407Error - Navien NPE-180A Service Manual

Check method
Fault Possible Causes
Abnormal flow of
110E
intake air supply /
Exhaust blockage
Condensate drain error Condensate drain error
Deformed or clogged
Defective air supply/
exhaust flue
Exhaust gas flows in
through the supply

5.1.11 407Error

Error conditions and Check Items
Error
E407
Hot water outlet If an error (open: 14°F (-10°C) or lower) in the Hot water outlet temperature sensor is detected, the system
Temperature sensor displays the 407E error on the front panel. If this occurs, the water heater initiates shutdown.
open / short
1. Check if the Hot water outlet temperature sensor connector is wet due to any reason, including leakage.
2. Check the Resistance of the Hot water outlet temperature sensor.
Check items
3. Replace the defected Hot water outlet temperature sensor.
4. Replace the controller.
1. If 110E occurs intermittently during ignition or combustion, compare the standard
RPM with the current RPM at Min / Max combustion (dip switch 1-1&1-2). If the
current RPM is higher than normal, check the following:
Air supply / exhaust vent for any blockages.
●
Blocked condensate drain
●
exhaust
If the air pressure sensor hose is broken or clogged.
●
2. Replace the old PCB with the latest version.
Exhaust air is blocked due to condensate drain error.
Check if the condensate hose or the siphon is frozen.
●
Check if the condensate hose is kinked.
●
Remove bottom of trap and verify it is not blocked.
●
1. Check the exterior of the flue for damage and obstructions.
flue
2. Check if rainwater is collected due to vertical installation of the air intake pipe.
If the exhaust gas enters into the air supply pipe, abnormal combustion may cause
E110.
pipe
Check the installation of the flue.
●
Check method
Description
Troubleshooting 99