434Error - Navien NFC-175 Service Manual

5.2.23 434Error

Error Condition and Check Items
Error
E434
Check Items
108 NFC Service Manual
Abnormal operation: Water adjust valve
1. Check for water adjust valve harness disconnection.
Check for harness disconnection in case no feedback signal.
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2. Change water adjust valve
If the problem persists after completing (1), close external water intake supply valve and
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purge water pipes of residual water. Change water adjust valve.
3. Change PCB
If the problem persists after completing all the actions above, change the PCB.
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water adjust
valve connector
Description
Water adjust valve
Version 1.0