72
Ruud
Flame Sensing Circuit Error
Ruud tankless water heater displays error code 72; unit may not detect flame correctly.
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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
Dirty or damaged flame rod, Loose flame rod wiring, Faulty flame sensing circuit on control board, Poor burner ground
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Allow the unit to cool.
- Step 1 – Clean flame rod: Remove the front cover. Locate and remove the flame rod. Gently clean it with fine emery cloth to remove oxidation. Do not bend the rod.
- Step 2 – Check wiring and ground: Inspect the flame rod wire and connector. Ensure the burner and chassis ground connections are tight and free of corrosion.
- Step 3 – Replace flame rod: If the rod is cracked, heavily corroded, or damaged, install a new OEM Ruud flame rod.
If error 72 persists after these steps, the control board flame sensing circuit may need replacement by a technician.
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Repair Difficulty
Medium
3/5
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