51
Rinnai
Combustion Fan Motor Fault
Boiler shows error 51; fan may not start or may run erratically.
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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
Seized or obstructed fan, Faulty fan motor, Loose fan wiring connector, Control board fan drive failure
How to Fix / Troubleshooting
Safety first: Isolate power and gas. The fan area may be hot and sharp edges may be present.
- Access fan assembly: Remove the front cover and locate the combustion fan near the top of the boiler.
- Check for obstructions: Inspect the fan wheel for debris, insulation, or wiring contacting the blades. Remove any obstructions carefully.
- Spin test: With power off, gently rotate the fan wheel by hand. It should spin freely without grinding or binding.
- Verify wiring: Ensure the fan motor connector is fully seated and wires are not damaged.
- Reset and observe: Restore power and reset the boiler. If the fan fails to start or error 51 returns, the fan motor or control board will likely need professional replacement.
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Repair Difficulty
Hard
4/5
Required Part
Combustion Fan Motor
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