Takagi TK310UENG, TK110UING Maintance Manual

110U, 310U 200 series

P: PURPLE

G: GREEN

O: ORANGE

BR: BROWN

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6

7 8 9

10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

ON

1 2 3 4 5 6 7 8 9 10

OFF

1 2 3 4 5 6 7 8 9 10

Maintenance sheet

1W3010-1

A. Troubleshooting

If the error code is displayed on the built-in controller and/or the remote controller, refer to Section B.

<< It takes a long time to get hot water at the fixtures >>

• The time it takes to deliver hot water from the water heater to your fixtures depends on the
length of piping between the two. The longer the distance or the bigger the pipes, the longer
it will take to get hot water.

• If you would like to receive hot water to your fixtures more quickly, you may want to consider
a hot water recirculation system.

<< The water is not hot enough or turns cold and stays cold >>

• Compare the flow and temperature. Refer to the “Output temperature chart” in the
Installation manual.

• Check cross plumbing between cold water lines and hot water lines.

• Check if the gas supply valve is open fully, the gas line is sized properly, and the gas supply

pressure is within specified limits. Refer to the “Gas supply and gas pipe sizing” in the
Installation manual.

• Check the set temperature on the built-in controller (the remote controller, if it is installed*)
or the DIP switch setting. Refer to Section D.

• Refer to the “Water circuit” in this section.

<<The water is too hot>>

• Check the set temperature and lower.

<<The hot water is not available when a fixture is opened>>

• Refer to “Power supply circuit” and “Water circuit” in this section.

• Check if the gas supply valve is open fully, the gas line is sized properly, and the gas supply

pressure is within specified limits.

<<Fluctuation of hot water temperature>>

• Check if the filter on the cold water inlet is clogged (Part #406).

• Check if the gas line is sized properly and the supply gas pressure is within specified limits.

• Check for cross connection between cold water lines and hot water lines.

• Refer to “Water circuit” in this section.

<<Unit does not ignite when water goes through the water heater>>

• Refer to “Power supply circuit” and “Water circuit” in this section.

• Check if the inlet water temperature is too high. If it is too close to the set temperature, the

water heater won't activate.

• Is the gas supply turned on?

B. Error codes

031: Incorrect DIP switch setting

• Check the DIP switch settings on the PCB. Refer to Section D.

101: Warning for the “991” error code

• Check the gas type of the house (and/or the building). This model comes from the factory

set for natural gas. This model can be converted to propane by a qualified agent with the LP
Conversion Kit (100270585) that comes with the heater.

• Check for and remove any blockage in the venting system. Refer to “Venting instructions” in
the Installation manual.

• Check for proper distance between the intake air and exhaust terminals and other exhaust
gas terminals. Refer to “Venting instructions” in the Installation manual.

• Verify that the vent length is within max. limit. Refer to "Venting instructions" in the
Installation manual. Make sure the DIP switches are set for the correct vent length and
installation. Refer to section D.

• Check the altitude/elevation where the water heater is installed. Refer to the “High-altitude
function” in Section D for correct DIP switch settings.

• Check for any grease and/or dirt in the burner (Part #101) and the fan motor (Part #103),
especially if the water heater has been installed in a contaminated area.

• Check if there is dust and lint in the heat exchanger.

• Check the manifold pressure of the water heater. Refer to the rating plate or LP Conversion

label.

111: Ignition failure*

• Check the gas supply and inlet gas pressure.

• Check if the Hi-limit switch (Part #412) is functioning properly.

• Check for connection/breakage of wires (Part #008, 413, 708, 709), and/or soot on the flame

rod (Part #107). And then if the O.H.C.F (Part #008, or 413) has a breakage, consult the
manufacturer.

• Check if there is a buzzing spark ignition sound coming from the burner (Part #101) when
water heater prepares for combustion.

• Listen for the double “clunk” sound coming from the gas valve assembly (Part #102) when
water heater goes into combustion.

• (Only if no sparking and/or clunk sound) Check the voltage on each wire to gas valve
assembly (Part #102) and/or the igniter assembly (Part #711). Refer to “Appendix A” in
Section C.

*No sparking sound >>>>> Refer to #1 of “Appendix A” in Section C.
*No clunk sound >>>>> Refer to #2 of “Appendix A” in Section C.

• Check if there is water leaking from the heat exchanger (Part #401).

• Check if there is dust and lint in nozzles of the manifold (Part #102).

• Check the current on the flame rod (Part #107). Refer to #3 of “Appendix A” in Section C.

121: Loss of flame*

• Check the gas supply and inlet gas pressure.

• Check if the Hi-limit switch (Part #412) is functioning properly.

• Check for connection/breakage of wires (Part #008, 413, 708, 709), burn marks on the

computer board (Part #701), and/or soot on the flame rod (Part #107). And then if the O.H.C.F
(Part #008 or 413) has a breakage, consult the manufacturer.

• Check if there is water leaking from the heat exchanger (Part #401).

• Check if there is dust and lint in the nozzles of the manifold (Part #102).

• Check the current on the flame rod (Part #107). Refer to #3 of “Appendix A” in Section C.

<<The fan motor is still spinning after operation has stopped>>

• This is normal. After operation has stopped, the fan motor keeps running for 15 to 70 seconds in
order to re-ignite quickly, as well as purge all the exhaust gas out of the flue.

<<Abnormal sound from water heater>>

• An abnormal sound from the water heater is caused by insufficient air supply or incorrect installation.
The water heater needs more combustion air. Refer to the “101” error code in the section B.

<<Power supply circuit>>

• Check the power supply, and make sure that the water heater has 120 VAC.

• Is the power switch inside water heater turned on? (Part #706)

• Press the “ON/OFF” button of the built-in controller (the remote controller, if it is installed*) and

make sure that the STAND BY LED on the controller is lit. Run the water.

• Check if the green LED on the PCB (Part #701) of the water heater is lit. If so, the power supply circuit of
the water heater is under normal condition. Next, refer to “Water circuit” in this section.

• Check the fuse on the surge box (Part #703), and if it has a brown spot, need to replace it.

• If the green LED on the PCB (Part #701) isn’t lit, some electrical parts may be broken. Consult the

manufacturer.

<<Water circuit>>

• Turn on the power button on the built-in controller (the remote controller if it is installed*), and
then check if the STAND BY LED will light up.

• Open all hot water faucets, and make sure that there is enough water flow. This water heater
needs at least 0.5 GPM (1.9 L/m) water flow (at the default set temperature) to operate.

• Check for reverse connection and cross connection.

• Check to see if the filter on the cold water inlet is clogged or if there is sediment buildup in the

filter. (Part #406).

• Check if water ways in the water heater are frozen. If so, thaw them. Refer to the Installation
manual to protect your water heater from freezing.

• Check if the inlet water pressure is higher than 40 psi. If it’s lower than 40 psi, increase the pressure.

• Check for connections and breakage of wires (Part #402).

• Check if the motor drive of the flow adjustment valve (Part #402) is locked due to scale buildup,

and/or water leakage. If so, consult the manufacturer.

*If a remote controller is installed, it will take priority over the built-in controller.

311,321: Disconnected/short-circuited thermistor*

• Check for connection/breakage of wires and/or debris on the thermistor (Part #407, 408).

• Check the thermistor resistance. Refer to “Appendix D” in Section C.

391: Air-fuel ratio rod failure*

• Check for connection/breakage of wires (Part #709) and/or soot on the flame rod (Part #107).

510,551: Abnormal main gas solenoid valve and gas solenoid valve

• Check for connection/breakage of wires (Part #708) and/or burn marks on the computer board (Part #701).

• Reset power supply of the water heater.

• Check the voltage of each valve on the gas valve assembly (Part #102). Refer to “Appendix C” in Section C.

611: Fan motor fault*

• Check for connection/breakage of wires, dust buildup in the fan motor (Part #103) and/or burn
marks on the computer board (Part #701).

• Check to see if the fan motor connectors are frozen or corroded (Part #103).

• Check the voltage between the blue wire and each wire of the fan motor (Part #103). Refer to

“Appendix B” in Section C.

701: Computer board fault*

• Check for connection/breakage of wires (Part #714), and check the resistance between the white
wire and red wire. Refer to #2 in Appendix A of Section C.

• Check the outlet thermistor (Part #408) for proper readings as it may need to be cleaned.

711: Gas solenoid valve drive circuit failure*

• Refer to the “111” and “121” error codes in this section.

721: False flame detection*

• Clean the flame rod (Part #107).

• Check if a vertical condensation drain is installed on the vent collar of the water heater, if there is

more than 5 ft. (1.5 m) of straight pipe.

• Check if there is water leaking from the heat exchanger (Part #401).

741: Miscommunication between water heater and remote controller

• This error code will appear if the remote controller is disconnected from the PCB while power is still on.

• Check the model type of the remote controller. Model No. 100209924 (TM-RE42)

• Inspect the connections between the water heater and remote controller. Refer to the

“Temperature Remote Controller” in the Installation manual.

• Check the power supply to the water heater.

• If this error code appears only on the green LED on the PCB (Part #701), check the voltage on the

remote controller terminal on the PCB. Refer to “Appendix E” in Section C.

• If this error code appears only on the remote controller, replace the PCB (Part #701).

• If this error code appears on both the PCB (Part #701) and the remote controller, replace the

remote controller.

751: Miscommunication between water heater and built-in controller

• Check the power supply of the water heater.

• If this error code appears only on the green LED on the PCB (Part #701), check the voltage on the

buit-in controller terminal on the PCB. Refer to “Appendix E” in Section C.

• If this error code appears only on the buit-in controller, replace the PCB (Part #701).

• If this error code appears on both the PCB (Part #701) and the built-in controller,replace the

built-in controller.

991: Imperfect combustion*

• Refer to the “101” error code in this section.

*These error codes will be cleared when water flow stops.

C. Wiring diagram and check points on the water heater

W: WHITE

R: RED

O.H.C.F.

O.H.C.F.

Appendix A (For error code 111)

Check the following points during ignition stage.

# 1. Refer to check point “B” on the wiring diagram above.
Check the voltage between purple wires during the ignition process.
(Normal: 108 to 132 VAC)

Is the voltage within normal range?
Yes >> Replace the igniter assembly (Part #711).
No >> Go back to error code.

# 2. Refer to check points “C” and “H1” on the wiring diagram above.
Check the voltages below during the ignition process:
C: Between blue wire and light blue wire (#3).
(Normal: 93 to 120 VDC)
C: Between blue wire and orange wire (#9).
(Normal: 93 to 120 VDC)
H1: Check the voltage between white wire and red wire.
(Normal: 1 to 15 VDC)

Are these voltages within normal range?
Yes >> Replace the gas valve assembly (Part #102).
No >> Replace the PCB (Part #701).

# 3. Check the current through the orange flame rod wire (Part #709).

(Normal:morethan5μAwhenthereisaflame.)

Is the current normal when there is a flame?
Yes >> Replace the PCB (Part #701).
No >> Replace the flame rod (Part #107).

BK: BLACK
BL: BLUE

Igniter rod

IG

SV3

SV2

SV1

MV

BLBLBL

BL

BL
BLBLBL

Hi­limit

Switch

Gas
Propor-

onal

Valve

MAX buon

MIN buon

Increase buon

Decrease buon

Bank of DIP switches

P
P

R

O

G

LB

BL

C2
C1

BL

BL

W

R

Green LED

LB: LIGHT BLUE

Y: YELLOW

B

53

9

73

3

H1

E1
E2

987654321 10

OFF

PCB

C

L

W

A

G

I

H2

J

BK

Heater

BK

G

W

O

Y

BL

R

Y

G

O

Flame rod

R

W

BK

BK

R

BK

BK

F

Heater

Heater

Thermostat

BK

W

SW

Ground

FM

W

AFR rod

Flow
Sensor

Flow

Adjust-

ment

Valve

BK
BL

Temperature
remote controller

BK

Ground

G

Ground

thermistor

Outlet

thermistor

Inlet

R

Built-in controller

W

W

Surge

box

A2

120 VAC

Appendix B (For error code 611)

Y

Y

Refer to check point “G” in the diagram to the left and the following:

• Check the voltage between red wire and blue wire.

Y

B1

Y
Y

BK

(Normal: 132 to 192 VDC)

• Check the voltage between yellow wire and blue wire.
(Normal: 13 to 17 VDC)

• Check the voltage between orange wire and blue wire.
(Normal: 2.0 to 6.5 VDC)

W

BK

Are all of the voltages within normal range?
Yes >> Replace the fan motor (Part #103).
No >> Replace the PCB (Part #701).

A1

Appendix C (For error code 510 and 551)

Refer to check point “C” in the diagram to the left and the following.
Check the voltage on the each valve on the gas valve assembly.

• Between blue wire and light blue wire (#3) (Normal: 93 to 120 VDC).

• Between blue wire and green wire (#73) (Normal: 93 to 120 VDC).

• Between blue wire and orange wire (#9) (Normal: 93 to 120 VDC).

• Between blue wire and red wire (#53) (Normal: 93 to 120 VDC).

Are all of the check points normal?
Yes >> Replace the gas valve assembly (Part #102).
No >> Replace the PCB (Part #701).

Appendix D (For error code 311, 321)

• Outlet thermistor (Find the connector with No.113 stamped on it.)

Check point “E1” on the wiring diagram.

• Inlet thermistor (Find the connector with No.42 stamped on it.)

Check point “E2”on the wiring diagram.

Check the resistance between black wire and black wire.

Temperature

°F 50 59 68 77 86 95

°C 10 15 20 25 30 35

Resistance kΩ 15.4 12.6 10.3 8.5 7.0 5.9

Are all of the check points normal?
Yes >> Replace the PCB (Part #701).
No >> Replace the thermistor (Part #407, 408).

Appendix E (For error code 741 and 751)

Error code 741: Refer to check point “F” on the wiring diagram above.

Error code 751 : Refer to check point “L” on the wiring diagram above.
Check the voltage on the remote controller and/or built-in controller
on the PCB. • Between black wire and white wire. (Normal: 11 to 25 VDC)

Is this check point normal?
Yes >> Replace the remote controller and/or built-in controller.
No >> Replace the PCB (Part #701).

The tech should power the heater off and then on to reset the
error code.

D. DIP switch settings on the computer board of the water heater

Locate the bank of DIP switches at the bottom left of the computer board of the unit. Change the DIP switch settings when the
power supply is turned off. The dark squares indicate the correct DIP switch positions. DEFAULT is the factory setting.

High Altitude Function

Gas type

Natural

(DEFAULT)

Propane

Vent length

0 to 20 ft

(0 to 6.1 m)

21 to 40 ft
(DEFAULT)

(6.2 to 12.2 m)

41 to 60 ft

(12.3 to 18.3 m)

Two pipe direct

vent installation

ON

ON

ON

2,001 to 3,000 ft

(611 to 914 m)

3,001 to 5,000 ft
(915 to 1,524 m)

5,001 to 7,500 ft

(1,525 to 2,286 m)

7,501 to 10,100 ft

(2,287 to 3,078 m)

Indoor model

0 to 2,000 ft
(0 to 610 m)

DEFAULT

Vent Length and Installation

Vent length

0 to 60 ft

(0 to 18.3 m)

Vent length

0 to 55 ft

(12.3 to 16.8 m)

Single pipe with

room air intake

ON

100187154

ON

2,001 to 4,000 ft
(611 to 1,219 m)

4,001 to 6,000 ft

(1,220 to 1,829 m)

Vent kit

Outdoor model

0 to 2,000 ft
(0 to 610 m)

DEFAULT

ON

Outdoor

installation

ON

DIP switches

Temperature set

120 °F (50 °C)

(DEFAULT)

140 °F (60 °C)

E. Components diagram / Parts list

Case assembly

050

002

050

Indoor model

704

068

052

004

052

007

008

710

704

Surge box

053

062

703

715

050

002

003

052

001

007

008

050

Outdoor model

120

705

Burner assembly

056

151

113

055

107

052

706

108

106

053

Burner
assembly

105

111

053

112

150

117

116

052

701

062

053

716

121

062

709

102

Manifold
assembly

062

062

711

055

705

109

061

110

711

067

714

101

119

708

704

052

152

066

053

053

005

066

003

006

001

118

060

053

052

114

057

154

453

057

Item

110 U

#

310 U

001

002 N/A

003
004
005
006
007
008

050
051
052
053

054
055
056
057

058
059
060
061
062

064
065
066
067
068

115

122

414

122

N/A
N/A

N/A
N/A

N/A
100074668
100074603

N/A
100074201

100074210
100074509
100074211
100074245

100074510
100074248
100074247
100074511

100074512
100074272
100074514
100074244
100076450

N/A

N/A

N/A
100074385

N/A

053

104

Indoor model

153

104

054

Outdoor model

Part #

AT-KJr3U/K5U

-IN/OS

EW00D

401

103

054

401

103

Description

EK596
EK597

EK598
EK599

EK455
EK600
EK190
EKK4D
EK601

EM484
EW000

EW001
EW002
EW003

EW004
EW005
EW006
EW008

EW009
EW00A
EW00B

EW00E

EW016
EW018
EW02A

EKK31
EX014

Case assembly Indoor model

Front cover Indoor model

Bracket
Intake air port assembly
Junction box
Power supply cord assembly
Back guard panel
Overheat-cut-off fuse for combustion chamber

Truss screw M4×12 (W/Washer) SUS410
Truss screw M4×10 (W/Washer) SUS410
Truss screw M4×10 (Coated) SUS3
Truss screw M4x10 SUS

Hex head screw M4×12 (W/Washer) SUS3
Hex head screw M4x8 FEZN
Pan screw M4x10 FEZN
Pan Screw M3x10 SUS

Tapping screw M4x6 SUS3 Truss head
Tapping screw M3x6 SUS3 Pan head
Screw M3x6 SUS3 Binding head
Pan screw M4x8 MFZN
Tapping screw M4x14 SUS410 Truss head

Screw M3x6 BSNI Binding head
Pan screw M4x20 SUS410
Truss screw M4x8 SUS3
Tap tight screw M4x12 FEZN
Truss screw M4x10 MFZN3

Outdoor model

Built-in

temperature controller

(Indoor only)

065

Item

101
102

103 100074606

104 100074466

105
106
107
108
109
110

111
112
113

114
115
116
117

118
119

#

110 U
310 U

100224092
100224093

100074228

N/A

100076535
100224097

100224098

100224099
100224100
100076319

100270556
100224102
100224103

100074227
100074528
100074235
100074234

100224105
100224106

Outdoor model

721

Part #

AT-KJr3U/K5U

-IN/OS

EK554
EK555

EK109
EKK25

EM381

EK140
EKN58

EK559
EK560
EK561
EK562
EK462

EK602
EK564
EK565

EKK2D
EX019
EKK1E
EKK2Z

EK567
EK568

Water way assembly

454

C

722

409

052

Water outlet secon

Description

Burner assembly
Manifold with gas valve assembly NA

Fan motor for Indoor model
Fan motor for Outdoor model

Fan motor plate for Indoor model
Fan motor plate for Outdoor model

Burner window
Rod holder gasket
Flame rod with AFR function
Igniter rod
Rod holder
Rod cap

Burner damper
Manifold gasket A
Manifold gasket B

Pressure port
Combustion chamber tube
Gas inlet
Gas inlet ring

Burner gasket
Burner holder gasket

451

451

408

455

414

414

450

401

462

450

401

458

C

058

415

410

708

408

407

463

413

450

452

452

412

059

414

453

D

707

052

460

456

D

458

052

457

405

Water inlet secon

454

711

712

407406

701

To Water

inlet secon

To Water

outlet secon

Computer board assembly

714

066

064

402

404

103

709

402

402

461

052

705

721

415

058

Item

110 U

#

310 U

120

100074360
121
122

130
131

150
151
152
153

154
401 100270557

402
404
405
406

407 100074398 EKK4J Inlet thermistor for 110U, 310U
408 100074680 EK207 Outlet thermistor for 110U, 310U

409
410

412 100074412 EM212 Hi-Limit switch for 110U, 310U

413
414
415
416
417

450
451
452
453

454
455
456
457

458
460
461

462
463

701 100270582

703
704

705
706

707
708

709
710
711

712
714
715
716

721
722

N/A

100074369

100270585

100281157

N/A
100074242
100074390
100074400

100074403

100270558

100074624
100074377
100074381
100074382

100074627
100074264

100074252
100074682
100074629
100270581
100224113

N/A
100074310

N/A

N/A

100076303
100076305
100076306
100076307

100076308
100074290
100074410

100074389
100074250

100270583
100076100

100074601
100074323

N/A

N/A

100074649

N/A

N/A

N/A
100074640

100074458
100074642
100074655

N/A
100074660

N/A

AT-KJr3U/

K5U

-IN/OS

EK436
EK603

EKJ59

EK604
EK592

EK570
EK042
EKK3G
EKK53

EKK56
EK605

EK606

EK129
EKK1U
EKK2B
EKK2C

EK104
EK239

EX02A
EK209
EK105
EK609
EK577

EK616
EK031
EK476
EK610

EZM04
EZM06
EZM14
EZM15

EZM16
EKK24

EM192

EKK39
EKN50

EK611
EK612

EK280
EK146
EKK3C

EK614
EK590

EK189
EK585

EK586

EW022

EK153

EM329

EK112
EK184
EK615

EK173
EK588

Description

Surge box plate
PCB fixing plate
Thermostat

LP Conversion kit
Manifold gasket

O-ring P18 NBR (Manifold)
O-ring P20 NBR (Black)
Silicon ring for Outdoor model
Rain protection plate in Exhaust chamber
for Outdoor model
Exhaust port for Outdoor model

Heat exchanger assembly for Indoor

for Outdoor

Flow adjustment valve / Flow sensor
Water inlet
Inlet drain plug
Inlet water filter

Water outlet
Outlet drain plug

Overheat-cut-off fuse for heat exchanger
Pipe heater
Inlet heater
Pipe inlet
Joint outlet

Fuse fixing plate 40
Heater fixing plate 16
Fuse fixing plate 18
Pipe heater fixing plate

O-ring P4 FKM
O-ring P6 FKM
O-ring P14 FKM
O-ring P15 FKM

O-ring P16 FKM
Fastener “14-22”
Fastener “16A”

Fastener “16-25A”
Silicon ring for Indoor model

Computer board for 110U
Computer board for 310U

Surge box
120 VAC wire for Indoor model
for Outdoor model

Switch wire
120 VAC Power ON-OFF switch

Remote controller wire for 110 U, 310 U
Gas valve wire

Flame rod wire
Cable strap
Igniter assembly

Computer board cover
Proportional gas valve wire
Rubber grommet for Indoor model
Surge box cover

Temperature controller
Controller fixing plate

LP Conversion Kit

130

131

Part #