Furnace produces unusual odors when running, such as burning dust or a metallic smell.

Safety: If you smell burning plastic, electrical, or a strong chemical odor, shut off the furnace and investigate. Install and check carbon monoxide detectors.

Steps to check:

• Initial seasonal smell: A light burning-dust smell at first startup of the season is common and should dissipate within an hour.
• Inspect registers and ducts: Look for toys, plastic, or debris near supply registers that could be heating up.
• Check around furnace: Ensure no paint cans, solvents, or chemicals are stored near the Heil furnace return air or combustion air inlets.

When to call a pro: Persistent or strong odors require a technician to inspect the heat exchanger, blower, and electrical components for overheating or contamination.