Navien NFC-175, Service Manual

Page: 72 / 138

72 NFC Service Manual
Version 1.0
5.2.1 001Error
Error occurrence conditions and check items
Error Description
E001
Overheating of Heat
Exchanger
1. In order to prevent boiling in the heat exchanger, if the space heating water temperature is
higher than 216°F(102°C), E001 will be displayed on the front panel.
2. If the space heating water temperature decreases below than 216°F(102°C), E001 will be
automatically reset and the unit will repeat the combustion cycle.
3. If overheating occurs three (3) times consecutively, E001 will be displayed and must be
manually reset.
Check items
1. Check the circulation pump (external) operating status. Run Pump Test Mode.
2. Check if the strainer of the heating piping is clogged.
3. Check if the main heat exchanger is clogged.
4. Check the heating inlet / outlet valve and distribution piping for any obstructions.
5. Check the PCB DIP S / W capacity setting.
6. Check if the PCB is operating properly.
Verify thermistor readings at
the front panel. Is the supply
thermistor normal?
Verify checkpoints under Check Items list
Before measuring resistance of the thermistor,
detach the connector from the PCB.
Resistance between #7 and #8 of CNJ1 is from
0.437kΩ to 176kΩ at normal condition.
(see page 50-51 for Wiring Diagram)
Replace the supply thermistor
Yes
No