Furnace Troubleshooting – Oil Furnace Smells Like Exhaust – 2021 Guide

| Last Updated: June 10, 2021

A good-quality furnace is vital for survival and comfort in the cold winter weather. Without one, we would be lighting wood fires to keep ourselves warm. Unfortunately, furnaces require regular homeowner upkeep and professional tune-ups to perform efficiently and smoothly. 

Even with proper maintenance, furnaces can develop problems or break down, thus hindering regular functioning. There are various indicators that your furnace is not working optimally, such as strange noises and ever-increasing energy bills to performance issues. However, one vital sign of an ongoing or impending furnace issue is strange furnace smells.

It is very important to pay attention to these odors as they are a sign that something is not right. Here we will talk about why your oil furnace smells like exhaust and how you should deal with this problem.   

Photo credit: actionfurnace.ca

Why Does My Oil Furnace Smell Weird? 

There is a strong possibility that when you turn on your furnace the first time after summer, you might experience some strange smells. Common furnace odors include:

Burning Dust Smell

You might smell burning dust the first few times that you start your furnace in winter. This is completely normal and will go away within a few days. However, if it should persist, you should change the air filter.

Metallic Smell

In case there is a metallic smell coming from your furnace, there is a chance that a component inside is overheating. This smell will be somewhat similar to the smell of burning rubber, oil, or plastic. In such a case, you should immediately shut off the furnace and call a professional. 


Sometimes, the furnace chimney or the exhaust vent becomes blocked, and the combustion exhaust is forced into the ductwork. If you notice a smokey smell coming from the furnace, turn off the furnace immediately and open a few windows. If the smell persists, leave your home temporarily and wait for a professional to identify the problem. 

What Causes a Fuel Oil Smell When Furnace Runs?

If you experience oil smells coming from your furnace, then you should inspect the unit quickly to see if flames or any smoke is coming from it. In such a case, you should shut off the unit immediately and contact a professional. The following are some of the common reasons that can cause oil smells to emit from your furnace:

Faulty Burner

Sometimes, if a burner gets too much air, it might burn too cold or too big and not actually burn all the oil going through the flame. This could cause oil smells and result in insufficient heat. A simple adjustment of the burner can easily take care of this problem.

Photo credit: rural-fuels.com

Cracked Heat Exchanger

This can be caused by a burner assembly that is not adjusted properly or using the correct-sized nozzle. This is a serious problem and will require you to buy a new furnace entirely. 

Delayed Ignition

Unignited oil droplets remaining in the furnace could create a dense fog. When they do ignite, the unburned oil lights up at once, causing a large hazardous fire. If your unlit furnace smells like oil even when it is unlit, then do not light it and seek assistance from experts.  

Incomplete Combustion

The oil may not be able to combust properly, and these dregs could cause the smell to linger.  

Dirty or Cracked Heat Exchanger

A heavily smoking heat exchanger can become choked and will need to be cleaned in order to eliminate odors. Also, if it is cracked, then fumes may escape through these cracks, causing oil smells to prevail in your home.  

Recently Filled Tank

It is common to experience oil smells if your oil tank has been filled recently. However, it would dissipate over time.

Initial Furnace Use

When you turn on your furnace for the first time after summer, it is perfectly normal to experience oil smells. However, it will soon go away.

Clogged Furnace Filter

A blocked air filter can release oil smells throughout your home. Make sure to check the HVAC air filter regularly. Air filters need to be changed frequently; however, if replacing it does not solve your problem, then call a furnace repair service.  

Crowding Around the Furnace

If there are objects around the furnace, then there is a chance that they are heating up and causing smoke. Make sure that there is adequate space around the furnace to ensure proper air ventilation.     

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Is the Exhaust Smell from My Oil Furnace Dangerous?

Many homeowners are concerned about the effects of exhaust smells on their health, particularly if their oil tank is in a closed space, such as the basement. Heating oil is relatively safer to heat as compared to natural gas; that is why being exposed to small amounts of fumes is not dangerous. Moreover, heating oil does not explode in case of a leak. However, it is best for your health to avoid exhaust fumes. 

In case you are exposed to exhaust smell for a short period, any repercussions that you might feel will disappear as soon as the smell disappears. However, make sure that you are not exposed for long as this could cause serious health issues. 

When Should I Call in the Professionals?

Unexpected furnace repairs are inconvenient and costly. However, there are times when ignoring the problem or attempting a DIY solution can be quite risky. Some of the common problems when you have to call in professional are:

Gas Smell

The smell of gas can be quite a serious issue. If you do smell gas, leave the area immediately and call in a professional. Other signs of a gas leak are roaring, hissing, or whistling sounds, dead or dying vegetation near gas piping, damaged connection to gas appliances, bubbling water, or unusual soil movement. Don’t take any chances when it comes to natural gas and call a professional promptly. 

Regular Maintenance

An HVAC system plays a vital role in the safety, comfort, and value of your property; therefore, it should be kept in tip-top shape. Investing in regular preventative maintenance not only ensures a safe home but also extends the life of your furnace.    

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Combustion Issues

It is best to engage the services of a qualified HVAC technician to take care of any problems related to the heat-producing function of your furnace. An unexplainable increase in your monthly utility bill or unusual odors coming from the furnace could be a sign of a combustion issue. 

Malfunctioning furnace combustion usually results in higher CO emissions; therefore, it is best to get your furnace inspected by a professional right away. 


Preventive maintenance can help eliminate many problems that can cause strange or exhaust-like smells. Don’t risk the safety of your home and your family and eliminate all the reasons that can cause a dangerous accident. Have your furnace professionally inspected and cleaned before the winter season. 

Moreover, if you experience exhaust smells around your home, then call a professional quickly. They have the knowledge, experience, and skill to get to the root of the problem and resolve it quickly.   

People Also Ask

It is good to have as much information about furnaces and the problems related to them as possible as this will help you solve them quickly and efficiently. In addition to the above information, answers to the following questions will help homeowners immensely:  

Why Would a Fuel Oil Furnace Smell Like Kerosene?

The most common cause of kerosene smell from a furnace is usually the presence of petroleum products such as oil or paint. When traces of natural gas present in the air mixes with drying paint, it produces a smell that is similar to kerosene. However, it is not dangerous, and you can get rid of it by thoroughly airing out your home.  

What Does Furnace Oil Smell Like?

Furnace oil is biodegradable, extremely stable, contains no carcinogens, and smells like oil. The fumes from furnace oil are non-toxic and do not pose a threat to your family’s health. Although the smell can be unpleasant, it is not dangerous, like smelling gas in your home. Home heating oil is a wise choice for your home, as it is the safest fuel available. 

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.