8 Signs It Might Be Time to Replace Your Old Furnace

1. Your Furnace Keeps Breaking Down

After the first furnace repair, you might think it’s no big deal. Every piece of machinery breaks down once in a while.

If there’s a second breakdown soon after, the price of hanging on to a failing furnace system increases.

You can always choose the repair route instead of a replacement. Then you’re faced with the dilemma: How long do you hang on? Say it needs a $750 repair, and you pay it. Then something else fails. You’re now at a point where you’ve invested almost a grand into your current furnace, so the thinking might be that you should hang onto it to get your money’s worth from the repairs.

It’s a conundrum. You have to weigh reliability issues, the cost of repairs, and the cost of a new furnace. Sooner or later, the repair bills won’t be worth it anymore.

Read more: Cost of Waiting to Repair or Replace HVAC Equipment

2. Your Furnace Is More Than 15 Years Old

Will your aging furnace last another season? This anxiety becomes acute during the first cold snap in November when the furnace is tested for the first time. Is it solid enough to provide heat all winter?

We are often asked how long your furnace might last. Our stock answer is 15-20 years. But it depends on how well it was installed and the quality and frequency of maintenance.

We’ve replaced 10-year-old furnaces, and also ones 30 years old and more. We can diagnose technical issues, but we can’t even guess how long a particular furnace will last - not even after a thorough inspection.

This is not much help, we know.

The best we can do is suggest new models. And we can point out that having a new furnace is a security blanket for the next 10-15 years.

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3. You Have a Cracked Heat Exchanger

This is especially a concern if your warranty has expired. If the furnace has a crack in the heat exchanger, your home isn’t safe.

Heat exchangers are made of metal. Metal expands and contracts. Over time, it will wear out and crack.

A properly tuned natural gas combustion furnace doesn’t produce much carbon monoxide because it will have the correct gas/air mixture. But when that mixture is off, it could start producing a lot of carbon monoxide. A crack in the heat exchanger can cause that.

We’ve been in homes where there is a sickly, sweet smell of incomplete combustion. If the crack worsens - and it will over time - so will the indoor air quality. Carbon monoxide is an odorless, colorless gas that can cause nausea and dizziness. Overexposure to this is deadly.

Replacing a heat exchanger costs around $3,000 and up if the warranty doesn’t cover it. That’s a lot to put into an aged furnace.

4. You Already Need to Replace Your Air Conditioner

Three air conditioning upgrades may require you to replace both your AC and furnace. Check with your HVAC salesperson if you are going to invest in the following:

●        A communicating air conditioner

●        A variable-capacity air conditioner

●        A two-stage air conditioner

A communicating air conditioner uses sophisticated learning technology to customize cooling to your needs and lifestyle. The units “talk” to each other and synchronize their settings.

To truly benefit from a communicating air conditioner, you should have a fully communicating HVAC system. This includes a communicating thermostat and a communicating furnace

When you upgrade your air conditioner, the blower motor in your furnace must be able to support the new air conditioner’s cooling output. Otherwise, your upgraded AC may not work to its full capacity. It may not even work at all, and a warranty won’t cover it.

And speaking of warranties, if you replace both units at the same time, you’ll sync your warranties. It will help you remember whether your existing system is covered if something fails.

You need to understand your options and how they relate to price. If you have a variable-speed air conditioner and aren’t prepared to replace it as well, you’ll need a compatible furnace, which limits your options.  Conversely, if you’re looking to upgrade your HVAC system to variable speed, but your furnace can function only as a single-stage, you’re either sacrificing energy efficiency or won’t be able to upgrade to the variable speed unless you replace the entire system.

5. You're Ready for a More Energy Efficient Furnace

A typical new furnace has an Annual Fuel Utilization Efficiency (AFUE) of 80%, which is called standard efficiency. Essentially, it means that out of every dollar of energy you put into the furnace, it returns 80 cents of heat. The other 20% is waste and is exhausted.

As the parts wear and tear, that AFUE will decrease.

And what’s the AFUE of a high-efficiency furnace? One furnace from Carrier is rated at 98½ AFUE. Switching to that from an old, standard-efficiency furnace will save a homeowner at least 16 cents on the dollar. You will see an immediate benefit on your heating cost.

As an added bonus, it will reduce your carbon footprint. The new furnace will create less exhaust, which contains (among other gasses) carbon dioxide. Less waste means less greenhouse gas.

6. Your Heating Bill Is Creeping Up

This might be difficult to track. After all, it doesn’t take into account how harsh the winters are, temperature fluctuations, how the thermostat is set from month to month, and any improvements to the house (such as added insulation or replacing single-pane windows with an upgrade).

But if circumstances are roughly the same, you can discern a furnace that is working harder and harder. It will take longer to heat the home.

And, as we mentioned before, you’ll see an instant reduction in your energy bill when you switch to a new furnace, no matter what the AFUE rating.

7. You’re Waiting Until Your Furnace Fails

Not waiting until the last moment can pay dividends.

Guess when the busiest time of winter is for heating and cooling companies? Yep. When the temperature drops way down is when the majority of our customers call us to complain about their underperforming furnaces.

The same is true across Central Ohio, and that creates a backlog of service requests. We strive to fix broken furnaces as quickly as possible, but we can deliver portable heaters as bandages to customers during crunch time.

In the meantime, you’re stuck with a broken furnace. This is when waiting too long to make a decision to replace your aged HVAC unit is at its worst. You’ll be in a panic to buy something - anything - that provides heat. Forget shopping around for the best model or HVAC company. You’ll settle for whoever can get a working furnace in place the quickest.

That can be a recipe for disaster. The company that installs your furnace, and the practices they have in place, can literally make the difference between a furnace that lasts 20 years or only 10. It can also affect your comfort level and energy bill.

8. Your Old Furnace Doesn’t Keep You Comfortable

This is probably due to poor installation or improper sizing.

This condition may be the toughest to discern because you’ll get used to your current system. Ask yourself: Does your furnace do a poor job of making every room in the house warm, or does it leave hot and cold spots?

Do the upstairs bedrooms seem fine while the ground floors make you feel cold, no matter what the thermostat is set to?

If you compare fuel bills with your neighbor, does yours seem high? Does your furnace turn on and off more than it should? And is it getting worse?

There might be one of two things at play. One: Your furnace may have been installed poorly. We always say that the most important day in a furnace’s life is the day it’s installed. A poorly installed furnace might work. It may even provide adequate heat. But you’ll never know how comfortable you might have been had the job been done right.

The second issue is that it may have been improperly sized. This happens far more often than it should.

A furnace that is too big will do something called “short cycling.” It will start up, satisfy the thermostat, then shut off before the warm air has a chance to fully mix with the unconditioned air. That’s what leaves warm and cool spots in your home. (It’s also hard on the equipment and can shorten its lifespan.)

If your furnace is too small, it will struggle to satisfy the set temperature. On the coldest days, it will run and run. The fuel bill will rise, and you’ll never get as warm as you would like.

A new furnace - sized and installed correctly - can make a world of difference in your comfort.

The exact price of your new furnace system is something you’ll be able to get only with estimates from HVAC contractors.