Rinnai Error Code 34: Combustion Air Thermistor
Warning: Your Rinnai water heater is experiencing a combustion air thermistor issue, which has caused it to shut down. This is not an immediate safety risk, but it does require professional attention.
How to Fix Rinnai Code 34
- Step 1: Check if the water heater is receiving power. If not, ensure the circuit breaker is turned on.
- Step 2: Inspect the area around the water heater for any signs of damage or obstruction to the combustion air intake.
- Step 3: If the issue persists, contact a licensed HVAC technician to diagnose and repair the problem. Never attempt to open the water heater or tamper with its internal components.
How to Reset Rinnai Code 34
- 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.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Rinnai Error Code 34 Mean?
The Rinnai 34 error code indicates a problem with the combustion air thermistor, a safety component that monitors the temperature of the incoming air. When this sensor malfunctions, your water heater may shut down to prevent potential safety hazards. This issue is common in Rinnai water heaters and can be caused by a faulty sensor, improper installation, or damage from environmental factors.
Common Causes
- Faulty combustion air thermistor
- Improper installation of the thermistor
- Damage to the thermistor from environmental factors
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Water heater is not producing hot water | Check the error code display on the control panel | Rinnai 34 error code |
| Error code is displayed | Inspect the combustion air thermistor for any signs of damage or discoloration | No visible damage or discoloration |
Applicable Rinnai Models
- CU(gas)
- HE(dual_fuel)
- HE++ Series(gas)
- I-SERIES(gas)
- NCB(gas)
- NPE(gas)
- RE(gas)
- REP(gas)
- RL(gas)
- RU(gas)
- RUCS(gas)
- RX(gas)
- RXP(gas)
- Rinnai NCB Series(gas)
- Rinnai NPE Series(gas)
- Rinnai R Series(gas)
- Rinnai RL Series(natural_gas)
- Rinnai RU Series(natural_gas)
- Rinnai RUR Series(gas)
- Rinnai VSP(gas)
- V(gas)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Combustion Air Thermistor | RIN-101464000 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Rinnai model families as 34.
| Code | Description | Severity |
|---|---|---|
| 02 | Stagnant Water Detection | Warning |
| 10 | Air Supply/Exhaust Blockage | Warning |
| 11 | No Ignition | Warning |
| 12 | Flame Failure | Warning |
| 14 | Thermal Fuse | Warning |
| 16 | Over-Temperature | Warning |
| 19 | Electrical Grounding | Warning |
| 25 | Condensate Overflow | Warning |
| 29 | Condensate Neutralizer | Warning |
| 31 | Inlet Thermistor Failure | Warning |