Some of the most common questions we get at this time of year are how long do furnaces last and how to know when it’s the right time to replace a furnace. The honest answer is that the right time will be slightly different for everyone, depending on:
- Risk tolerance: are you willing to risk a sudden breakdown?
- Energy costs: how much of a burden are your monthly bills?
- Your budget. If you’re looking for a more affordable option, we provide Furnace Rentals in the Greater Toronto Area.
- Comfort situation: do you have warm or cold areas in your home, and do they bother you?
But there are some warning signs you should pay attention to in order to save the most money long term and avoid sudden breakdowns.
Life Expectancy Of A Furnace
In general, you can expect a well-installed, regularly maintained furnace to last about 15 years. Our climate is cold here in Toronto, and furnaces have to work hard for about 8 months every year. Make sure you know how to tell the age of your furnace before taking action.
There’s an advantage to shopping for a new furnace before it breaks down completely. It gives you time to decide on the right model and even take advantage of seasonal discounts or rebates. If it’s February and your furnace dies and you’re stuck, you may not get the best possible deal.
Older furnaces, however, are not nearly as energy efficient as newer models, which brings us to the efficiency question.

How To Tell It’s Time To Replace Your Furnace
1. You Need to Reduce Your Energy Bills
Technology has come a long way in the last 10 – 15 years, and huge improvements have been made in how much energy they use. In the 1990s, for example, furnaces averaged about 80% efficiency. Today, the legal minimum in Canada is 90%, and it’s common to find furnace models with a much higher rating than that. The EnergyStar program recommends replacing any furnace that is 15 years old for efficiency reasons.
In your furnace manual, there will be a number called an AFUE (annual fuel use efficiency) rating given as a percent. Compare that number to the efficiency of a new furnace, and you’ll get the difference in efficiency. When you apply that to your winter heating bills, you can see how much you would save.
Also, keep an eye out for sudden increase in fuel usage on your gas bill. If the price per unit has remained the same and so have your usage patterns, your furnace may not be working as efficiently as it used to.

2. Repair Bills are Adding Up
Just like your car, your furnace depreciates. Once your repair bills reach $600, it’s time to compare repair costs to the age of your furnace and decide if it’s worth it to keep making repairs.
For a newer, high efficiency furnace, a single $350 repair bill worth it. A 10-year old furnace may not be worth such a large investment. As a general rule of thumb, once repair costs reach half the cost of a new furnace, replacing definitely makes more sense.
3. Your Furnace is Making More Noise
As furnaces get older, they can start to make noises like pops and bangs. Aside from the annoyance, this could be a sign that parts are getting ready to fail. It can also mean that your ductwork is not sized correctly for your home.
If noise level is a concern for you, ask your technician about sound levels for any new furnaces you may be considering.
4. You See Signs of Rust, Cracks or Excessive Soot
These signs definitely mean that your furnace needs to be inspected, at the very least. The worst case scenario is that your furnace is a safety hazard.
Because your furnace burns fuel, it has certain natural byproducts that can be deadly, mainly carbon monoxide. Usually, these are vented safely up the vent, but if your furnace is older, there may be cracks or other flaws that mean gas is leaking into your home.
5. Your Furnace Cycling Pattern Changes
If your furnace is turning on and off more frequently, or stays on longer than it normally would to heat your home, it may be a sign that some parts are failing and others are working harder to make up for it.
6. Your Furnace Doesn’t Keep the Whole House Comfortable
Most homes have natural warm and cool spots, depending on where they are on the ground floor or another story, the number and size of windows, insulation quality, and even ceiling height.
If this bothers you, newer furnaces are much better at keeping a regular temperature, even if your home isn’t divided into multiple temperature zones.
It All Adds Up – Replace Your Furnace!
As you can tell, you need to weigh multiple factors together in order to make your decision.
If you need more information about what the options are for a new furnace, don’t hesitate to ask us for a free quote. You’ll love our no-pressure process, in which you receive everything in writing up front. You can read more about how we handle furnace installation here.
Want to learn more about making your furnace last longer? Here are some simple maintenance tasks any homeowner can do.