Navien Error Code E311: Abnormal water level
How to Fix Navien Code E311
- Step 1: Check the condensate drain line (usually a white PVC pipe) for any visible kinks, clogs, or obstructions. Clear any blockages you can safely reach.
- Step 2: Try power cycling the unit by turning it off at the breaker for a few minutes, then turning it back on. This may reset the sensor.
- Step 3: If the error persists after these steps, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Navien Code E311
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
What does E311 mean?
The E311 error code on your Navien tankless water heater indicates that the unit's internal sensors have detected an abnormal water level. This usually means either the water level is too high or too low within the tankless unit itself. This is a safety mechanism to prevent the unit from running dry (overheating the heat exchanger) or from overflowing and damaging internal components. When this happens, the unit will lock out and stop producing hot water until the issue is resolved. This error can be triggered by a variety of factors, most commonly related to water flow, sensor issues, or problems with the unit's drain system.
Because tankless units rely on precise water flow and level detection, it's important to address this issue promptly. Ignoring it could lead to further damage to the heat exchanger, pump, or other components. While some causes are simple to address, others require a qualified technician to diagnose and repair.
Affected Models
- NCB-H
- NFB-H
- NFC-H
- NHB-H
- NHW-A
- NPE-A2
- NCB
- NCB
- NCB
- NPE
- NPE
- NPE
- NHB
- NHB
- NCB
- NCB
- NPE
- NPE
- NCB
- NCB
- NPE
- NCB
- NPE
- NHB
- NCB
- NPE
- NPE
- NCB
- NCB
- NPE
- NPE
- NPE
- NPE
- NHB
- NHB
- NCB
- NCB
- NPE
- NPE
- NBP
- NPE
- NPE
- NPE
- NFC
- NFC
- NCB
- NPE
- NPE
- NPE
- NCB
- NPE
- NCB
- NPE
- NPE
- NCB
- NPE
- NHB
- NPE-S
- NPN
- NPN
- NCB
- NPE
- NCB
- NPE
- NHB
- NPB
- NFC
- NFC
- NHB
- NPF
- NPF
- NPE
- NHB
Source Documentation
| Manual | Page | Reason | Action |
|---|---|---|---|
| Navien NPF Installation & Operation Manual | 127 | Abnormal water level | This error occurs when the sensor on the furnace for water level detection does not operate properly. ● Turn off the furnace, turn it on again and check if the furnace operates properly. ● If the furnace is continuously inoperable, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Water Level Sensor | 30012345A | — |
| Condensate Pump | — | — |
| Flow Sensor | 30009876B | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |