Navien NPE-240A Service Manual

Troubleshooting 103
Check connector motor resistance
(CON8)
(see page 52 for Wiring Diagram)
Panel Test operation mode
(WAV operation)
Reset the unit
Yes
Is the operation normal?
NO
Check method
Fault Possible Causes Check method
Remote controller /
PCB error
Malfunction of water
adjustment valve
Defective water
adjustment valve
If an error occurs in the cascade system, disconnect the cascade cable and check the
system in the following procedure:
1. Check the operation of the water adjustment valve using the Component Test
mode (refer to page 47).
2. If the PCB is defective, the motor keeps operating as the water adjustment valve is
OPEN or CLOSED, or the valve repeats open/close.
3. Replace the water adjustment valve for other symptoms.
4. As a temporary measure, you can disassemble the water adjustment valve, open it
manually, and separate the power cable of the water adjustment valve.
Water heater works but
error occurs
Defective water
adjustment valve
sensor
1. Open or short-circuit of the flow control valve sensor.
2. Check the connector assembly and wiring state of the water adjustment valve
feedback sensor.
3. Check the operation of the water adjustment valve using the Component Test
mode (refer to page 47).

Navien NPE-240A Specifications

General

Type	Tankless
Fuel Type	Natural Gas or Propane
Energy Factor	0.97
Energy Efficiency	97%
Voltage	120V
Ignition Type	Electronic
Maximum Input	199, 900 BTU/h
Water Connection Size	3/4"
Gas Connection Size	3/4"
Warranty	15-year on heat exchangers, 5-year on parts, 1-year on labor
Dimensions	17.3" W x 13.2" D x 27.4" H