Why Does My Furnace Smell Like It’s Burning?

Follow your nose: If you notice that fish smells rancid, an egg smells rotten, or a carton of milk smells sour, it means something is wrong. It also tells you that something is wrong if your furnace smells burning. Should you worry about what you smell? Here's a guide to what any burning smell coming from your furnace means and how dangerous it can be.

Burnt Toast Smell

When you first start your heater in the fall, this smell may be caused by the buildup of dust, dirt, and other burning residue. Dust can accumulate in the ducts, heat exchanger, burner and other parts and produce a strong odor.

It is normal for stationary radiators to give off this smell at the start of the heating season after several months of dirt building up. Just wait several hours for the aroma to disappear. You can speed up the process by opening a door or window to allow the smelly air to escape.

Electrical Odors

Burning smells that arise when you don't turn on your heater for the first time can be dangerous. This is usually caused by an overheated fan motor and the system then shuts down. If this safety system is compromised, cycling the engine on and off may cause it to stop running and become dangerously hot. The culprit can also be a frayed or broken, overheated or burned out wire.

Bannister Plumbing & Air’s experienced technicians are available 24/7 to handle furnace emergencies like these where time is of the essence.

Plastic or Rubber Odors

A smell of plastic or smoldering rubber may indicate that a toy, bottle cap, straw, or other plastic object is stuck in a box or pipe. They burn at very high temperatures and release fumes that can be dangerous if inhaled.

The problem can also be caused by faulty shielding on the plastic wires. This shield can eventually crack or wear out, fall into the heating area of your furnace and melt. Electrical wires can also overheat if too much current flows through them, melting or burning out the plastic casing and dangerously exposing the bare wire underneath. Your device may soon short circuit and produce sparks, creating a burning rubber smell.

Smoky Odors

If your furnace's chimney is clogged or obstructed, the furnace will overflow air ducts and send smoke smells directly into your home. Sometimes birds or rodents build their nests in chimneys. Dirt such as leaves and twigs can also clog it. Dirty channels or a dirty, clogged filter can also be the cause.

Another possibility is that you have closed too many heating vents in your home to reduce energy costs. However, if you close too much, hot air can build up in the heating system and cause a smoky smell as well as overheating and cracking in the radiator. As a rule of thumb, you should only close up to 20 percent of your vents.

Soot Smell

If your old heater produces smoke that smells like soot, this indicates a serious problem. Soot is created by partial combustion. This means that your heater is not burning the gas properly.

If your heater's heat exchanger is cracked, soot will enter your home's vents. This means your furnace will ignite and spray soot all over your home (also known as a puff explosion), releasing toxic fumes. Soot is also very flammable, so a large accumulation of it poses a fire hazard.

FAQs about Why Your Furnace Might Smell Like It's Burning:

Q: Why does my furnace smell like it's burning?

A: There are a few reasons why your furnace might smell like it's burning. The most common reasons are:

  • Dust buildup: Dust can collect on the internal furnace parts, such as the heat exchanger, burner, and blower motor. This dust can catch fire and produce a burning smell.
  • Gas leak: If there is a gas leak in your furnace, it can create a burning smell.
  • Overheated furnace components: If the furnace is overheating, it can cause the components to smoke or burn, producing a burning smell.
  • Electrical problems: Electrical problems, such as a short circuit or a faulty wire, can also cause a burning smell.

Q: What should I do if my furnace smells like it's burning?

A: If your furnace smells like it's burning, the first thing you should do is turn it off. Then, you should call a qualified HVAC technician to diagnose the problem and make the necessary repairs.

Q: Can I use my furnace if it smells like it's burning?

A: No, you should not use your furnace if it smells like it's burning. Using a furnace with a burning smell can be dangerous and can lead to a fire.

Q: How can I prevent my furnace from smelling like it's burning?

A: There are a few things you can do to prevent your furnace from smelling like it's burning, including:

  • Have your furnace inspected and cleaned regularly: A qualified HVAC technician can clean the internal furnace parts and inspect the furnace for any potential problems.
  • Change the air filter regularly: A dirty air filter can restrict airflow and cause the furnace to overheat.
  • Make sure the furnace is properly ventilated: The furnace should have adequate ventilation to prevent overheating.
  • Be aware of the signs of a gas leak: If you smell gas, turn off the furnace immediately and call a qualified HVAC technician.

A burnt dust smell that only lasts a few hours is not bad. Any other burning smell could indicate a serious or even dangerous malfunction. Don't ignore it or try to fix it yourself. Instead, call Bannister Plumbing & Air immediately and we will send an experienced professional to identify the smell in your furnace.