Danfoss Improper Combustion / Insufficient Air

The furnace ignites, but the flame appears yellow and sooty instead of blue and stable.

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

Restricted combustion air intake, dirty burner head, incorrect gas pressure, blocked heat exchanger passages.

How to Fix / Troubleshooting

Safety first: Sooty yellow flames indicate unsafe combustion and potential carbon monoxide production. Turn off the furnace and do not operate it until corrected.

Steps:

Check combustion air: Ensure the combustion air intake is not blocked and that the furnace room has adequate ventilation if using indoor air.
Inspect burner: With the power and gas off, remove and clean the burner head and ports. Do not alter the port sizes.
Do not adjust gas pressure yourself: Gas pressure and air settings must be checked with proper instruments by a qualified technician.
Schedule service: Have a professional perform a full combustion analysis and cleaning.

Repair Difficulty

Professional Required 5/5

Required Part

Danfoss Burner Assembly

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