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My Furnace Overheating

Living in Canada, we experience cold and frigid winters every year, so, your furnace has to work extra hard to heat your home and with this comes the chance of your furnace overheating.

Most furnaces have a built-in safety feature which will turn off the furnace when the unit reaches a high temperature. Although these safety precautions are there, an overheated furnace being in your home is still not ideal for your family or your home. You may be wondering, how can I tell that my furnace is overheating? Below you will read all you need to know about your furnace overheating and how you can fix the problem.


Signs That Your Furnace is Overheating

  • Strange noises or humming being produced by the furnace. These sounds are a sign that the blower motor is trying to start but there is something stopping it from doing so. When the motor is trying to work but is unable to, it creates an excess of heat which results in the noises that you hear.
  • A burning smell coming from the vents. This smell can often be confused with the smell that is produced when you haven’t used your furnace in a long time, like when you turn on your furnace for the first time in the winter season. Although, when the smell is to do with your furnace overheating it will be followed by the furnace turning off on its own.
  • Furnace cycling off without starting up again. As previously stated, most modern furnaces have a built-in feature which allows them to shut off on their own when they get too hot. If your furnace doesn’t restart after doing this and requires you to reset before it operates again, this is a likely sign of constant furnace overheating.


How to Fix the Problem

We do not recommend for you to try and fix your overheating furnace on your own as with its many electrical and mechanical components it would be very easy to make a mistake which could end up being both dangerous and detrimental to your home and HVAC system. If you’re experiencing a problem with your furnace overheating, or have a broken down furnace, it would be in your best interest to call a professional HVAC technician to assess and fix the problem instead of you trying on your own. An HVAC technician will be able to find the problem and provide the most simple solution with ease. What you can do when you’re noticing a problem regarding your furnace overheating is to simply turn off the power to the unit and make a call to a furnace repair company to handle the rest for you.

Reasons For Your Furnace Overheating

There are many possible reasons behind why your furnace is overheating. Many of these causes can be avoided with regular furnace maintenance.

Short cycling: Short cycling is when your furnace turns off early into its heating cycle and has to turn on and off repeatedly. A short cycling furnace system puts stress on the motors and may result in the system breaking down. If you have a short cycling furnace system, contact a professional to evaluate the issue before the system burns out.

Mechanical Failure: The furnace’s fan motors and wiring can become stressed and result in failure and overheating. The moving parts of your furnace need to be well maintained to prevent early failure.

Restricted airflow: When the air flowing through your ducts is blocked from moving freely, it stays trapped in the system and causes the system to overheat. This problem can be fixed by simply changing your furnace filter regularly and by ensuring that there is nothing blocking the air vents around your home such as furniture or rugs to allow the air to circulate without any obstructions.

Dirt buildup: When a furnace filter is riddled with dirt it can cause many problems such as restricted airflow and allows for dirt to build up on other furnace components. This can be especially harmful to your HVAC system when there is a dirt buildup on the blower motor. If the blower motor can’t vent itself, it will overheat.

Outdated/Old age: Old furnace components are prone to wearing out and lead to furnace failures and overheating. An older furnace unit may not include the safety shut-off feature which was mentioned previously, so you will need to be especially careful with units using older technology. Older furnaces are not nearly as energy efficient as their modern counterparts are, which mean that installing a brand new unit to replace your old one can actually save you money on your utility bills. When your furnace is around the 15-20 year old range you should consider a replacement because if it hasn’t experienced failure yet, it will in the near future.


An overheating furnace is more than just a minor inconvenience to your home, it can be dangerous to you and your family. Contact a professional to evaluate the problem and provide you with a simple solution before it’s too late. DeMark Home Ontario is here to assist you with all your heating and cooling needs. If you’re having problems with an overheating furnace, call us today at 647-847-2998 or fill out online request form and one of our friendly staff will get in touch with you as soon as possible.

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