Why Your Home Smells Weird When the Heat Turns On And What Is Normal vs Not
It is November. The temperatures dip, you switch your thermostat from cool to heat, and suddenly your home smells like:
• Burning dust
• Wet dog
• A musty basement
• Something metallic
• Something you cannot quite identify
Before you panic, take a breath. Strange smells are very common when you turn on the heat for the first time in the fall. Some smells are completely normal and others are a sign that your system needs professional attention. Here is what is normal, what is not, and when to call Aaspen HVAC.
1. A Burning or Hot Dust Smell
This one is completely normal.
Why it happens:
Dust collects on the heating elements during spring and summer when your system is not in use. When you turn the heat on for the first time, the dust burns off and creates a warm dusty smell.
How long it should last:
Anywhere from a few minutes to about an hour.
When to be concerned:
If the smell continues longer than a couple of hours, your system may have airflow issues or a clogged filter.
Quick fix:
Replace the air filter. If the smell continues, schedule a tune up.
2. A Musty or Wet Dog Smell
This can be normal at first, but it can also indicate a larger issue.
Why it happens:
Moisture can build up inside your ducts or system components, especially after humid weather. Moisture creates the right conditions for mold or mildew to grow.
When it is normal:
If your AC was used recently, a faint musty smell may appear briefly when switching to heat.
When it is not normal:
If the smell lingers or gets stronger, there may be mold inside the ducts, drain pan, coils, or filter.
This one should be handled by a professional. Breathing moldy air all season is not safe for anyone.
3. A Metallic or Electrical Smell
This is not normal.
Possible causes:
• Overheating furnace components
• Damaged wiring
• A failing blower motor
• An overworked system
What to do:
Turn the system off immediately and call Aaspen HVAC. Electrical and overheating issues can be dangerous.
4. A Burning Plastic or Chemical Smell
This is another smell that is never normal.
Possible causes:
• Melting insulation
• Electrical problems
• Overheating parts
• A foreign object near the heat source
What to do:
Turn your system off and call for service. Do not wait to see if the smell disappears.
5. A Rotten Eggs or Sulfur Smell
This is very serious.
A sulfur or rotten egg smell typically indicates a natural gas leak. The gas company adds the sulfur scent to help homeowners detect leaks quickly.
If you smell rotten eggs:
• Turn off your furnace
• Leave the home
• Call your gas company immediately
• After the gas company clears the home, call Aaspen HVAC
This is not a situation to delay or troubleshoot yourself.
6. A Sweet or Chemical Smell
This can indicate a cracked heat exchanger, which can lead to carbon monoxide risks.
Carbon monoxide itself has no smell, but overheating components associated with a cracked heat exchanger can produce a sweet chemical odor similar to paint or formaldehyde.
What to do:
If you smell anything sweet or chemical while the heat is running, the system needs repair or replacement right away.
The Bottom Line: Some Smells Are Normal and Others Are Not
Normal smells:
• Light burning dust
• Slight dusty scent
• Brief mustiness
Not normal:
• Persistent musty or moldy odors
• Burning plastic
• Electrical or metallic smells
• Sulfur or rotten eggs
• Sweet or chemical odors
If you are unsure, it is always better to be safe and schedule a professional inspection.
Aaspen HVAC Will Get to the Source of Any Furnace Smell
Our team will inspect your furnace, determine the cause of the odor, and make sure your home stays warm, safe, and healthy throughout the season.
If repairs or a replacement are needed, we offer flexible financing options to make the process stress free and affordable.
Call Aaspen HVAC at 845-590-6902 or schedule service online today.
Your comfort and safety come first.
