Alpha Contaminated Combustion Air / Overheated Components

Furnace causes a strong chemical or metallic odor when running.

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

Furnace drawing in fumes from nearby chemicals (paints, solvents), Overheating blower motor windings, Melting plastic components near heat exchanger, Cracked heat exchanger leaking combustion gases into air stream

How to Fix / Troubleshooting

Safety: Chemical odors and metallic smells can indicate serious issues. Turn off the furnace and ventilate the area. Do not ignore persistent unusual odors.

Remove chemicals: Ensure no paints, solvents, or cleaners are stored near the furnace or combustion air intake.
Inspect for melting: With power off, look for discolored plastic parts, wiring, or insulation inside the furnace cabinet.
Do not operate if odor persists: A cracked heat exchanger is a serious safety hazard and must be inspected by a licensed technician.

Repair Difficulty

Professional Required 5/5

Required Part

Alpha Primary Heat Exchanger

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