Code 14
Rinnai Thermal Fuse / Overheat Cutoff Activation

Unit shuts down with Code 14; outer case may feel warm and fan may run after shutdown

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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

Scale buildup in heat exchanger restricting flow, Blocked air filter or vent, Faulty thermistor or thermal fuse, Low water flow causing localized overheating

How to Fix / Troubleshooting

Safety first: Turn OFF gas and power. Allow the unit to cool completely before touching internal components.

Steps to check:

  • Clean intake air filter: Remove the front cover and locate the air filter. Wash with mild soap and water, dry thoroughly, and reinstall.
  • Check for scale buildup: If the unit has not been descaled in the last 1–2 years (or sooner in hard water areas), mineral buildup may be causing overheating. A professional descaling of the heat exchanger is recommended.
  • Verify water flow: Ensure inlet water shutoff valves are fully open and any inlet screen filter is clean.
  • Reset the unit: After cooling and cleaning, restore power and gas and reset. If Code 14 returns quickly, stop using the unit.

When to call a professional: A technician should test the thermistors, thermal fuse, and inspect the heat exchanger for scale or damage. Replacement of the thermal fuse or descaling may be required.

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Repair Difficulty

Hard 4/5

Required Part

Thermal Fuse
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