Never Ignore These Dangerous Furnace Smells

When you turn on your heater during a cold front, do you have to deal with smelly air coming from the vents? If the answer is yes, your heating system needs some help! One of the main indicators of needed furnace repairs is abnormal odors coming from your system. If your nose senses something off, don’t suffer through it!

Smells like rotten eggs, burning electrical, or chemicals coming from your furnace should never be ignored, because they could be signs of a serious or even dangerous problem. While it’s normal to notice a dusty burning smell the first time a furnace runs in the winter, if the odor continues, it should also be checked out by a professional.

Everyone who owns a home or building with a furnace needs to take specific precautions to maintain the safety of their family and property.

Regular maintenance and routine inspections are invaluable for keeping your heater or furnace in optimal (and safe!) working condition. Common issues that can arise with your heating system are frequently detected by unusual or unpleasant odors wafting from your heating vents. It is unwise to disregard odd aromas around your furnace or vents. Below, we discuss some of the smells that may signal a problem that requires evaluation by a professional.


Rotten Egg Smell

The most obvious and serious odor you may notice from your furnace is the rotten egg smell that indicates a gas leak. Natural gas is an odorless, colorless gas, so it’s nearly impossible to identify in its natural state. This is why manufacturers insert a chemical into the gas that is scented. If the system works properly, the gas is contained far from your breathable air. However, if a malfunction occurs that causes a crack or weakness between the combustion chamber and other areas, you could experience a gas leak. If you notice a strong odor of rotten eggs blowing from your vents or in your home, you could have an extremely dangerous gas leak. Immediately leave the area, and then call emergency services!


Hot Metal Smell

This smell is kind of like a cross between the burning smell and an iron smell. It indicates hot metal, which suggests that your furnace has an electrical issue, or could potentially overheat. This is not an issue that you want to tackle by yourself because it can be dangerous. Call the experts at Aire-Tech.


Plastic Smell

A smell like melting or burning plastic is usually just that, a piece of plastic next to your furnace that is burning from the heat. This often happens when a child or pet leaves their toy near the furnace. If you can spot it, you can remove it, just be careful about burning your hand on the plastic or the furnace itself.


Burning Electrical Smell

Another alarming odor you might smell from your vents is a burning electrical smell. To be clear, there is one time a slight burning odor that will occur when you turn the heater on for the first time at the beginning of the season. The sudden heat will start to burn off a collection of dust that has accumulated. This odor should fade within a few hours.

If you ever smell harsh burning, this is a problem! Shut down your system as soon as you can to prevent any further damage. The motor can burn itself out or the system can overheat, causing certain materials to burn or melt within the unit. You will need a professional to locate the source of the smell and ensure there is no risk of fire or further damage.


Chemical Smell

A chemical odor like formaldehyde could be a sign of a cracked heat exchanger. This is another serious problem, because it can allow carbon monoxide gas to circulate through your home’s ductwork. Carbon monoxide detectors should be installed on every level of a home, especially near the furnace, because the gas is odorless and colorless. If you notice a chemical smell coming from your furnace, call an Aire-Tech professional to inspect the unit as soon as possible.

Dusty Burning Smell

A dusty burning smell when you first turn on your furnace for the season is common, and usually nothing to worry about. Dust and dirt accumulates during the summer while the unit is off, and the smell will usually go away a few hours after the furnace starts back up.

If the smell lingers, try changing the furnace filters; if that does not get rid of the dusty burning smell, it is time to call for service. It could just be that your furnace needs a deeper cleaning, or there could be a more serious issue. Either way, it is best to play it safe and have a professional take a look.


Moldy Smells

We all know the sour smell of mold, but smelling it from your HVAC system is a really bad sign. Mold thrives wherever there is moisture — including inside your heater or air ducts. If you keep smelling moldy odors from your vents or around your heating unit, you could have a mold invasion. While mold may not seem like a big deal, it can actually affect your health if you are exposed to it for a long time. Additionally, as long as one mold spore is left or missed after cleaning, it can grow back. This is why you might need a professional to evaluate the extent of the mold growth and recommend professional cleaning.



If you experience a smoky smell coming from your furnace, immediately turn the furnace off and open your windows. This may occur when the furnace chimney (also called a “flue pipe” or “exhaust vent”) is blocked. The furnace’s combustion exhaust has to go somewhere, so it is forced into the ductwork.

If the smell is faint then open a window to ventilate and call a professional to schedule a service. If the smell is sudden or strong, you may need to temporarily leave your home and wait for a professional to come and identify the source of the smoke.



Prepare Your Furnace for the Winter Season

The coldest season of the year is almost here, and sitting by the fire won’t be enough to fight against the freezing weather conditions. It is important to make sure that your furnace system is ready for the winter cold.

How do you make sure that your heating system is ready? Here are a few simple tasks to prepare your furnace for what should be a season of high usage:


Inspect Your Thermostat

The first thing you need to do is check the condition of your thermostat. It is crucial to switch the thermostat from cooling to heating before the cold season sets in. To do this, set the temperature slightly higher than the room temperature and wait to feel if the heat kicks in the first minute or so. A programmable thermostat can save you the work.

If it does not work, check the connections to ensure that the power source to the system is turned on. You can also pull off the cover and inspect the wiring for any loose connections. If everything seems okay and the thermostat is still not working, call a professional.

Your furnace might have suffered damage to the blower, heat pump, or fan. Unless you have received training and can competently examine the cause for the malfunction on these parts, don’t attempt any do-it-yourself repairs.


Change the Air Filters

You need to replace your air filters at least once every season to make sure your furnace is working optimally. The U.S. Department of Energy even says that replacing air filters is the most important maintenance task if you want to keep the efficiency of your heating unit.

It is easy to find replacement filters at the hardware store, but be sure you have the necessary information before going there. You need to know the exact size and type of your air filter because an ill-fitting filter cannot just lead to inadequate heating, it can completely damage your system altogether.

Clean the Vents

As with the filters, the vents also accumulate debris and dirt over time. If the buildup becomes significant, the openings become clogged and can trap heat inside, causing problems. You can eliminate these issues if you clean the vents regularly.

A wet cloth is enough to clean the dirt and dust particles on the surface. The purpose is to ensure that nothing is blocking airflow. It is also crucial to check whether the air duct seal needs changing to ensure that the air circulates evenly throughout your home.

Test Your Furnace Before You Need It

It is a smart move to check if your gun has bullets before jumping to a duel. The same applies to your furnace, it is important to test if it is working before the winter season arrives so that if it isn’t, you’d still have time to contact a professional to repair and service your heating system.

Common indicators that your furnace might need professional assistance are abnormal sounds such as banging and rattling, a malfunctioning thermostat, and an un-ignorable lack of heating effects.



Final Thoughts

Abnormal smells coming from a furnace could be one of the signs of a failing or damaged system. No matter what type of furnace or heating system you have, never ignore furnace odors. In a vast majority of cases, they are a sign that something is not working the way it should.

If your system needs repair or inspection before winter, call us on 951-926-1002. You can also visit our Contact page and complete the contact form.