Why Does My Forced Hot Air Smell?

Why does your forced hot air smell? Well, there could be a number of reasons for an irregular odor stemming from your HVAC system. Hopefully, this helps you identify an issue early so that you can better explain the situation to your local HVAC technician. 

  • Dusty or Musty Odor
  • Oily or Fuel Aroma
  • Sulfur or Rotten Eggs Stench
  • Identifying a Gas Leak
  • Call the Gas Company or 9-1-1
  • Dirty Socks or Gym Locker Room Stink
  • Burning Electric or Metallic Smell

By now, we have all heard the warning, “if you see something, say something.” It is an agreement between law enforcement and the general public to coordinate efforts in safety and security by encouraging citizens to contact the police if they notice anything out of the ordinary that may seem suspicious in a threatening manner. American Airflow would like to offer a slightly revised version that might help us ensure the safety of our customers in the same way. 

If You Smell Something, Say Something

“If you smell something, say something.” Of the five primary human senses, our sense of smell is probably the most beneficial to either preventing, or at least minimizing, a danger to your family, your home, or your system. If you encounter an abnormal odor emanating from your heating or air conditioning system, turn off your equipment immediately and call the appropriate technician. It is much easier to notice an unusual smell than it is to actually see a problem because the equipment is usually out of sight.

We will outline some of the most common smells that our company has experienced throughout our decade in business, but this is not a DIY how-to manual to help you diagnose an issue and solve it on your own. While of course there are things you can do to ensure that your heating and air conditioning equipment is performing efficiently, like joining a maintenance program like our American Airflow Comfort Care, it is important to remember that you should always call your HVAC contractor to report a foul odor. 

There is no reason to feel silly in trying to explain your concern over the phone because your local HVAC technician has most likely heard it before and will already have a few potential solutions in mind before he or she even walks through your door. “Dusty, musty, oily, electrical, rotten eggs, dirty socks, and locker room” are all common words or phrases that have been used over the years to explain a foul odor, so nothing you say will sound crazy to a contractor that has probably heard it all before. 

A Dusty or Musty Odor

The most common smell that may emanate from your furnace is that “dusty” or “musty” odor. That is most likely your heating system burning off the dust that has piled up on top of and inside the equipment over the course of the warmer months while it has been sitting there unused. The first cold day that motivates you to crank up the thermostat will probably smell for a few minutes while the dirt is burned off, but it should go away fairly quickly. If that dusty smell continues, be sure to shut off the system and call your local HVAC contractor. 

An Oily or Fuel Aroma 

An oily or fuel aroma can transpire from time to time if you have an oil burning furnace. If the smell is minimal and dissipates quickly, it could just be a few oil spills from a recent tank filling that is burning off. However, when all of the oil is not completely ignited as it passes through the burner, it could potentially create a fog that can smell like a dirty car engine. If the issue is not contained quickly, it could produce a large flame in the furnace and will emit an abnormal amount of smoke. If this happens, please be sure to turn off the machine and call your HVAC technician.

Sulfur or Rotten Eggs Stench

The smell of sulfur or rotten eggs is probably a familiar concept to most of us because it is a very specific odor that is quite unforgettable. In other words, you know it immediately when you smell it and you already know that there is definitely a problem. What you may not know is that the smell of rotten eggs is artificially added to your natural gas as a warning because gas is odorless. The sulfur-based chemical additive is called mercaptan and it is truly a vile smell, but it has saved countless lives for nearly a century. 

Identifying a Gas Leak

The United States government began requiring gas companies to add mercaptan as a safety feature to their odorless natural gas shortly after the devastating explosion at the New London School in New London, Texas, back in 1937, which killed more than 300 students and faculty. Odorless gas had been leaking from a tap into the enclosed crawlspace that ran the entire 250-foot length of the building, but without a smell, it went undetected. The spark that ignited the explosion came when an instructor at the school turned on an electric sander. 

Calling the Gas Company or 9-1-1

We know that natural gas is extremely flammable, but it can be harmful to you and your family in other ways if it is inhaled. Side effects of natural gas inhalation can range from dizziness, nausea, fatigue, to irregular breathing. It can be difficult to notice at low levels so if you smell even a faint whiff of rotten eggs, it is important to take it seriously. You should evacuate your home immediately and call your local gas company or dial 9-1-1 if it seems to be a more serious emergency. 

Dirty Socks or Gym Locker Room Stink

If the warm air coming out of your heating system begins to smell like dirty socks or a gym locker room, you may have a bacteria build up and potentially a mold problem. During the spring and fall seasons, the coils in your equipment will cool when the temperature drops. This often results in condensation which is the breeding ground for bacteria. We suggest a regular coil cleaning to our customers to prevent that bacterial build up and will usually solve the issue. You should also have your air ducts cleaned and sanitized to minimize any opportunities for mold or bacteria to thrive. 

Burning Electrical or Metallic Smell

Finally, if you notice an electric burning or metallic stench, your furnace could be overheating. One of our most common repairs every winter is a seized blower motor. The heat can melt any nearby wiring insulation and can produce electrical shorts that will produce that smell. Obviously, if this is not treated promptly by a professional, it can lead to a fire, so if you smell anything burning, cut off the power to the equipment and call your local HVAC technician. 

Call Your Local HVAC Technician

If you smell something, say something. American Airflow is here to help solve even the most foul smelling issues in your HVAC equipment. 

Frequently Asked Questions (FAQ’s)! 

What should I do if I smell gas in my home? 

If you notice the unforgettable smell of rotten eggs or sulfur in your home, that means there may be a gas leak. You need to open your windows and doors, evacuate your home, and either call the gas company or 9-1-1 emergency services. 

Why does my forced hot air HVAC system smell dusty when I turn it on? 

That could simply be dust burning off of the system after being dormant for a while. If the smell occurs every time it is fired up or it persists for more than a few minutes after ignition, you should contact your local HVAC technician to diagnose the problem.

Why does my furnace smell weird? 

Your hot air furnace should not smell weird and if you notice a strange odor when you turn on the heat you need to contact your local HVAC technician immediately.

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