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What your furnace smell might be trying to tell you

As humans, we have a particularly powerful sense of smell. While not as fine-tuned as some other mammals, our sense of smell tends to be much more accurate than we give it credit. So when your furnace kicks on and you swear something smells off as the warm air fills your home, chances are that you’re on to something. But it depends on what you’re smelling.

Typically, furnaces should be releasing a neutral smell — if it releases a smell at all. When furnaces begin releasing smells, it’s typically a sign that a portion of the furnace either needs to be cleaned, replaced, or worse, the entire furnace needs to be removed and the gas line inspected. So let’s break down the most likely smells coming from your furnace and how to deal with the underlying issues.

Musty and/or Moist Smells

A musty or moist smell, like a wet towel that’s been sitting out for too long or a damp dog smell, usually indicates potential mold or mildew growth. This could be due to general moisture leaking into the air ducts — potentially from an unresolved plumbing issue — or it could be that the furnace’s filter has been used past it’s recommended replacement time, and the clogged filter is causing condensation to gather in the ducts. 

No matter the cause, both mildew and mold growth are potential health hazards, and as the furnace continues running, there is an increased chance that spores from both are being spread around your home. Make sure to contact a professional to complete a thorough inspection, cleaning, and repair as needed, to ensure no spores or bacteria are spread through the vents and airways.

Old or Stale Smoke and Cigarette Smells

The culprit here is usually straight forward. The smell of old smoke or stale cigarettes generally comes from someone having smoked in the home — either currently, or a previous tenant — and the smell becomes embedded in the ductwork and filters. To remove the smell, a thorough cleaning of the airducts and vents is required, as well as changing out the furnace filters (which should already be done regularly, but just in case). This deep-cleaning should eliminate the odor fully at its source.  

Burning Smells

If there is a wiring malfunction, a mechanical issue, or a fluid leak, these all could create smells that are similar to burning or reminiscent of gun powder. In all instances, these types of smell are usually indicating that some part of the furnace itself is not functioning as it should, but that electricity is still connected to the worn down part — such as a worn out wire or a dying blower motor — which could lead to a more serious malfunction, or potentially a fire. As such, it’s important that the home’s furnace is disconnected, the power turned off, and a professional contacted for an inspection and repair immediately. 

Rotten Smell — Eggs or Otherwise

This smell is arguably the most unpleasant, and could indicate several issues — some more serious than others. 

First, you need to be able to determine if the cause is from a gas leak. If unsure about this possibility, it’s always better to play it safe. This means:

  • Avoid creating sparks or flames, and extinguish any immediately
  • Open as many doors and windows as possible
  • Turn off the gas supply, if you can
  • Evacuate the home, and contact the gas company

If a gas leak can be ruled out, this leaves the unpleasant possibility of a rodent issue. It is possible that an animal has tried to make either the ducts a new home, and instead, found itself trapped and passed away. This leads to a highly off-putting rotten odor of decay. While it’s possible to tackle this yourself, you would be forgiven for not wanting to do major dead rodent removal without the proper protective equipment and experience. Thus, removing an animal’s carcass is generally best left to professionals.

Pinpointing the type of smell is exceptionally helpful information to pass along to HVAC professionals when calling in with concerns. If you’ve noticed an odd smell coming out of your vents, ducts, or furnace, reach out to the professionals at Duane Blanton Plumbing, Sewer, Heating, and Cooling for help eliminating the issue. With over 30+ years of experience, the team at Duane Blanton have the knowledge and expertise to get to the bottom of any odd smell your furnace can produce, and find a way to fix it. Reach out to the technicians at Duane Blanton Plumbing, Sewer, Heating, and Cooling today, via phone at (815) 781-2567, or schedule quickly from your browser with their convenient online scheduling tool

Duane Blanton Plumbing, Sewer, Heating, and Cooling is proud to be a Bryant Factory Authorized Dealer, offering top-quality heating and cooling options that fit the home comfort standards that Duane Blanton customers value. The quality, comfort, and efficiency of Bryant Heating & Cooling Systems’ products naturally align with Duane Blanton’s drive to provide an exceptional customer experience for every home and budget. Ask a Duane Blanton Plumbing, Sewer, Heating, and Cooling expert today about the advantages of upgrading to a new Bryant Heating & Cooling system for your home!


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