Why Does My Heater Smell Bad? Main Reasons and Easy Solutions

September 09, 2024

The main cause of a burning smell in a heater is dust accumulation. If you’re turning your heater on for the first time since last winter, dust that has built up for months can cause your heater to give off a burning smell. This odor is often temporary and should fade within a few minutes to a few hours.

But is that the only reason for HVAC odors? Let’s take a look at the common reasons for a bad or burning smell from your HVAC system, what causes it, and when you might need to call a professional for the job. If you live in or around Memphis, Tennessee, Conway Services is there to help you with all your HVAC needs.

The Most Common Heating System Odors and Their Probable Causes

Every year, homeowners throughout the Memphis area turn on their heating systems for the first time since the previous winter. When the heat comes on right away, that’s a very comforting feeling. But for many local residents, that first blast of heat is accompanied by one or more foul odors that stubbornly refuse to just disappear. 

Dirty Sock Syndrome or Musty Odor

No, we’re not making this up. Dirty Sock Syndrome is an industry-wide term that accurately depicts the odor produced by a dirty coil inside a heat pump or central AC system. If your whole house suddenly smells musty or like a damp basement when you first turn on your heating system, chances are that dust and dirt have accumulated during the off-season. 

Solution: If dust is causing the smell, there is no need to worry. The dust will burn off, and the smell will fade. Let the heater operate for ten minutes or so. If the odor decreases, there’s no need to worry. If the smell continues, you should contact a professional.

Electrical or Plastic Burning Smell

Another common and familiar heating system odor is the smell of something burning. If your heater smells like burning plastic or electrical parts, a host of factors can produce that unpleasant burning smell from your HVAC. 

1. Foreign objects in the system

If you have baseboard heating, it’s quite possible that a hairbrush, a child’s toy, or one of countless other objects fell into one of the baseboard units during the warm weather months, just waiting to be “discovered” once the need for heat arises. In that instance, the smell will be localized, making it quite easy to uncover the source and cause. 

Solution: Turn off the heating system and carefully inspect the baseboard units for any foreign objects. Remove any items you find and restart the system to check if the smell persists.

2. Electrical or system issues

An electrical burning smell can also be produced by the furnace motor overheating, a cracked heat exchanger, or a faulty electrical connection. 

Solution: These are all serious problems that need professional attention. Call a licensed electrician who can diagnose the exact issue and safely complete any necessary updates or repairs.

3. Clogged air filter

An air filter needs to be replaced regularly. If your filter is clogged, airflow is restricted, causing the motor to work harder and potentially overheat.

Solution: Turn off the system and inspect the air filter. If it’s dirty or clogged, replace it with a new one. Make a habit of checking and replacing your air filter every 3 months (or as recommended) to maintain proper airflow and efficiency.

4. New system

Does a new system have a smell? Yes, it’s normal for a new HVAC system to emit a slight smell when first installed. The odor is often due to burning off residue or coatings when it is used for the first time. Fresh ducts and metal components can give off a metallic or “new appliance” smell.

Solution: Allow the system to run for a few hours to see if the smell goes away. If it persists for more than a day or becomes stronger, contact the installer to inspect for any issues.

5. Other potential causes

For gas furnaces, a gas leak typically smells like rotten eggs or sulfur, but a burning smell could also signify a problem with the gas burner or related components.

Solution: If you suspect a gas leak or smell rotten eggs, evacuate your home and call your gas company or emergency services immediately. For other burning smells, contact an HVAC technician to inspect the gas burner and related components. 

Sweet, Chemical Smell

If you’ve ever wondered what an HVAC leak smells like, it often gives off a slightly sweet, fruity odor. Some people describe it as having a faint chemical or acetone scent. 

Solution: If you suspect a refrigerant leak, turn off your HVAC system immediately and call a professional technician. Never attempt to fix a refrigerant leak yourself, as exposure can be harmful. 

How Do You Deodorize HVAC Vents?

Odors in HVAC vents that don’t fit any of the other descriptions above can result from mold, mildew, or dust buildup. To eliminate smells and maintain fresh air, follow these steps:

1. Clean and replace air filters: Dirty filters trap odors and decrease airflow. Replace them regularly.

2. Clean the ductwork: Have a professional clean your duct system to remove mold, mildew, and dust.

3. Install an air purifier: Adding an air purifier to your HVAC system can help neutralize odors.

4. Use a deodorizing spray: Lightly spray a deodorizing spray into the vents while the system is off.

5. Check for mold or mildew: If the smell is musty and you’ve already verified it isn’t from dust buildup on the heat exchanger, inspect the ducts and evaporator coils for mold growth. 

How Do I Get Rid of the Smell in My HVAC System?

If you haven’t already turned on your heating system for the season, we’d like to suggest a complete pre-season cleaning and inspection by an experienced and highly qualified heating technician from Conway Services. That way, we’ll discover the odor and root out its cause before the heating season gets underway. Memphis area residents can take advantage of our Pro Service Plan, which gives you two preventative maintenance visits per year.

If you’ve already turned your heat on and don’t know why your heater smells bad, contact Conway Services at 901-248-1961 or schedule online so we can troubleshoot the cause of your particular heating system odor and set things right again. No matter what your home heating needs might be, you can count on us for prompt attention and thoroughly reliable results. In fact, we guarantee it.