Can An Electric Furnace Produce Carbon Monoxide?

Electric furnaces are extremely difficult to produce carbon monoxide with because of the equipment that it uses. An electric furnace uses an enclosure completely sealed from any outside environment, meaning that no oxygen can enter the chamber and be used for combustion reactions.

Without oxygen present in the system, carbon monoxide cannot be produced by reacting to any materials in an electric furnace.

Even if carbon monoxide is produced by the reactions present in the system, it will immediately be removed from any “combustion chamber” and brought into a cooling chamber that uses water to remove all heat energy from the gasses.

This process ensures that no dangerous gases leak out into the surrounding environment, which can happen during the heating process where carbon monoxide is created.

So, an electric furnace cannot produce carbon monoxide by the very nature of its design and the materials present in it.

Do All Furnaces Give Off Carbon Monoxide?

While most furnaces are gas-burning appliances, not all of them produce carbon monoxide. Only gas-burning furnaces can produce carbon monoxide.

Electric furnaces cannot produce carbon monoxide because they do not burn anything at all to create heat. They pass an electrical current through a metal filament, heating it and making heat for the house.

The coils that make up the heating element of an electric furnace should never overheat, making them unable to reach the high temperatures required to produce carbon monoxide. 

Also, read how to tell if your furnace is gas or electric

What Causes Carbon Monoxide from Furnace?

Carbon monoxide is a byproduct of gas-powered furnaces’ combustion process. The majority of the carbon monoxide produced by your furnace is confined to the heat exchanger’s walls.

The gas is sent through your furnace’s flue pipe and safely vented out of your home when your unit is operating correctly.

Fractures may cause a gas heater with a leaking carbon monoxide exhaust in the flue supply pipes or the heat exchanger. These cracks can occur for various causes, and when they do, carbon monoxide might escape into your property’s air, posing a significant health risk, including death.

Blocked pathways caused by clogged filters, which lead to the accumulation of CO, can result in carbon monoxide leaking into the house. Additionally, if your furnace was not installed correctly, this also has a chance of happening.

CO finding its way into your environment is one of the most common blunders made during installation. For example, improperly built blower motor or ductwork can lead to problems while venting, and CO can easily end up in your air. This is why hiring certified specialists rather than low-cost labor is critical.

How to Tell if Your Furnace is Leaking Carbon Monoxide

Because it’s known as the “silent killer,” it can be really hard to tell when your furnace is leaking CO. To protect your family, here are a few signs to look out for:

Alarming Symptoms – Some symptoms to look out for include:

  • Headaches
  • Dizziness
  • Nausea
  • Fatigue
  • Shortness of breath or difficulty breathing
  • Chest pain or chest tightness – This can resemble symptoms of a heart attack.

If someone in your household has these symptoms, it’s essential to call 911 immediately.

Heavy Condensation on Windows Near the Furnace – If you notice a lot of condensation building up on your windows near the furnace, that can be a sign that it’s running too hot and releasing CO.

Sooty Stains Around Your Furnace – If you run your hand around the outside of the furnace, and it comes back blackened with soot, that can be a sign of CO leakage. That’s not all; CO can also form a brownish-yellow color around the furnace. This is also something to watch out for.

Vividly Appearing Smoke, Fumes, and Soot – Everyone knows the normal airflow through a furnace by its appearance. If you or someone you know notices that the smoke, fumes, and soot coming out of the vents seems to be unusually dark, this can also indicate CO leaking from your furnace.

Overheating Smell – If your furnace discharges odors that are different from usual, this can also be a sign of CO leaking. If you notice an overbearing smell of running oil or fuel, this can be another sign to watch for.

Weak Flame – Finally, if the flame coming out of your furnace is yellow instead of blue, this could also indicate CO leakage. Here is how to fix yellow flame in furnace.

Signs of Carbon Monoxide Poisoning

As you may already know, carbon monoxide (CO) is an odorless, colorless, and tasteless gas. CO poisoning can cause flu-like symptoms at first that progress to confusion, blurred vision, loss of coordination, nausea, and vomiting. Exposure to small amounts of CO over long periods can lead to brain damage and even death.

If you have a gas stove, furnace, fireplace, or any other gas-powered appliances in your home, have them inspected right away for CO leaks.

Moreover, this is what you ought to do if you suspect CO poisoning:

  • Get everyone out of the house and into fresh air immediately
  • Call 911
  • Open windows to bring in fresh air Leave doors open as you leave to let air circulate

Carbon monoxide is fatal and has contributed to the poisoning deaths of nearly 13,000 people in the US every year. So, make sure you take all the necessary steps to prevent CO poisoning and act accordingly if it happens.

How to Fix Carbon Monoxide Leak in a Furnace?

The best approach to address carbon monoxide leaks in your home is to ensure no trace of CO goes unnoticed. Once you’ve detected a problem, you can only correct it.

Use the instructions below to repair a carbon monoxide leak in your furnace.

  • To keep track of contamination levels before and after dealing with the leak, install a CO detector.
  • Turn your furnace off if you suspect a leak.
  • Leaks from the flue gas line, heat exchanger, or vent system can be dangerous if not attended to accordingly. Visually examine all of these systems for flaws such as rusts, cracks, gasket leaks, and holes, then note them.
  • Because the eyes are subject to limitations, you mustn’t only depend on them alone to determine if there has been a leak. You can spray a penetrant dye like Magna flux over the suspected regions, then check the interior for leaks.
  • Replace every damaged component with a new one.
  • If you have a vent, make sure there are no blockages in the filters, which might cause CO to collect inside the duct. Additionally, all of the filters should be washed and dried.
  • Inspect the detector again to see if there are any more CO deposits after restarting your furnace. If they’re still there, it’s time to get a professional to do overall maintenance and a more comprehensive leak check.

Can Carbon Monoxide Come from a Furnace that is Off?

No. Carbon monoxide can’t come from a furnace that is off. Furnaces produce carbon monoxide only when the burners are fired. If there’s no fire, then there can be no CO produced.

So, there’s no need to be concerned about carbon monoxide when you leave the house and turn off your furnace.

Most, if not all, CO poisoning cases have occurred only when the furnace is fired up and running. However, issues can still arise even if your furnace is off but not appropriately vented.

This is because vents play a significant role in regulating CO emissions. So, even though the furnace is off and no fire is burning, your venting can still be a problem.


When air flows through vents that lack proper insulation, they can pull flue gases back into your home and force them to travel up through your ductwork. This can happen even when your furnace is off.

For this reason, it’s important to inspect your venting regularly. Ensure that they’re properly insulated and sealed so that CO can’t escape into your home or backdraft into your furnace.

You should also make sure there are no obstructions in the path of the flue gases when you fire up your furnace in the future.

Can a Dirty Furnace Filter Cause Carbon Monoxide?

Yes, dirty furnace filters can cause carbon monoxide. And here’s how that can happen:

Air filters are designed to prevent dust and debris from reaching your HVAC system. However, over time, these filters become clogged with dirt, forming a thick barrier of debris.

When your filter prevents air from flowing through your furnace, you risk having a serious issue known as restricted airflow. If there’s restricted airflow, the heat exchanger heats up and cracks. Hence, CO leaks into your house if the heat exchanger cracks.

Heat exchangers are made of different metals, including stainless steel, aluminum, and iron alloys. These metals can fracture when subjected to enough heat, allowing hot gases from the “combustion” process to escape through the heat exchanger.

When the steam created by the heat exchanger mixes with the air pushed back into your home, this becomes dangerous. The problem arises when these gasses, such as carbon monoxide are inhaled.

Final Thoughts

The bottom line is that an electric furnace cannot produce carbon monoxide because it is not in direct contact with the burning process. And to produce carbon monoxide, there has to be a fuel source.

If there’s one thing you should remember about carbon monoxide detectors, it’s that they can protect you if they are correctly installed and maintained.

And to make sure that it’s working properly, you should test it once a month to check the battery and CO sensor. Lastly, replace the detector every five years to keep yourself (and your family) safe from this silent killer.