Service manual

– 14 –
Error Codes and Checkpoints
Description
Ignition Failure
(Initial Flame Fault
detection)
Flame Rod Does Not
Detect Flame (Secondary
Flame Fault Detection)
Overheat Cutoff Fuse
(Thermal Fuse) Triggered
Abnormally High Output
Temperature
High Limit Switch
Tr iggered
Water Inlet Thermistor
Abnormality
Water Outlet Thermistor
Abnormality
Heat Exchanger Thermistor
Abnormality
Multi-System CCP Valve
Abnormality
Fan Motor Abnormality
Main flow Control
Valve Abnormality
Bypass flow Control
Valve Abnormality
Gas Solenoid Valve Drive
Circuit Abnormality
Multi-System Controller
Board Error
Improper Circuit Board
Setting (Dip Switch etc.)
Remote Controller
Transmission Abnormality
Connection Error of Quick
Connect Cord
Combustion Abnormality
Combustion Abnormality
(Output Drop)
Combustion Abnormality
(Unit Shuts Off)
Flame Rod Circuit Abnormality
(Detection of Flame when
no flame is present)
Combustion Abnormality
(Joule Drop)
(Unit Continues Working)
Diagnosis Point (Trouble Point) Remarks
Display
(F) 10
(F)
11
(F)
12
(F)
14
(F)
16
(F)
20
(F)
31
(F)
32
(F)
33
(F)56
(F)
61
(F)
65
(F)
66
(F)
71
(F)
72
730
(F)
73
(F)
90
(F)
99
760
F
76
This error code is not mentioned in the flowchart.
This error code is not mentioned in the flowchart.
This model has two pieces of water level
electrodes. The front one is "No.2" and the
back one is "No.1".
Note 1)
Note 1)
Note 1)
Note 2)
During multi-system controller connection only.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to be
disconnected and then reconnected.
To reset this error code, the power needs to
be disconnected and then reconnected.
To reset this error code, the power needs to be
disconnected and then reconnected.
This code is not mentioned in the flowchart.
This code is not mentioned in the flowchart.
This error code is not mentioned in the flowchart.
To reset this error code, the power needs to be
disconnected and then reconnected.
To reset this error code, the power needs to be
disconnected and then reconnected.
To reset this error code, the power needs to be
disconnected and then reconnected.
Check for abnormal combustion.
Check flue for blockage or obstruction.
Check for accidental extinction of the flame. Check for
abnormal combustion, check gas solenoid valves, check
flame rod. Check ground, especially on circuit board.
Check for melting or damage to the overheat cutoff fuse.
Check for improper connection of overheat cutoff fuse.
Measure the resistance through the water outlet thermistor.
Check for gas proportioning valve trouble.
Check gas manifold pressure.
Check if high limit switch is triggered.
Check for improper connection of high limit switch.
Measure the resistance through the water inlet thermistor.
Check for an open or short circuit.
Check for improper connection of the water inlet thermistor.
Drain trap Water Level
Electrode Abnormality
(F)29
Check for Drain trap blockage.
Check for drain pipe blockage.
Check for proper connection of drain trap water level electrode.
Measure the resistance through the heat exchanger
thermistor. Check for an open or short circuit. Check for
improper connection of the heat exchanger thermistor.
Check for an obstruction in the CCP valve.
Check for improper connection of multi-system wiring.
Check the inlet filter for an obstruction.
Check that the main flow control valve is functioning.
Check for the failure of the water flow sensor.
Heat exchanger flow
abnormality
(F)59
Check for scale build-up in heat exchanger.
Check for abnormal combustion.
Check flue for blockage or obstruction.
Check hat flame ignites all across the burner.
Check that the fan is rotating. Check for improper connection
of the fan. Check the pulse frequency from the fan rotational
frequency sensor. Check voltage from circuit board.
Check that the main flow control valve is functioning.
Check for improper connection of the valve.
Multi-System Controller
Communication Error
76
Check connection from remote controller to circuit board.
Check remote controller and circuit board for damage.
Check connection from multi-system controller to the unit.
SCU failure. Check for the circuit board of each unit.
Check that the bypass flow control valve is functioning.
Check for improper connection of the valve.
Check for damage to the gas solenoid valve drive circuit on
the circuit board.
Measure the current from the flame rod when there is no
flame. Check for a ground fault.
Malfunction of system controller electrical component board.
Circuit Board Abnormality
Number of the unit
decrease
(F) 70
Circuit board failure.
Check for proper setting of maintenance writers on circuit
board. Check circuit board for damage, check wiring
connections to circuit board.
Check connection from remote controller to circuit board.
Check remote controller and circuit board for damage.
Check for proper connection of quick connect cord.
Check for the circuit board of each unit.
Visually check flame. Check flue for blockage.
Visually check flame. Check flue for blockage.
Check that flame ignites all across the burner.
Check for abnormal combustion.
Check flue for blockage or obstruction.
Measure the resistance through the water outlet thermistor.
Check for an open or short circuit.
Check for improper connection of the water outlet thermistor.
Check gas supply piping and pressure. Check for igniter
spark. Check gas solenoid valves. Check flame rod.
Check ground, paying special attention to the ground
connection to the circuit board.
*In a Quick Connect (2-unit) Multi-System, "F##" (except F76) indicates an error code from the secondary unit (unit without a remote).
F76 refers to the connection error of quick connect cord.
Note 1) System controller connection only.
Note 2) The ON/OFF condition of both water level electrodes can be checked using the maintenance monitors.
When maintenance monitor number 19 reads "000", the conditions of both electrodes are normal. When this monitor reads "011",
the conditions of both electrodes are abnormal.
When this monitor reads "001", the condition of the only electrode "No. 1" is abnormal.
When this monitor reads "010", the condition of the only electrode "No. 2" is abnormal.
63
Circulation Pump
Abnormality
Check for a damage of Circulation Pump. Check for improper
connection of the circulation pump. Check for improper
Circulation pipe. Check for pump control unit.
Checkpoints and Measures if a Breakdown Occurs