Strange Furnace Smells That Need Immediate Attention

May 04, 2022Back to blog
Why does my furnace smell funny

Unusual or unpleasant odors from your furnace are a major sign that your heating system may be having technical problems. This can be dangerous if not given immediate attention, which is why you should call in a qualified HVAC technician to address the issue as soon as possible.

In this article, we’ll explore some of the most common causes of strange odors from your furnace and how to deal with them. Read on to learn more.

Why does my furnace smell funny?

Making sure your furnace receives its annual maintenance tune-ups, especially when preparing it for winter, is key to preventing issues and making sure your heating system operates as efficiently as possible all year long.

Here’s what you need to know about the different types of furnace smells:

New furnace smell

The odor of a newly manufactured furnace is completely normal. It is caused by the burning process of the protective coating which will eventually disappear. However, although it is new, it might still have manufacturing defects. In such a case, contact the manufacturer to fix the problems under warranty.

Burning smell

If your heating system hasn’t been used for quite some time, it may produce a burning smell after you turn it on. This is usually caused by the burning of dust that has accumulated during the idle months.

This burning smell usually goes away within a few hours. However, if the odor persists or is accompanied by smoke, turn your heating system off immediately and call your local HVAC technician for a check up.


Visible smoke or the smell of it in the house may indicate that your furnace is clogged due to dust and dirt build up. If this is the case, turn off your heating system and close your gas supply line immediately before calling in a professional to fix the problem. If the smoke is actually caused by a fire, get out of the house ASAP and call in the fire department.

Gas smell

Household gas is actually odorless. Gas companies add a smell similar to rotten egg or sewage smell so that a gas leak can be detected. This is an obvious indicator of danger. If this situation occurs, leave the house immediately. Call a professional HVAC technician for a thorough inspection. Do not reenter the house until it’s safe.

Smell of burning plastic, rubber or metal

The smell of burning plastic, rubber or metal could mean that the heating component is overheating. Turn off your heating system at once because this could quickly result in a house fire. If there are no signs of fire in the unit, have it fixed or replaced by a professional technician.

Oil smell

The smell of oil coming out of air vents is usually produced by leaks or oil spills. To eliminate the smell, inspect the heating unit for signs of oil leaks. Also, change the furnace filters if they appear dirty. If the smell is still lingering, the cause might not be accessible and needs to be checked by a technician.

Chemical smell

A chemical smell is a major cause for concern. It typically stems from a broken heat exchanger that produces poisonous carbon monoxide that is dangerous to breathe. It can also lead to a house fire if not fixed immediately by a qualified HVAC service provider.

Damp smell

Over time, if not regularly cleaned, molds and mildews build up inside the HVAC unit and the air ducts. The moisture inside the system becomes a breeding ground for molds and mildew to multiply. This is the main reason why a damp smell is released inside the house. If you haven’t had your HVAC unit and air duct system cleaned in years, consider doing so now.

Who provides comprehensive HVAC duct cleanings in the Greater Toronto Area

Who provides comprehensive HVAC duct cleanings in the Greater Toronto Area?

As the leading provider of air duct cleaning services in Toronto, Sem’s Duct Cleaning is uniquely positioned to make sure your ductwork is functioning correctly and is free of unhealthy substances.

Our technicians keep up with the latest HVAC trends and use modern equipment to ensure excellent results every time. Give us a call today if you’d like to ask further questions or book our service.