Furnace ignites but produces yellow, lazy flames instead of sharp blue flames.
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.
Possible Causes
How to Fix / Troubleshooting
Safety: Yellow flames can indicate incomplete combustion and carbon monoxide production. Turn off the furnace and ventilate the area. Install or check CO detectors.
Steps (limited homeowner actions):
- Check combustion air: Ensure combustion air openings or intake pipes are not blocked.
- Visual burner check: With power off, inspect burners for rust and debris. Do not attempt to adjust gas orifices.
Recommendation: A qualified technician must clean burners, verify gas pressure, and inspect the heat exchanger and venting.
Repair Difficulty
Required Part
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