Ducane Combustion / Venting Hazard

Furnace runs but carbon monoxide detector alarms

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

Cracked heat exchanger on Ducane furnace, Blocked flue, Improper venting slope, Backdrafting from negative house pressure

How to Fix / Troubleshooting

Emergency safety warning: If a CO detector alarms, immediately turn off the furnace, evacuate the building, and call emergency services.

Step 1 – Shut down furnace: Turn off power and gas to the furnace.
Step 2 – Ventilate: Open windows and doors to allow fresh air in.
Step 3 – Do not restart: Do not operate the furnace again until it has been inspected and cleared by a qualified HVAC technician.
Step 4 – Professional inspection: A technician must inspect the heat exchanger, venting, and combustion and may need to replace the furnace if the heat exchanger is cracked.

Repair Difficulty

Professional Required 5/5

Required Part

Primary Heat Exchanger

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