Code 72
Rinnai
Flame Sensing Circuit Fault
Unit displays Code 72; ignition may start but flame sensing is unreliable
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Damaged flame rod, Loose flame rod wiring, Poor ground connection, Faulty control board flame circuit
How to Fix / Troubleshooting
Safety first: Turn OFF gas and power. Allow the unit to cool before working near the burner.
Steps to check:
- Inspect flame rod: Remove and examine the flame rod for cracks, heavy deposits, or corrosion. Clean lightly with fine abrasive pad.
- Check wiring and ground: Ensure the flame rod wire is secure and the unit chassis is properly grounded.
- Reset and test: Restore power and gas, reset the unit, and observe operation.
When to call a professional: If Code 72 persists, the flame rod or control board may need replacement and combustion should be checked by a technician.
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Repair Difficulty
Hard
4/5
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