Flow Sensor (To Be Revised) - Navien NCB-24LSWE Service Manual

4.9.10 Flow Sensor (to be revised)

Item
Function
Fault
Symptoms
Error codes
Diagnostics
Version 1.0
To detect water flow in LPM (litres per minute) to provide a steady hot water temperature.
1. Unable to detect or measure water flow rate.
2. Damage to and/or leakage from the water flow sensor.
1. Ignition does not start.
2. Boiler operation stops when water leakage is detected.
E439
1. Visual inspection: Check wire connections are secure and inspect for wire damage.
2. Visual Inspection: Check for sensor damage and for scale forming on the sensor.
Description
NCB Service Manual 69