Rinnai Error Code 63: Rinnai Code 63 - Excessive Temperature Rise
Warning: The water heater has shut down due to a rapid temperature increase. This prevents scalding and damage, but you'll have no hot water until it's fixed.
How to Fix Rinnai Code 63
- Step 1: Check that all hot water taps are fully closed. A dripping faucet can cause the unit to cycle and potentially trigger the error.
- Step 2: Try resetting the unit by turning off the power at the breaker for 30 seconds, then turn it back on. This may clear a temporary fault.
- Step 3: If the error persists after resetting, contact a qualified HVAC technician experienced with Rinnai tankless water heaters for professional diagnosis and repair.
How to Reset Rinnai Code 63
- 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 63 mean?
Rinnai error code 63 indicates an excessive temperature rise within the heat exchanger. The unit's sensors detected the water temperature increasing too quickly, triggering a safety shutdown. This usually means the burner is firing too intensely for the amount of water flowing through the unit. It's a protective measure to prevent scalding, damage to the unit, and potential steam explosions. The unit will lock out and display this error until the problem is resolved. This issue affects the burner assembly, water flow regulation, and temperature sensors within your Rinnai tankless water heater. Ignoring this error can lead to further component damage or even a dangerous situation.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Flow Sensor | 804000047 | — |
| Thermistor | 804000083 | — |
| Gas Valve | — | — |
Related Codes on Same Models
| 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 |