Why Does My Furnace Smell Bad? 4 Dangerous Reasons

Woman holding nose because her furnace smells bad

HVAC systems can naturally emit odors that you may or may not notice, but there are some smells that indicate a serious problem that needs immediate attention. Certain furnace malfunctions cause distinct odors, such as:

  • Rotten eggs
  • Melting plastic, metal or rubber
  • Smokiness
  • Mustiness

Ignoring them or thinking you can fix them yourself can put your household in danger. If you’re asking, “Why does my furnace smell, and what do I do?” here are four distinct odors that are major red flags.

1. Furnace Smells Like Rotten Eggs

This smell is all too familiar to most people, but if you get a whiff of this in your home, it means there’s a gas leak and it may be coming from your furnace.

If your furnace smells like rotten eggs, get everyone out of the house immediately and call your gas company. Make sure to remain somewhere safe until the leak has been repaired by the proper technicians.

Once the leak has been repaired, bring in a trusted HVAC technician for a maintenance check. Even if your furnace needs additional repairs or a replacement to prevent a potential gas leak in the future, this is not a situation to take lightly. It’s crucial to keep your house both comfortable and safe for your family!

2. Furnace Has an Electrical or “Overheating” Smell

If you notice an overheating smell, this could mean that a motor function or other electrical functions in your furnace are getting too hot. These types of odors are typically be described as:

  • Burning plastic
  • Hot metal
  • Melting rubber

Unfortunately, these odors may indicate a component of the furnace is actually burning, and there’s a strong possibility for the problem to escalate and cause a fire.

This kind of smell is usually electrical-related and can be very dangerous. Turn off your HVAC unit and contact a technician as soon as possible.

3. Furnace Smells Like Smoke

Keep in mind that the smell of burning and overheating are not the same. Your furnace may emit a burning smell within the first 24 hours after starting it up for the season due to dust that has built up over the summer.

If you notice a burning smell from furnace vents lasting longer than 24 hours, then it’s time to take action fix the problem. Use the shutoff valve to turn off the furnace, and shut off the gas supply as well. When you call your HVAC repair technician, be sure to tell them the steps you have already taken and where you believe the problem lies.

4. Furnace Smells Musty

This is a smell you will notice more in your air conditioning unit due to the buildup of moisture that generates within the unit. It can migrate into the air ducts and cause mold, which will result in a musty, mildew-like smell.

This is a smell you will notice more in your air conditioning unit due to the buildup of moisture that generates within the unit. It can migrate into the air ducts and cause mold, which will result in a musty, mildew-like smell.

When mold develops in your air duct system, your family will inevitably be exposed to it, which can cause serious respiratory problems. However, this is easily fixed with a thorough cleaning of your air duct systems by your repair technician, who can also determine where the excess condensation is coming from and how to remedy it.

Fix the Problem

If your furnace is emitting a concerning odor, do not hesitate to contact the HVAC repair technicians at Sedgwick Heating! A team of repair technicians is available 24/7 to aid in any emergency heating or cooling situations.

Besides odor, there are other several other signs your furnace may need immediate attention. Read our blog, 5 Unmistakable Faulty Furnace Warning Signs, to find out what they are.