When Does It Make Sense to Repair vs. Replace My Furnace?

Couple research replace or repair furnace

Does your furnace keep shutting off? Or maybe your furnace has broken down. Either way, when you’re faced with a sizable repair bill, you may be wondering if spending money on the repair is worth it. At a certain point, if you’re spending money, it may make more sense to invest in a new furnace.

Unfortunately, there isn’t a one-size-fits-all answer. There are several factors you’ll want to weigh in. Luckily there’s a good rule of thumb to help guide you: once the cost of repairs adds up to 50% of a new furnace purchase, definitely go for the upgrade.

For those of you who may be thinking, “that helps, but I need more information” here are some things to take into account when making your decision.

1. How Old is Your Furnace?

Our hard-working furnaces can be expected to last about 15 years, perhaps more if they were correctly maintained. Conducting furnace tune ups is worth it, they extend the life of your furnace. If your furnace is only a few years old, find out if the repair is covered under warranty – this will depend on the manufacturer, and it should be in your manual or other purchase paperwork.

If a furnace is “middle-aged” – around 6 or 7 years – replacing is an option if you’re faced with a very large repair bill, but not if it’s only a few hundred dollars.

Once the furnace is over 10 years old, start considering replacement at a lower threshold. This chart should help simplify things:


What complicates things is the potential cost of the new furnace. Depending on the size, efficiency, and comfort control, furnaces can cost a few thousand dollars or over $10,000 installed. It makes sense to get a few quotes if you’re seriously considering replacement.

2. What is Your Furnace Condition?

Every once in a while you see a beautiful vintage car on the road that looks great. But you can also see newer models that almost limp their way down the street. The same thing goes for furnaces.

Not all furnaces are made alike, and not all furnaces are installed or maintained alike. Sizing the furnace correctly to your home and taking care of the details during installation can make a huge difference in how long it lasts.

Just like your car, ideally, you have your furnace maintained, cleaned, and safety checked every fall. This will ensure combustion byproducts are fully removed and no failing parts are making your furnace work harder than it needs to.

Here are some warning signs that your furnace may not be in great shape:

  • More noise when the furnace is on, or different noises. Pops, bangs, creaking or squeaks should be treated with suspicion.
  • Rising gas bills when usage habits and fuel costs have stayed the same. This can mean parts are wearing out and your furnace’s efficiency is compromised.
  • Soot buildup around the venting stack.
  • Signs of rust anywhere.

If you’ve noticed any of these, mention them to your repair technician and ask for their assessment.

3. Is Your Furnace Safe to Use?

Your furnace may have developed a hazardous problem. A loud rattling noise, for example, could be signalling heat exchanger damage. A cracked heat exchanger will leak carbon monoxide. CO gas is colourless, odourless … and potentially deadly. Because a replacement heat exchanger is extremely expensive, you will be better off replacing the whole furnace instead.

4. Is Your Furnace Energy-Efficient?

If your furnace dates back to the early years of this century (or before), you’ll be surprised at how much energy efficiency technology has improved since then. Buying a new, energy-efficient furnace will cut your carbon footprint and save you money on fuel.

Once again, there’s a formula. Take the AFUE (Annual Fuel Efficiency Rating) of several new furnaces and subtract your existing furnace’s rating. To illustrate, 90% AFUE minus 70% AFUE equals a potential savings of 20% on your fuel bill.

5. Does Your Furnace Heat Unevenly?

When you have a room or two that’s always cold, your furnace might just be getting old… or it might have been sized wrong when you first bought it. Furnace replacement could give you a level of home comfort you once only dreamed of, especially when combined with multi-zone heating technology and a smart thermostat.

6. Can You Afford a New Furnace Right Now?

Furnace replacement may be the most appealing option. But at the moment, you might feel your budget will only cover the cost of repair.

Knight is here to help. We won’t pressure you to replace vs. repair your furnace. What we will do is explain your options and inform you of any special promotions and rebates available for new furnaces. In addition, we’ll offer you convenient, affordable in-house financing.

We will even provide area heaters to keep your home comfortable until your new furnace is installed, just as we did for this satisfied customer:

Customer Success Story: Knight Client Choose Furnace Replacement in Calgary

“On December 25th, I woke about 3:30 am to a very cold bedroom. After determining the problem was more involved than an extinguished pilot light or a broken thermostat, I looked online for furnace repair.

I was pleasantly surprised when Knight Plumbing answered. The agent was professional, courteous and sympathetic. She advised me they weren’t taking any appointments until after 8:00 am. At about 9:00 am, Geoff from Knight let me know he’d be able to come out and take a look. He was very open about the rates for the day, given that it was December 25th. At no time did I feel pressured to have him come by.

Geoff came to my house around 1:00 pm. His assessment determined that the blower motor on my 40-year-old furnace was shot and needed to be replaced. After hearing all my options (replace the motor today, replace it later, get a new furnace etc.), I opted to purchase a new furnace.

Again I didn’t feel any pressure from Geoff. He laid out all the options, told me about the Knight’s preferred customer program, walked me through different furnace brands, and gave me recommendations based on his expertise.

He told me that the office would not open until the 27th and that we’d likely be looking at the new year before my furnace could be installed. However, Knight would deliver area heaters if requested.

On December 27th, after a couple of cold nights (-25 to -30), I called to inquire about installation and some area heaters. Knight had four heaters delivered within 60 minutes of my phone call and let me know that my new furnace would be installed on January 2nd.

On January 2nd, I got a call from George letting me know he was on his way. George couldn’t have impressed me more. He was very knowledgeable and professional. He instilled confidence which put my mind at ease. The finished product looks great. George was very thorough, and I appreciated the fact that he takes pride in his work.

While I hope to not have any issues with my furnace, if I do Knight will be the first company I call. I would also not hesitate for one second in recommending them for any other HVAC needs.”

– Paul K, Happy Knight Plumbing, Heating and Air Conditioning Client

Knight Will Give You Expert Furnace Repair Or Replacement

As you can see, there’s a lot to consider, and generally, there will be more than one factor at play when you make your decision.

If you’re interested, you can learn more about our no-hassle furnace process. You can also read about our furnace maintenance services.

Learn Simple Things You Can Do to Help Your Furnace Last Longer >