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T-H2-DV/T-H2-OS Service Manual
Ver. 1.01
53
CONFIDENTIAL
Error Code
Malfunction description
Cancellation method
711
1.
Hi-limit switch trip /
Overheat cutoff fuse compromised
NOTE: When these components are compromised,
the “711” error code may appear instead of
the “111” or “121” error codes.
Turn off the power supply
2.
Driving circuit fault for gas solenoid valve (VG
0
)
Diagnosis
Checkpoint
1(A) Hi-limit switch trips (Refer to section 10-14)
Visual insplection: connection/breakage of wires.
Normal: Less than 1
Ω
between blue & blue
C1
1(B) Overheat cutoff fuse compromised (Refer to section 10-16)
Visual inspection: connection/breakage of wires.
Normal: Less than 1
Ω
between blue & blue
C2
2 PCB and/or gas valve fault (Refer to section 10-5 & 10-18)
Visual inspection PCB: connection/breakage of wires and/or burn
makes on the computer board.
C
Error Code
Malfunction description
Cancellation method
721
False flame detection
Turn off the power or water supply
Diagnosis
Checkpoint
1 False flame detection (5 sec.)
Flame rod (Insulated resistance) fault
I
Error Code
Malfunction description
Cancellation method
741
Miscommunication between water heater and
temperature remote controller
Restoring proper cable connections
between the water heater and the
Remote controller (TM-RE30). When the
computer detects proper connections
between the water heater and the
remote controller, "741" error code will
cease to display.
Diagnosis
Checkpoint
1 Temperature remote controller (TM-RE30) or PCB fault
2 Check for signs of power surges.