What Causes the Burning Smell When I Turn on My Furnace?

Normal Dust Burn-Off

When the furnace or heat pump is not actively heating, dust and dirt particles can settle inside the furnace and on internal components. When you turn on the furnace the dust burns off, causing a light burning smell that should dissipate relatively quickly. If it lingers beyond an hour or so, check the air filter and replace it if needed, or contact Choice Comfort Services to inspect the system.

Not-So-Normal Odors

While that initial dusty/burnt smell is common, there are some not-so-normal odors you should be aware of as well:

• Electrical, metallic, or plastic burning smell - Follow your nose to locate the source. If it is coming from your furnace it could be an overheated motor, worn bearing or a wiring issue – and it is time to call Choice Comfort Services. If it is coming from a specific register/vent, it could be a plastic toy or other foreign object in the duct. Again, it is best to call a qualified HVAC technician or duct specialist if you do not see an object in the duct.
• Musty/moldy/locker room smell - Your air filter could be overly dirty, or you may even have a little mold or bacterial buildup somewhere in your home. Check and replace the filter if needed. Another source could be organic growth on the cooling (evaporator) coil or in your ductwork. Both of those will require professional cleaning by an HVAC company or duct cleaning specialist.
• Rotten eggs/sulfur - Any time you smell rotten eggs or sulfur when gas appliances are in the home, it is time to leave the premises and call the gas company – immediately. Gas leaks are dangerous and should always be handled by trained professionals.