110 NPE Service Manual
5.1.17 441Error
Error occurrence conditions and check items
Before measuring resistance of the thermistor,
detach the connector from the PCB.
Check connector
( #3 and #4 of CON 7)
(see page 52 for Wiring Diagram)
Replace heat exchanger outlet
thermistor
Resistance between #3 and #4 of CON 7 is from
0.437k to 176k at normal condition.
NO
Is the heat exchanger
outlet thermistor
operating normally?
Yes
5.1.18 445Error
Error occurrence conditions and check items
Error Description
E445
Mixing valve error
If the mixing valve does not work properly due to a defective feedback sensor, mixing valve, or PCB board, the
system displays 445E (cleared automatically/manually).
●
Mixing valve error – The system commands opening of the mixing valve, but the valve remains closed. [Check
the feedback sensor.] (Cleared manually)
●
If a mixing valve sensor open or short-circuit is detected, the system displays an error message. If flow is
detected, the system clears the error automatically and provides hot water. If an open or short-circuit is
detected after hot water is used, the system displays the error message.
Check items
If the 445 error occurs, connect the mixing valve to the PCB. The valve must be kept open when the water heater
is not operating. If the PCB is defective, the motor keeps operating and the valve continually attempts to open or
close the valve.
1. Defective mixing valve
2. Defective PCB
3. Check the operation of the mixing valve using the Component Test mode (refer to page 47).
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