Your furnace is an essential part of your home that, even though you might not think about it too often, becomes one of the most valuable appliances during winter. Don’t find yourself without a furnace this winter, be on the lookout for signs that your furnace might not be working properly.

One of the most obvious signs that there’s something wrong is a strange smell coming from your furnace. According to the smell, it can indicate different problems, which vary in seriousness. It can be hard, however, to diagnose the issue on your own, so here’s a guide to help you figure out what some types of smell mean.

From this article, you will learn about the causes of furnace smells as well as what to do in such a case.

Which Smells are Harmless?

Some odors coming from your furnace are harmless, but that still doesn’t mean you should just ignore them. If the smell is faint, or if it dissipates after a few hours, there is no cause for concern. However, if it lingers for more than a few days it could mean your furnace needs cleaning.

If there is a musty smell, it could indicate that moisture is trapped inside your furnace or, if the smell lasts longer, that mold is growing inside your furnace. Burnt dust is another common, but harmless smell; especially if your furnace is located in a basement. Dust can accumulate while your furnace is turned off in the summer, and then burn when it’s turned back on in the winter. Once the dust burns, the smell should go away.

You can also smell burning oil. It usually means that your furnace filter is clogged and that should make the smell dissipate. You should replace your filter at least every three months.

Finally, another smell that can come from your furnace is the smell of dirty socks. Yes, you heard us! The smell of dirty socks can indicate bacteria build-up in your furnace often caused by excess condensation. If the smell doesn’t linger, it’s harmless.

Which Smells are Harmful?

Some odors, on the other hand, can indicate a serious problem in need of professional intervention. If you smell smoke, it may indicate that your furnace’s chimney is blocked and that your furnace is venting smoke through your air ducts instead. A burnt electrical smell usually indicates that the inside of your furnace is too hot, damaging rubber or metal components.

Also, chemical smells, particularly the smell of formaldehyde, can mean that the heat exchanger in your furnace is cracked. The heat exchanger is responsible for moving heat from the combustion chamber into the plenum. A broken heat exchanger is a huge fire hazard and could even cause your furnace to leak carbon monoxide throughout your home.

Finally, a rotten egg smell means there is most likely a problem with your furnace’s natural gas supply. Though natural gas is naturally odorless, suppliers treat the gas so that it has a strong rotten egg smell, and gas leaks are more easily detected.

Gas leaks can result from various issues, underscoring the importance of having a licensed HVAC technician inspect your system.

Should you detect such odors, promptly shut off your gas supply using the shutoff valve if it can be done safely. Exit your premises immediately and contact 911 along with your gas company. Exposure to natural gas can lead to symptoms such as:

• Headaches
• Dizziness
• Nausea
• Vomiting
• Eye and nasal irritation
• Breathing difficulties
• Skin issues necessitate urgent medical attention if experienced.

Without proper care, natural gas exposure can be life-threatening.

Occasionally, a rotten egg smell from the furnace might not be indicative of a furnace issue but rather problems with sewer lines. If your furnace emits a sewer-like odor, it could be due to a dry sewer trap near the furnace. This can be addressed by pouring water down the basement floor drain. Alternatively, it may signal a sewer leak, requiring assistance from a specialized sewer line company to resolve the issue promptly.

Adverse Effects of Neglected Furnace Maintenance

Failure to promptly address any of the serious odors described above could lead to more significant issues in the short or long term. Properly maintaining your furnace helps mitigate these problems and prolongs its lifespan. The following describes some of the risks associated with inadequately maintained furnaces and how to respond when odors are detected.

Carbon Monoxide Leaks

Approximately half of all household furnaces in the U.S. are powered by natural gas, which typically contains carbon-based fuels like methane. Carbon monoxide, a colorless and odorless gas produced from burning carbon-based fuels, can cause minor symptoms such as headaches but can be fatal in high concentrations.

Normally, gas furnaces emit small amounts of carbon monoxide, which are safely vented out through the ventilation system when the furnace is properly maintained. However, inadequate maintenance can lead to increased levels of carbon monoxide inside the home, posing a serious health risk. If you detect unusual odors, it’s crucial to have a professional inspect your furnace to prevent carbon monoxide poisoning. Regular maintenance checks are essential to ensure proper furnace function.

Gas Leaks

A gas leak from a furnace can potentially result in a fire or explosion due to the highly flammable nature of the gas. Lack of maintenance can cause cracks to develop in the gas line over time, allowing gas to seep into the home. As mentioned earlier, a gas leak is often characterized by a rotten egg smell or a hissing sound. If these signs are noticed, evacuate your home immediately and seek professional assistance to assess the furnace.

Home Fires

Aside from gas leaks, home fires can also occur due to malfunctioning furnace parts, dust accumulation, and nearby combustible materials. Malfunctioning components, along with dust buildup and loose items, increase the risk of fire. Regular furnace maintenance is crucial in preventing such incidents.

What to Do if There is a Weird Smell From the Furnace?

For most harmless odors, you can usually expect them to dissipate after a short time. If it’s burning oil you smell, then you should replace your furnace filter. For a dirty sock smell, clean and/or replace the air filter.

If the smells linger more than a few days, then it’s time to call in the professionals as the cause could be a bit more serious. When it comes to harmful odors, you should turn off your furnace when you first detect those smells. For the smoke smell, call a professional to clean your chimney; however, if the smell is too strong or the smoke detector goes off, it could be necessary to evacuate your home while professionals investigate.

When dealing with a chemical smell, it could come from a broken heat exchanger, which is a fire hazard and could also cause a carbon monoxide leak in your home. In that case, evacuation is necessary before even calling a professional.

What you need to remember is that if you find that any smell persists, it’s best to not take any chances with your health and safety, and to call an HVAC expert. It usually won’t take much to fix the problem; a simple filter change or clean-up will suffice, but you’re better safe than sorry!

Concerned about the weird smell from the furnace? Then consult the McMillin Air manager by phone to solve the problem: 623-432-5202.