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?
Содержание NPE-180A
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Страница 57: ...Version 2 21 56 NPE Service Manual 4 10 Electrical Diagnostic Points ...
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