Navien NHB-055 Service Manual page 110

Check method
Fault
Defective sensor
Possible Issues
110 NHB Service Manual
Possible Causes
Defective temperature Check if the temperature sensor is open and if the connector is connected
sensor connector properly.
Check the resistance of the temperature sensor. (Defective if it is 30kΩ or higher)
Replace the temperature sensor if the resistance value is abnormal.
●
Temperature sensor
(refer to page 67)
Check the temperature displayed on the front panel.
●
(refer to page 38)
Defective PCB If the issues continue despite checking the items above, replace the PCB.
<Heat exchanger input temperature sensor / connector>
Check if the hot water temperature sensor is open (Error type : MΩ Open)
Check method
Version 1.0