Navien NP Condensing Tankless Gas Water Heater - Service Manual

5.18. 34Error
Error occurrence conditions and check items.
Error
Description
34E
Water
Adjutment
valve error
If the water adjustment valve does not work properly due to a defective feedback
sensor, water adjustment valve or PCB board, the system displays 34E (cleared
automatically/manually), and switches into the Safety-Shutdown mode.
Water adjustment valve close error – The system commands opening of the water
adjustment valve, but the valve remains closed. [Check the feedback sensor.]
(Cleared manually)
If the Water adjustment valve sensor open/short-circuit is detected, the system
displays an error message. If flow is sensed, the system clears the error
automatically, provides the hot water. If open/short-circuit is detected after hot
water is used, the system displays the error message.
Check items
If the 34 error occurs, connect the good Water adjustment valve to the PCB.
valve must be kept open when the water heater does not work.
If the PCB is defective, the motor keeps operating and the valve repeats open/close.
1. Defective water adjustment valve.
2. Defective PCB.
Water Adjust Valve Feed Back
output voltage normal?
No
Replace Water Adjust Valve
Or Replace PCB
Check the voltage between black and white wire of
CN 22: 0.5 - 3.0V
©Navien America Inc. 2010
104
NR/NP series service Manual
Version 2.0