Troubleshooting Guide
Computer board
assembly
708
713
711
709
103
707
722
715
402
714
402
715
721
715
726
701
716
D. Components diagram / Parts list
002
050
050
717
052
008
052
067
704
702
001
004
002
717
004
052
052
003
419
007
713
052
725
001
702
006
005
052
Outdoor model
Indoor model
Case assembly
101
104
115
106
107
108
110
109
111
711
112
062
053
053
709
053
053
401
103
105
065
054
113
102
708
119
151
118
055
051
150
057
055
711
063
121
707
714
719
117
062
066
709
730
117
053
116
114
Burner assembly
Burner
assembly
Manifold
assembly
D
A
B
E
E
F
F
C
B
A
D
C
H
403
456
460
458
462
473
064
412
058
468
462
468
064
473
467
462
462
451
414
459
454
463
407
463
455
465
466
458
462
052
409
408
454
417
410
455
451
415
451
415
052
469
455
464
416
450
414
459
454
411
401
718
053
418
152
153
472
418
415
009
052
471
470
402
460
456
461
404
733
460
456
458
729
458
462
417
059
454
732
457
406
052
405
728
451
734
456
460
456
735
451
734
727
726
461
404
458
052
405
457
406
059
454
731
G
G
H
Water inlet secon
Pump secon
Water outlet secon
Bypass secon
461
458
419
067
413
453
452
Water way assembly
723
056
722
Built-in contoller
Indoor model
Surge box
121
713
706
703
Temperature
remote controller
724
Item
#
Part #
Description
540P T-H3P
053
054
055
056
057
100074245
100074510
100074248
N/A
100074385
EW003
EW004
EW005
EW018
EKK31
Truss screw M4x10 SUS
Hex head screw M4×12 (W/Washer) SUS3
Hex head screw M4x8 FEZN
Pan screw M4x20 SUS410
Tap tight screw M4x12 FEZN
058
059
060
061
100074272
100074512
100076269
N/A
EW00A
EW009
EKK37
EK191
Tapping screw M3x6 SUS3 Pan head
Tapping screw M4x6 SUS3 Truss head
Tap tight screw M4x12
Plus bind Screw M3x6 FEZN
062
063
064
065
100074244
100074233
N/A
100074514
EW00D
EM167
EK230
EW00B
Pan screw M4x8 MFZN
Wire clamp 60
Screw M4x10
Screw M3x6 SUS3 Binding head
066
067
100074247
N/A
EW006
EK739
Pan screw M4x10
Pan screw M4x10 for 3” adapter
Item
#
Part #
Description
540P T-H3P
114
115
100074230
100074217
EKK2K
EKK0G
Manifold gasket B
Burner holder gasket
116
117
118
100074227
100074528
100074616
EKK2D
EX019
EK117
Pressure port
Combustion chamber tube
Gas inlet
119
121
100074526
N/A
EX00D
EK618
Gas inlet ring
Surge box plate
150
151
152
153
100074533
100074242
100074678
100074679
EZP18
EK042
EK157
EK177
O-ring P18 NBR (Black)
O-ring P20 NBR (Black)
Silicon ring for Outdoor model
Exhaust port for Outdoor model
401 100276637 EK621 Primary heat exchanger assembly
402
403
404
405
406
100074624
100074625
100074377
100074381
100074382
EK129
EKD58
EKK1U
EKK2B
EKK2C
Flow adjustment valve / Flow sensor
Bypass valve
Water inlet
Inlet drain plug
Inlet water filter
407 100276682 EK641 Inlet thermistor
408 100074374 EKK1A Outlet thermistor
409
410
411
100074681
100074383
100074281
EK208
EKK2E
EKK2T
Water outlet
Outlet drain plug
Heat exchanger thermistor
412 100074280 EKN34 Hi-Limit switch
413
414
100074334
100074682
EK333
EK209
Overheat-cut-off fuse
Pipe heater
415 100074683
100074684
EK210
EK211
Inlet heater for Indoor model
Inlet heater for Outdoor model
416
417
100074685
100074629
EK231
EK105
Drain tube
Inlet heater
418
419
100074700
100074701
100310706
EK251
EK256
EK737
Secondary heat exchanger for Indoor model
Secondary heat exchanger for Outdoor model
3” PVC adapter
450
451
452
453
100074273
100074310
100074251
100074331
EKK27
EK031
EKK26
EK029
Pipe heater fixing plate
Heater fixing plate 16
Fuse fixing plate 18
Fuse fixing plate 14
Item
#
Part #
Description
540P T-H3P
454
455
456
457
100076303
100076305
100076306
100076307
EZM04
EZM06
EZM14
EZM15
O-ring P4 FKM
O-ring P6 FKM
O-ring P14 FKM
O-ring P15 FKM
458
459
460
461
100076308
100074282
100074290
100074410
EZM16
EKH30
EKK24
EM192
O-ring P16 FKM
Fastener “4-11”
Fastener “14-22”
Fastener “16A”
462
463
464
465
100074389
100074297
100074686
100276674
EKK39
EX12K
EK217
EK625
Fastener “16-25A”
Fastener “6-15”
Flat heater
Drain tube
466 100276640 EK624 Cold pipe
467
468
469
470
100074690
100074691
100074692
100074291
EK222
EK226
EK228
EX13H
Stainless heat exchanger out pipe
Header connection
Drain port
Thermistor fixing plate
471
472
473
100074296
100074289
100074693
EX13L
EKH6G
EK229
Exhaust thermistor gasket
Hi-limit switch for exhaust
Gasket
701 100276677 EK628 Computer board
702
703
704
100076470
100076100
100074601
EX00B
EK280
EK146
Rubber grommet
Surge box
120 VAC wire for Indoor model
706
707
708
100074326
100074650
N/A
EKK4V
EK165
EK633
120 VAC Power ON-OFF switch
Remote controller wire
Gas valve wire
709
711
N/A
100276678
EK634
EK630
Flame rod wire
Igniter assembly
713 N/A
N/A
EK631
EK636
Switch wire with thermostat for Indoor
for Outdoor
714
715
716
717
100074657
N/A
N/A
100074375
N/A
EK167
EK632
EK638
EKK1M
EX13C
Proportional gas valve wire
24V cables for Indoor model
for Outdoor model
Computer board cover
Cable clamp
718
719
721
722
723
100074316
100074644
100074659
100276680
N/A
EKH6E
EK152
EK180
EK639
EK629
Exhaust thermistor for Indoor model
Remote fixing plate
Exhaust Hi-limit switch wire
Temperature controller for Indoor model
Fixing plate
724
725
726
100276687
N/A
100276636
TM-RE43
EK619
EK620
Temperature remote controller
Pump fixing plate
Recirculation pump assembly
727
728
729
100276638
100276639
100276676
EK622
EK623
EK626
Pump inlet pipe
Pump outlet pipe
Pump connection
730
731
732
N/A
100276681
100276683
EK627
EK640
EK642
PCB fixing plate
Return thermistor
Closing plug
733
734
735
100276686
100076326
100076400
EK643
EK469
EM190
Three way connection
Heater
Fastner "12.7"
Item
#
Part #
Description
540P T-H3P
101
102
103
100074670
100074671
100074672
100074606
100074228
EK192
EK181
EK182
EK109
EKK25
Burner assembly
Manifold with gas valve assembly LP
Manifold with gas valve assembly NA
Fan motor for Indoor model
Fan motor for Outdoor model
104
105
106
107
100074216
100074466
100074218
100074219
EKK2X
EM381
EKK2V
EKK2W
Burner gasket
Fan damper for Indoor model
Burner window
Rod holder gasket
108
109
110
111
100074673
100074222
100074221
100074223
EK193
EKK0F
EKK32
EKN61
Flame rod
Igniter rod
Rod holder
Rod cap
112
113
100074674
100074675
100074229
EK183
EK169
EKK2Y
Burner damper LP
Burner damper NA
Manifold gasket A
Item
#
Part #
Description
540P T-H3P
001
N/A
N/A
EK617
EK635
Case assembly for Indoor model
for Outdoor model
002 100074665
100074666
EK158
EK174
Front cover for 540P Indoor (AT-H3P-DV)
for 540P Outdoor (AT-H3P-OS)
003
004
005
006
007
100074667
N/A
100074668
100276679
N/A
EK170
EK162
EK190
EK637
EK161
Intake air port assembly
Bracket
Junction box
Power supply cord assembly
Back guard panel
008
009
N/A
100074203
EK160
EKH23
Chamber fixing plate
Condensate drain port
050
051
052
100074210
100074509
100074211
EW000
EW001
EW002
Truss screw M4×12 (W/Washer) SUS410
Truss screw M4×10 (W/Washer) SUS410
Truss screw M4×10 (Coated) SUS3
E. DIP switch settings on the computer board
High altitude installation (Indoor)
0 to 2,000 ft
(0 to 610 m)
(DEFAULT)
2,000 to
3,000 ft
(611 to 914
m)
3,000 to
5,000 ft
(915 to 1,524
m)
5,000 to
7,500 ft
(1,525 to
2,286 m)
7,500 to
10,100 ft
(2,287 to
3,078 m)
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
High altitude installation (Outdoor)
0 to 2,000 ft
(0 to 610 m)
(DEFAULT)
2,000 to
4,000 ft
(611 to 1,219
m)
4,000 to
6,000 ft
(1,220 to
1,829 m)
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
Middle bank of DIP switches
Upper bank
of DIP switches
Lower bank of DIP switches
Setting
temperature
120 °F
(50 °C)
(DEFAULT)
140 °F
(60 °C)
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON
Pump operation for
freeze protection
Active
Inactive
(DEFAULT)
1 2 3 4
ON
1 2 3 4
ON
WARNING
• Turn off the power supply to the water heater before changing
the DIP switch settings.
• The dark squares indicate the correct DIP switch positions.
• Failure to observe these warnings could lead to carbon monoxide
poisoning, severe personal injury, or death.
Gas
(Factory setting)
LP Natural
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
Manual
pump operation
ON
OFF
(DEFAULT)
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
Vent length and vent type installation
3” venting
4” venting
Common
venting
(DEFAULT)
Two-pipe, Direct vent installations
Single vent pipe installations
5 to 20 ft
(1.5 to 6.1 m)
(DEFAULT)
21 to 40 ft
(6.2 to 12.2 m)
41 to 70 ft
(12.3 to 21.3 m)
5 to 45 ft
(1.5 to 13.7 m)
(DEFAULT)
46 to 70 ft
(13.8 to 21.3 m)
5 to 50 ft
(1.5 to 15.2 m)
(DEFAULT)
51 to 100 ft
(15.3 to 30.5 m)
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
1 2 3 4 5 6 7 8
ON
Easy-Link
System
Single unit
installation
Parent
(DEFAULT)
1 2 3 4 5 6
ON
1 2 3 4 5 6
ON