F.17
Lochinvar Fan Speed / Combustion Blower Fault

Boiler displays F.17, may still operate but with limited modulation

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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

Failed combustion blower, blocked fan wheel, faulty fan speed sensor, wiring issue between fan and control

How to Fix / Troubleshooting

Safety first: Disconnect power before removing the blower or accessing internal components.

  • Listen for blower operation: On a call for heat, the blower should start smoothly. Grinding, squealing, or no operation indicates a problem.
  • Inspect blower wheel: Remove the blower assembly per the Lochinvar service manual. Check for debris, broken blades, or heavy dust buildup. Clean with a soft brush and vacuum.
  • Check wiring harness: Ensure the multi-pin connector between the blower and control board is fully seated and free of corrosion.
  • Reset and test: Reinstall the blower, restore power, and reset the boiler. If F.17 returns, the blower motor or speed feedback circuit may be defective.

Professional help: Replacement of the combustion blower should be done by a qualified technician using the correct Lochinvar OEM blower.

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Repair Difficulty

Hard 4/5

Required Part

Combustion Blower
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