Service manual

– 17 –
Normal Value
DC7V – 48V
DC10V – 14V
150Hz – 400Hz
(4 pulse/rev.)
2
2
2
BR-BL
R-BL
Y-BL
4
1
3
5. Fan does not begin rotating, or the fan rotation is abnormal when hot water is being demanded:
Normal Value
See pg. 24
DC1 – 16V
DC1 – 16V
DC1 – 16V
DC1 – 16V
DC1V or less
DC1 – 16V
DC1 – 16V
DC1 – 16V
DC1 – 16V
DC1V or less
DC1 – 4.5V
DC0.3 – 15V
26
27
28
30
29
15
16
17
18
29
2
4
BL-O
BL-G
BL-V
BL-BK
Y-BL
BL-O
BL-G
BL-V
BL-BK
Y-BL
W-W
R-BL
25
25
25
25
24
25
25
25
25
20
1
2
6. Temperature control problem:
61
65
66
16
Check that the fan is rotating and check
the pulse frequency from the fan rotational
frequency sensor.
Check for improper connection of the fan.
Check voltage from
circuit board
.
Check gas supply and manifold
pressures.
Check main flow control valve.
is functioning. Check for improper
connection of the valve.
Check gas proportioning valve.
Check the resistance of the water outlet
thermistor.
Fan Motor abnormality
Gas supply pressure or manifold
pressure abnormality
Main Flow Control Valve Abnormality
Bypass Flow Control Valve Abnormality
Abnormally High Output
(temperature is too hot)
Connector No.
CN-27
Connector No.
CN-38
CN-38
CN-63
CN-38
Pin No. &
Code Color
Pin No. &
Code Color
During Operation.
During Operation.
During Operation.
During Operation.
When valve is fully open.
If the heat exchanger thermistor temp. is 92
°
C and over for 0.3 second with the all
set temp.
If the outlet thermistor temp. is 90
°
C and over for 0.3 second with the all set temp..
If the outlet thermistor temp. is (set temp. + 10
°
C) and over for 25 seconds with the
set temp. more than 50
°
C.
If the outlet thermistor temp. is 60
°
C and over for 25 seconds with the set temp.
50
°
C and less. The unit will shut off and a 16 error code will flash.
When valve is fully open.
Check for short or open circuit or improper connection of wiring to valve.
During Operation.
During Operation.
During Operation.
During Operation.
No
Indication
Error
Code
Possible Causes
Checkpoint
Error
Code
Possible Causes
Checkpoint
How to Fix Problem and Reset Unit
How to Fix Problem and Reset Unit
Confirm the measured fan speed by Maintenance Monitor (No.10).
If the fan motor does not rotate, but voltage is normal, then the fan motor should
be replaced. If the voltage is abnormal, replace the
circuit board
.
If the fan motor is rotating and if the voltage is normal, but there is a "61" error
code, then the fan motor should be replaced.
Check for improper connection of the valve.
Check that the bypass flow control valve
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
4. Flame goes out while hot water is being supplied:
12
Error
Code
Possible Causes
Checkpoint
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
Flame Rod Triggered
(Doesn't sense flame during operation)
Gas Supply Pressure or Manifold
Pressure Abnormality
CN-78
CN-38
Connector No.
Pin No. &
Code Color
Visually confirm that a flame ignites, check wiring connections to the flame rod,
and check wiring connections to gas propor tioning and gas solenoid valves.
Check for a bad contact or a bad connection between the flame rod and
circuit board
.
Check for a ground fault in the unit, especially the
circuit board
ground.
Check that the input is proper for the load.
Current value changes depending on the load.
Proportioning valve resistance: 55
Ω
- 75
Ω
.
How to Fix Problem and Reset Unit
Check for damage or improper connection of the ground wire between the
circuit
board
and the metal case of the unit.
<During Regular Operation>
Water Inlet
/
Water
Outlet / Heat Exchanger Thermistor Temperature Characteristics
Ω)
Temperature (
˚C
)
Resistance (k
7.010.315.523.7
0 2010 30
1.41.9
2.53.54.9
5040 60
70
80