Napoleon
Rapid Cycling Due to Thermostat or Flame Sensing Issues
Furnace cycles on and off rapidly (every 1–5 minutes) without reaching temperature
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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
Oversensitive thermostat, Poor thermostat placement, Weak flame signal causing intermittent shutdown, Loose flame sensor connection
How to Fix / Troubleshooting
Safety first: Turn off power before working on the flame sensor or wiring.
- Thermostat location: Ensure the thermostat is not near supply registers, exterior doors, or heat sources. If it is, consider relocating.
- Clean flame sensor: Remove and clean the flame sensor rod with fine abrasive pad to ensure a strong flame signal.
- Check sensor wiring: Inspect the flame sensor wire from the sensor to the control board for damage or loose connections.
- Thermostat settings: For programmable thermostats, adjust cycle rate or differential settings per the manual to reduce rapid cycling.
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Repair Difficulty
Medium
3/5
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