Navien NPE-240A Service Manual

Troubleshooting 105
5.1.15 438Error ("A" models only)
Error occurrence conditions and check items
Error Description
E438
Pump error
Connect the power, start the pump, and check if the system senses water flow.
If flow is not sensed after the pump has started, the system displays 438E (cleared automatically) on the front
panel.
Check items
1. Defective flow sensor.
2. Defective pump.
* Check water filter for debris.
* Check for locked air in the pump.
3. Defective PCB.
* Check the operation of the pump and flow sensor using the Component Test mode (refer to page 47).
Check water flow sensor Check the PUMP resistance
Panel Test operation mode
(PUMP operation)
Supply cold water to the water
heater.
Reset the unit
Check the voltage #1 and #3 of CON2: 97 - 138VAC
(see page 52 for Wiring Diagram)
NO
NO NO
Yes
Yes Yes
Is there cold water
supply inside water
heater?
Is the circulation pump
operating normally?
Is the pump operating
at normal voltage?

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