Service manual

– 16 –
10kHz – 100kHz
DC0.5µA or less
BL-Burner case
BL-Electrode
1
1
Normal Value
AC90V – 110V
DC80V – 100V
DC80V – 100V
DC0.3V – 15V
2
7
7
4
W-BK
W-BL
BK-BL
R-BL
5
6
5
2
2. Fan rotates normally, but no flame ignites on the burner:
Normal Value
10kHz – 100kHz
DC1
µ
A or more
See pg. 24
DC0.3 – 15V
GND
F-
rod
4
BL-Burner case
BL-Electrode
R-BL
1
1
2
3. A flame ignites on the burner, but it goes out immediately:
71
70
11
11
72
Error
Code
Possible Causes
Checkpoint
Error
Code
Possible Causes
Checkpoint
Measure the current from the flame rod
when there is no flame.
Check for a ground fault.
Igniter failure
Check the flame rod
Check the current from the flame rod
Check for a diconnected ground from the
circuit board
Check gas supply and manifold
pressures
Check gas proportioning valve
Check primary gas solenoid valve
Check gas solenoid valve 1
Check gas proportioning valve
Gas Solenoid Valve Drive Circuit
Abnormality
Ignition Failure
Flame Detecting Circuit abnormality
(initial flame fault detection)
Gas Supply Pressure or Manifold
Pressure Abnormality
Flame Rod Abnormality
(Flame detected when no flame present)
CN-78
CN-10
CN-1(W), 10(BK)
CN-38
CN-38
Connector No.
CN-78
Connector No.
Pin No. &
Code Color
Pin No. &
Code Color
Replace Igniter
Gas Solenoid Valve typical resistance: 1075
Ω
to 1440
Ω.
Gas Solenoid Valve typical resistance: 1235
Ω
to 1660
Ω
.
How to Fix Problem and Reset Unit
Visually confir
m that a flame ignites, check wiring connections to flame rod, and
check wir
ing connections to gas proportioning and gas solenoid valves.
Check f
or a bad contact or a bad connection between flame rod and
circuit board
,
check for a ground fault in the unit, especially the
circuit board
ground.
Check for damage or improper connection of the ground wire between the
circuit
board
and the metal case of the unit.
Current value changes depending on the load.
How to Fix Problem and Reset Unit
GND
F-
rod
Detection of
circuit board
abnormality.
Circuit board
Abnormality
Disconnect the electrical power, then reconnect electrical power to the water heater to
reset the system. If the
circuit board
abnormality is continuous, replace the
circuit
board
.
Disconnect the electrical power, then reconnect electrical power to the water heater to
reset the system. If the error code "71" is continuous, replace the
circuit board
.
If the "72" error code is displayed, check the signal from the flame rod (also make sure
that there is not a problem with the grounding of the appliance).
If the signal is normal, replace the
circuit board
. If it is abnormal, replace the flame rod.
Current value changes depending on the load.
Normal Value
2.5 L/min.
1 or less
Connector No.
CN-63
CN-1
CN-63
CN-63
CN-63
2
6
2
2
2
W-W
BK-W
W-W
W-W
W-W
4
3
4
1
3
<During Regular Operation>
1. Fan does not begin rotating when hot water is being demanded:
No
Error
20
29
31
32
33
Error
Code
Possible Causes Checkpoint
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Pin No. &
Code Color
How to Fix Problem and Reset Unit
to be replaced.
Compare to temperature characteristic list on pgs. 16.
If no.19 is [001] : Only Electrode No.1 is ON, [010] : Only Electrode No.2 is ON,
[011] : Both Electrodes are ON, check the following :
Check for Drain Trap blockage. Check for drain pipe blockage.
Check for proper connection of Drain Trap water level electrode.
Check for short circuit of Drain Trap water level electrode cord.
If normal value, replace the circuit board.
Both Electrodes
OFF [000]
Compare to temperature characteristic list on pgs. 16.
Check for open or short circuit or for an improper connection.
Check for open or short circuit or for an improper connection.
Check for open or short circuit or for an improper connection.
Compare to temperature characteristic list on pgs. 16.
Normal Value.
W
Check maintenance monitor no. 14
Check inlet water temperature
Check if high limit switch is triggered or
improperly connected.
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Check the resistance through the thermistor.
Check for open or short circuit,or improper connection.
Water Flow Sensor Abnormality
Inlet Water Temperature is too High
Water Inlet Thermistor Abnormality
Drain Trap Water Level Electrode
abnormality
Check maintenance monitor no. 19
Water Outlet Thermistor Abnormality
Heat Exchanger Thermistor Abnormality
High Limit Switch Triggered
.
How to Fix Problem and Reset Unit
If the flow monitor indicates higher than the minimum, the circuit board will need
Make Sure there is no flame left over in the burner. Check for short or open
circuit. Reset unit by turning power off and on. Replace high limit if code remains.
.
.
OK if K > 1.6 x 25/Flow Rate (L/min.) + inlet water temp (°C), where K = 58°C for 53°C
or lower temperature setting, K= Set Temp (
°
C) + 10°C for 53°C or more setting.
Also check thermistor temperature characteristics.
Ω
Check for damage to the gas solenoid valve
drive circuit on the
circuit board
.
Proportioning valve resistance: 55
Ω
– 75
Ω
.
Proportioning valve resistance: 55
Ω
– 75
Ω
.