Possible Reasons Why Your Furnace Might Be Smoking

A smoking furnace can be a worrying sign that something serious is wrong with your home’s heating system. Knowing the potential causes of smoking can help you take the proper steps to identify and resolve the problem before it worsens. 

In this blog post, we’ll discuss some of the most common reasons why your furnace may be smoking – so you can get your heating system running in top condition again.

1. Burning Electricals

The furnace’s built-in safety feature will often turn it off if it overheats. If the safety system fails, electrical fires may start. There is a severe safety risk here that needs expert attention.

Any foreign materials that have found their way into the furnace may burn if it becomes too hot. Additionally, smoke may be produced as a result of this.

2. Broken Exhaust

The exhaust, also known as a flue pipe or chimney, is responsible for venting the byproducts of combustion out of your home. A damaged or broken one causes a release of byproducts into the house instead of being correctly vented outside. 

This can result in smoke or even carbon monoxide being released into the living space, which can be dangerous and require immediate professional attention. It is essential to have your exhaust inspected and repaired or replaced if it is damaged. Having your furnace checked for carbon monoxide leaks and other potential issues that might cause smoke is also essential.

3. Dirt Buildup

You know how dusty your furniture becomes if it is not regularly wiped down, right? The same is true for your heating system. Air ducts and vents can acquire dust, grit, filth, and grime. When your furnace heats the air and pushes it through the ductwork, little dust may rise through the vents, but this is not smoke.

You should not be frightened if you sense a musty, dry odour.  Additionally, dirt and grit accumulation makes your furnace work harder to exchange heat, which costs you more money.

4. Clogged Oil Filter

The oil filter might become blocked with oil contaminants. When the filter fails to filter the oil adequately, the contaminated oil enters the furnace. This can result in smoke and an odour of burning. You should contact a specialist to inspect the furnace and replace the filter if necessary.

This could also be a wake-up call to move from oil to gas heating, which creates less smoke and burns cleaner.

5. Newly Purchased

When a furnace is constructed, the heat exchanger is oiled to prevent rusting. The oil is consumed when the furnace is first turned on. In most cases, the installers will run the unit long enough to burn off the oil totally, but a small quantity of oil may remain and ignite when the device is turned on.

The good news is that the scent of the oil is not offensive. Some think it smells sweet, like maple syrup. This form of smoke-producing combustion is harmless. It is a natural phase in the life of a furnace.


If you notice the smell of smoke coming from your furnace, don’t hesitate to contact a certified HVAC technician right away. A technician can identify and address the issue quickly to keep you and your family safe and help you keep your home warm and comfortable all winter long.

Legacy Heating is here for you if you’re looking for furnace maintenance in Edmonton and Calgary. We use only the best quality parts so that you can expect the best in our services.
Want further peace of mind, ask us about our Annual Maintenance plans. Contact us now!

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