽƌƟŽŶĂůǀĂůǀĞ
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
ŝƌͲĨƵĞůƌĂƟŽƌŽĚ
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-
ƟŽŶĂů
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
ĞĐƌĞĂƐĞďƵƩŽŶ
/ŶĐƌĞĂƐĞďƵƩŽŶ
D/EďƵƩŽŶ
DyďƵƩŽŶ
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
DyďƵƩŽŶ
D/EďƵƩŽŶ
/ŶĐƌĞĂƐĞďƵƩŽŶ
ĞĐƌĞĂƐĞďƵƩŽŶ
Green LED
Bank of
Bypass
Vavle
R
W
BR
Y
BL
Gas
Propor-
ƟŽŶĂů
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
YHeater
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

16 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
7. Wiring diagram check points for diagnosis
dŚĞƚĂďůĞďĞůŽǁĂƉƉůŝĞƐƚŽďŽƚŚƚŚĞƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĂŶĚKƵƚĚŽŽƌŵŽĚĞůƐ
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
B/ŐŶŝƚĞƌ Purple - Purple 108 to 132 VAC
B1 Heater Yellow - Yellow 108 to 132 VAC
CGas valves
>ŝŐŚƚďůƵĞͲďůƵĞĂƚKD;DsͿ 93 to 120 VDC (during
ŽƉĞƌĂƚŝŽŶͿϭϯϱƚŽϭϲϱŬɏ
Green - blue at COM (SV1) 93 to 120 VDC (during
ŽƉĞƌĂƚŝŽŶͿϭϯϱƚŽϭϲϱŬɏ
Orange - blue at COM (SV2) 93 to 120 VDC (during
ŽƉĞƌĂƚŝŽŶͿϭϯϱƚŽϭϲϱŬɏ
Red - blue at COM (SV3) 93 to 120 VDC (during
ŽƉĞƌĂƚŝŽŶͿϮϬϳƚŽϮϱϯŬɏ
C1 Hi-limit switch Blue - Blue
>ĞƐƐƚŚĂŶϭs
and
ůĞƐƐƚŚĂŶϭϬɏ
C2 KǀĞƌŚĞĂƚĐƵƚŽĨĨĨƵƐĞ Blue - Blue
>ĞƐƐƚŚĂŶϭs
and
ůĞƐƐƚŚĂŶϭϬɏ
D1, D2 ĂƐLJͲůŝŶŬĐŽŶŶĞĐƚŽƌƐ
540 (T-H3) models only Black - White 15 VDC ;ĚƵƌŝŶŐĂƐLJͲůŝŶŬŽƉĞƌĂƚŝŽŶͿ
E1 Outlet thermistor Black - Black
See table on p. 18
E2 /ŶůĞƚƚŚĞƌŵŝƐƚŽƌ Black - Black
E3 ,ĞĂƚĞdžĐŚĂŶŐĞƌƚŚĞƌŵŝƐƚŽƌ
540 (T-H3) models only Black - Black See table on p. 19

17 Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
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
ϮϬƚŽϰϬɏ
H2 Flow sensor
Red - Black 4.0 to 5.5 VDC
White - Black
1.0 to 4.0 VDC (pulse)
ϭϬϴϬƉƵůƐĞŵŝŶ
(more than 18 Hz)
I
ŝƌͲĨƵĞůƌĂƚŝŽƌŽĚ
Yellow - AFR rod
(Between the AFR rod and
the computer board)
DŽƌĞƚŚĂŶϭʅ
(during operation)
Flame rod
Orange - Flame rod
;ĞƚǁĞĞŶƚŚĞĨůĂŵĞƌŽĚĂŶĚ
the computer board)
DŽƌĞƚŚĂŶϭʅ
(during operation)
JFlow adjustment valve Red - Black 7.0 to 16 VDC and
ϬϬϵƚŽϬϮŬɏ
J1 Bypass valve
540 (T-H3) models only Brown - Red 3.0 to 11 VDC and ϱϬƚŽϴϱɏ
K1 džŚĂƵƐƚƚŚĞƌŵŝƐĂƚŽƌ White - White See table on p. 19
K2 ,ŝͲůŝŵŝƚƐǁŝƚĐŚĨŽƌĞdžŚĂƵƐƚ White - White
>ĞƐƐƚŚĂŶϭs
and
ůĞƐƐƚŚĂŶϭϬɏ
LTemperature controller White – Black 11 to 25 VDC

18 Page
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
dŚĞƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĂŶĚKƵƚĚŽŽƌŵŽĚĞůƐƵƐĞƚŚĞƐĂŵĞƚŚĞƌŵŝƐƚŽƌƐ
Temperature (°FͿǀƐZĞƐŝƐŝƚĂŶĐĞ;Ŭɏ)
Temperature (°CͿǀƐZĞƐŝƐŝƚĂŶĐĞ;Ŭɏ)
0.00
5.00
10.00
15.00
20.00
25.00
20 40 60 80 100 120 140 160 180 200 220
Resisitance / kȍ
Temperature /ºF
0.00
5.00
10.00
15.00
20.00
25.00
0 102030405060708090100
Resisitance / kȍ
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 Ŭɏ 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 Ŭɏ 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
KŶůLJƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĂƌĞĞƋƵŝƉƉĞĚǁŝƚŚƚŚĞĞdžŚĂƵƐƚƚŚĞƌŵŝƐƚŽƌ
Temperature (°FͿǀƐZĞƐŝƐŝƚĂŶĐĞ;Ŭɏ)
Temperature (°CͿǀƐZĞƐŝƐŝƚĂŶĐĞ;Ŭɏ)
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 Ŭɏ 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 Ŭɏ 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
dŚĞĚŝĂŐƌĂŵďĞůŽǁƌĞĨĞƌƐƚŽďŽƚŚƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐĂŶĚKƵƚĚŽŽƌŵŽĚĞůƐ
Power supply ON
KƉĞƌĂƟŽŶ^tKE
&sΘsŽƉĞŶ
Pre-check
NORMAL?
&ĂƵĐĞƚŽƉĞŶƐ
tĂƚĞƌ&ůŽǁ
Above 0.5GPM?
FM speed
(Below
1,000rpm?)
&ĂŶŵŽƚĞƌƐƚĂƌƚ
ŽƉĞƌĂƟŽŶ
Flame rod
DC0.15ʅA?
/ŐŶŝƚĞƌKE
,ŝͲůŝŵŝƚ
Normal?
OHCF
Normal?
MV ON
^sϮKE
GPV ON
Flame rod
detects Above
DC1.0ʅA?
ƵƌŶŝŶŐůĂŵƉKE
/ŐŶŝƚĞƌK&&
WƌŽƉŽƌƟŽŶĂůĐŽŶƚƌŽů
BTU
ĐŚĂŶŐĞŽǀĞƌ
ƉŽŝŶƚ
^sϭ^sϯKE
Below water
ŚĞĂƚĐĂƉĂďŝůŝƚLJ
FAV OPEN
^ĂĨĞƚLJĚĞǀŝĐĞƐ
ƐĞŶƐĞĚ
ĂďŶŽƌŵĂůĐŽŶĚŝƟŽŶ
FAV close
^sϭ^sϯK&&
&ĂůƐĞŝƉƐǁŝƚĐŚƐĞƫŶŐƐ
/Ŷd,ĨĂŝůƵƌĞ
WĨĂŝůƵƌĞ
DsĐŝƌĐƵŝƚĨĂŝůƵƌĞ
ϬϯϭďůŝŶŬ
ϯϮϭďůŝŶŬ
ϳϬϭŽƌϳϳϭďůŝŶŬ
ϱϭϬďůŝŶŬ
ϲϭϭďůŝŶŬ
&ĂŶŵŽƚŽƌƐƚŽƉ
ŽƉĞƌĂƟŽŶ
ϳϮϭďůŝŶŬ
&ĂůƐĞŇĂŵĞ
/ŐŶŝƚĞƌK&&
ZĞŝŐŶŝƟŽŶ
^ƵĐĐĞƐƐ
MV OFF
^sϮK&&
GPV OFF
^sϭ^sϯK&&
&ĂŶŵŽƚŽƌƐƚŽƉŽƉĞƌĂƟŽŶ
Faucet closes
&ůŽǁƐĞŶƐŽƌK&&
Remove cause
KƉĞĂƌƟŽŶůĂŵƉK&&
KƉĞƌĂƟŽŶƐƚŽƉ
z^
NO
z^
NO
NO
z^
z^
NO
;ϮϬƐĞĐůĂƚĞƌͿ
z^
NO
NO
z^
z^
NO
z^
NO
(5sec later)
z^
z^
NO
z^
NO
;ϮϬƐĞĐůĂƚĞƌͿ
z^
NO
NO
NO
z^
FM speed
(Above
1,000rpm?)
Below
DĂdžŇŽǁƌĂƚĞ
ƌĞƐƚƌŝĐƟŽŶ
ϭϭϭďůŝŶŬ
ϭϮϭďůŝŶŬ
ϯϰϭďůŝŶŬ
ϯϭϭďůŝŶŬ
KƵd,ĨĂŝůƵƌĞ ϯϭϭďůŝŶŬ
KƵd,ĨĂŝůƵƌĞ ϯϯϭďůŝŶŬ
Flame
blows out
OHCF melted
;ĂďŽǀĞϰϯϬ゜
F)
AFR rod
ĨĂŝůƵƌĞ ďŶŽƌŵĂů
ďƵƌŶŝŶŐ
ϭϮϭďůŝŶŬ
ϭϮϭďůŝŶŬ
ϵϵϭďůŝŶŬ
ϯϵϭďůŝŶŬ
BV modulates
Flow&temp
ϯϮϭďůŝŶŬ
/Ŷd,KWE
Žƌ^,KZd
ϯϯϭďůŝŶŬ
OuTH OPEN
Žƌ^,KZd
detects Below
&s&ůŽǁĚũƵƐƚŵĞŶƚsĂůǀĞ
B V ; Bypass Valve
&D&ĂŶDŽƚŽƌ
K,&KǀĞƌ,ĞĂƚƵƚͲŽī&ƵƐĞ
DsDĂŝŶŐĂƐsĂůǀĞ
^sϭ^ŽůĞŶŽŝĚsĂůǀĞϭ;^ĞĞƚŚĞƐĞĐƟŽŶϲͿ
^sϮ^ŽůĞŶŽŝĚsĂůǀĞϮ;^ĞĞƚŚĞƐĞĐƟŽŶϲͿ
^sϯ^ŽůĞŶŽŝĚsĂůǀĞϯ;^ĞĞƚŚĞƐĞĐƟŽŶϲͿ
'Ws'ĂƐWƌŽƉŽƌƟŽŶĂůsĂůǀĞ
/Ŷd,/ŶůĞƚƚŚĞƌŵŝƐƚŽƌ
KƵd,KƵƚůĞƚƚŚĞƌŵŝƐƚŽƌ
,ĞĂƚĞdžĐŚĂŶŐĞƌd,,ĞĂƚĞdžĐŚĂŶŐĞƌƚŚĞƌŵŝƐƚŽƌ
džŚĂƵƐƚd,džŚĂƵƐƚƚŚĞƌŵŝƐƚŽƌ
WWƌŝŶƚŝƌĐƵŝƚďŽĂƌĚ
(Computer board)
&Zŝƌ&ƵĞůZĂƟŽƌŽĚ
;KŶůLJϱϰϬ;dͲ,ϯͿŵŽĚĞůƐͿ
;KŶůLJϮϰϬ;dͲ,ϯ:ͿϮϰϬ;dͲ,ϯ^ͿŵŽĚĞůƐͿ
PCB
ĨĂŝůƵƌĞ
ϳϭϭďůŝŶŬ
Exhaust
ƚĞŵƉĨĂŝůƵƌĞ
ϵϰϭďůŝŶŬ
*
^sĐŝƌĐƵŝƚĨĂŝůƵƌĞ ϱϱϭďůŝŶŬ
dŚĞƌŵŝƐƚŽƌŽƌ,>ƐǁŝƚĐŚ
ĨŽƌĞdžŚĂƵƐƚŐĂƐĨĂŝůƵƌĞ
ϵϰϭďůŝŶŬ
&ĂƵůƚŽĨŇŽǁĂĚũƵƐƚŵĞŶƚvalve ϲϱϭďůŝŶŬ
*NOTE
dŚĞΗϯϰϭΗĂŶĚΗϵϰϭΗĞƌƌŽƌĐŽĚĞĂƌĞ
ĞŶĂďůĞĚŝŶƚŚĞŝƌĞĐƚsĞŶƚ/ŶĚŽŽƌŵŽĚĞůƐ
,ĞĂƚĞdžĐŚĂŶŐĞƌd,ĨĂŝůƵƌĞ
;KŶůLJϱϰϬ;dͲ,ϯͿŵŽĚĞůƐͿ
džŚĂƵƐƚd,ĨĂŝůƵƌĞ ϯϰϭďůŝŶŬ
&ĂŶŵŽƚŽƌ
ĨĂƵůƚ
ϲϭϭďůŝŶŬ
KƵd,KWEŽƌ^,KZd
;KŶůLJϮϰϬ;dͲ,ϯ:ͿϮϰϬ;dͲ,ϯ^ͿŵŽĚĞůƐͿ
,ĞĂƚĞdžĐŚĂŶŐĞƌd,KWE
;KŶůLJϱϰϬ;dͲ,ϯͿŵŽĚĞůƐͿ
ExhaustTH
KWEŽƌ^,KZd
*
;KŶůLJϱϰϬ;dͲ,ϯͿŵŽĚĞůƐͿ
;KŶůLJĂƐLJͲůŝŶŬƐLJƐƚĞŵͿ
&ĂƵůƚŽĨ
bypass valve
ϲϲϭďůŝŶŬ
;KŶůLJϱϰϬ;dͲ,ϯͿŵŽĚĞůƐͿ
Žƌ^,KZd