How to Know if You Should Repair or Replace Your Furnace

Ben Kissam
Written by Ben Kissam
Updated November 4, 2021
A Muslim mother is sitting on the couch with her daughter
FatCamera / E+ via Getty Images

An old, inefficient, banging furnace means it’s time to replace it—at least, most of the time

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

If you own your home long enough, you’ll probably have to replace your HVAC system to keep things comfy. Fortunately, furnaces are designed to last 15 to 30 years when maintained well, and you can implement a few fixes during those years to hold onto your system as long as possible.

But knowing when to spring for a whole new furnace and when you can get away (and save yourself some cash) by going the repair route can be tricky. Luckily, a few considerations can help you make an informed decision.

What’s the Problem with Your Furnace?

There’s no denying that the cost to install a new furnace isn’t cheap. On average, you should expect to pay $5,500 for a new device. That’s why taking a moment to see if you should repair or replace your furnace is important, even if yours goes down during the cold winter months.

The most common furnace issues that may require repair or replacement include:

  • Blown motor

  • Broken thermostat

  • Uneven heating or cooling

  • Clogged or dirty filters

  • Cracked heat exchanger

  • Overcycling

  • Switch malfunctions

While many of these issues can be solved with a simple repair or some quick maintenance, some situations might necessitate total replacement, especially if it’s just one of many furnace issues. Knowing when and whom to call when your furnace goes out is important, even if it means tossing on an extra sweatshirt for a couple of hours while you await help. There are, however, some circumstances that merit emergency action and immediate furnace replacement.

Reasons to Replace Your Furnace

A repairman working on a furnace
RichLegg / E+ via Getty Images

Here are six situations where you should spring for a total furnace replacement.

1. Your Furnace Is Emitting Carbon Monoxide

If you suspect your furnace is leaking carbon monoxide, leave your home immediately. Once you’ve evacuated, call the fire department and wait for their directions. Only after that should you start looking into hiring a local pro to install a new furnace.

Carbon monoxide is a toxic, odorless, clear gas that can make you sick or even result in fatalities. The major sign of a carbon monoxide leak is yellow flames in your furnace. An efficient furnace typically emits blue flames.

2. Your Furnace Is Old

Making repairs over the years keeps your HVAC system running properly and efficiently. But even a pristine maintenance schedule won’t keep your furnace going forever.

Consider 15 years a good cutoff when deciding if you’ll replace or repair a furnace. If your furnace is older than that, it’s likely time to replace your unit instead of investing hundreds or thousands of more dollars into repairs.

3. Your Furnace Consistently Makes Loud and Violent Noises

Popping, banging, screeching, rattling, and squealing noises aren’t only loud and distracting—they’re also a sign that your unit could be overheating, which causes metal to expand or grind against objects inside. 

That said, if your unit is still pretty new (less than 10 years old) and you hear these noises, dirt could be an issue. A local furnace repair technician can clean your system and replace filters to address the problem.

4. Repair Costs Are 30% or More What Replacement Would Cost

At a certain point, you may need to cut your losses and just opt for a replacement. Certain repairs (especially beyond the 10- to 15-year mark) aren’t worth pouring money into (unless, of course, buying a new furnace doesn’t fit your budget at the moment).

The cost to replace a blown furnace motor, for example, could be up to $800. Use roughly 30%, or around $1,500 to $2,000 in repairs, as a benchmark for determining whether you should repair or replace your device. Ask local vendors for a quote to find a deal that works for you.

5. Your Furnace Isn’t Warming or Cooling Your Home Evenly

One frustrating outcome of a poorly functioning furnace is uneven heating and cooling. Some rooms might be sweltering, while others are frozen. (Ugh!) 

If this is a persistent problem, it may be time to replace your unit. However, be sure to read the reasons to repair your furnace below if this is your device’s only issue. Sometimes, uneven heating or cooling could have to do with other (more affordable to repair) components of your HVAC system.

6. Your Energy Bills Are Through the Roof

An older or less-efficient furnace may cause your heating or cooling costs to creep up by tens or even hundreds of dollars. This cost can be justifiable for a season or two, especially if your device is pretty new.

However, a sudden spike of several hundred or even thousand dollars per year should give you a reason to consider replacing it.

Reasons to Repair Your Furnace

On the other hand, here are some scenarios where repairing your furnace makes more sense than replacing the entire unit.

1. You’re Planning to Sell Your Home Soon

Are you thinking about selling? In terms of sunken costs, it may make sense to simply preserve your furnace if it still has life in it. Sinking a couple of hundred dollars into your HVAC system as a stopgap solution—hopefully, one that buys it another two or three years of life—might save you thousands instead of buying a new furnace.

2. Your Energy Bills are Going Up

Slight increases to your energy bill don’t always justify or necessitate a furnace replacement. Be sure to read through your maintenance guide and carry out its suggestions, such as replacing the filter on a regular basis. This action is one of the simplest and best furnace maintenance tips you can follow (for all home appliances, really).

3. Your Thermostat Is Broken

A broken thermostat may be the reason your home won’t heat or cool. It’s quite common, and if it’s indeed broken or the battery is dead, there’s probably nothing wrong with the furnace itself.

Some more good news: thermostat repair, one of the most common furnace repairs, may cost you as little as $20 to fix.

4. The Excess Noise Is a Ductwork Issue, Not the Furnace

Your furnace, heat exchange system, vents, and ductwork all make up your home’s HVAC system. Sometimes, banging, screeching, or other loud noises have to do with loose or damaged ductwork instead of your furnace.

Purchasing a vent insulation cover (between $1 and $2 per square foot) is an affordable solution that might solve the problem. Having a professional inspect your vents and ductworks and make any adjustments is also a solid plan B option instead of replacement.

Furnace: Repair or Replace?

A house high efficiency furnace
Marvin Samuel Tolentino Pineda / iStock via Getty Images

So, should you replace or repair your furnace?

Replacing your furnace makes sense when repairs exceed $2,000, you have an old device, energy bills are through the roof, or it’s making loud, scary noises constantly. If you even slightly suspect carbon monoxide is emitting out of your device, evacuate your home immediately and worry about this furnace repair versus replace debate later.

On the other hand, repairing your furnace is probably the better option when minor repairs, such as ductwork tightening, noise reduction, or a broken thermostat, are the culprit.

Need professional help with your project?
Get quotes from top-rated pros.