Ruud Error Code 31: Inlet Water Filter
Warning: Your Ruud tankless water heater has detected a possible blockage in the inlet water filter, which can cause the unit to shut down. This requires troubleshooting to restore hot water.
How to Fix Ruud Code 31
- Step 1: Locate the inlet water filter on your Ruud tankless water heater. It's usually near the cold water inlet pipe.
- Step 2: Close the cold water shut-off valve to the unit.
- Step 3: Carefully remove the filter housing and inspect the filter. If it's visibly dirty, rinse it thoroughly under running water. For heavy buildup, soak it in a vinegar solution.
- Step 4: Reinstall the cleaned filter and filter housing, ensuring a tight seal. Open the cold water shut-off valve slowly.
- Step 5: If the error code persists after cleaning the filter, or if you're uncomfortable performing these steps, contact a qualified HVAC technician for assistance.
How to Reset Ruud Code 31
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
What does 31 mean?
The '31' error code on your Ruud tankless water heater indicates a potential issue with the inlet water filter. This filter is designed to prevent sediment and debris from entering the unit and damaging its internal components, like the heat exchanger. When the filter becomes clogged, it restricts water flow, causing the unit to operate inefficiently or shut down completely. This can lead to inconsistent hot water temperatures or a complete loss of hot water. Ignoring this error can lead to scaling and mineral buildup inside the heat exchanger, which is a much more costly repair.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Inlet Water Filter | — | — |
| Inlet Water Filter Housing | — | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| 11 | No Ignition | Critical |
| 12 | Flame Failure | Critical |
| 13 | Improper Combustion | Critical |
| 14 | Overheat / Thermal Fuse | Critical |
| 15 | Inlet Temp Sensor Fault | Warning |
| 16 | Outlet Temp Sensor Fault | Warning |
| 21 | Air Supply / Operational Switch | Warning |
| 24 | Flow Sensor Malfunction | Warning |
| 29 | Condensate Neutralizer Issue | Warning |
| 33 | Fan Motor Fault | Warning |