It’s almost that cold time of year when we start up those furnaces again. We have all been there, the first days of the heater started up and… – “what’s that smell !?”

There are many indicators that your furnace isn’t working right, from strange noises and performance issues to ever-increasing energy bills. However, one important warning sign of any furnace problems are the strange furnace smells that emit throughout your house. Not all these smells are directly caused by the furnace, but they may indicate a fixable issue all the same.

Here are some of the most common furnace odors and what they may mean:

  • Burning Dust or Smoke
      • A burning dust smell may emanate from the furnace once you start the furnace at the beginning of the winter season. This smell is completely normal and should go away within several days. However, if the musty smell persists, try solving this problem by changing out the air filter. If the problem persists after switching the air filter, it indicates a serious problem with the furnace. In such a situation, you should immediately turn off the system and call our team at AirTex
  • Metallic Smell
      • If you notice a metallic smell coming from the furnace, it might be due to a component inside the furnace overheating. In some cases, the smell will be like the burning of hot plastic, oil, or rubber. If you smell odors that suggest that something in the furnace is burning or overheating, you should immediately shut off the furnace and call AirTex for an inspection.
  • Rotten Eggs
      • The odor of a rotten egg or sulfur is another cause for serious concern. Utility companies put odor-indicating substances in natural gas, which is normally odorless. So, if you notice a potent rotten egg smell in your home, it could indicate a gas leak. You need to immediately shut off the gas furnace and call AirTex for an inspection of your system.
  • Mold or Mildew
      • A smell of mold coming from the furnace indicates a potential mold infestation inside the ductwork. You should not take mold infestation lightly. A mold infestation can degrade the quality of indoor air. It can cause people to suffer from flu-like symptoms, accompanied by sneezing and coughing. Here at AirTex we can work together on-air purification
  • Pet Odors
      • Sometimes, the smell of pet waste or hair will appear to emanate from the furnace registers. If you get a strong whiff whenever you turn on the furnace, it’s important that you inspect the floor level ventilator registers. Cleaning up the mess near the vent can solve the problem as well as changing your air filter.
  • Sewage
      • In case you notice the smell of sewage water emanating from the vents, it may be that an open sewer line or a broken wastewater line may be located near the system. A quick inspection of the external vents can help identify the source of the smell. If this is what is the determination, we have highly experienced plumbers we can recommend.


No matter what type of furnace or heating system you have, never ignore furnace odors. In a vast majority of cases, they are a sign that something is not working the way it should.

Call us at AirTex Heating and A/C we would be happy to come out and help you with any services you may need. 806-549-5973

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