A furnace is almost always a background player in your home, keeping you warm in the cold winter months. It often won't be noticed until a malfunction appears. 

One root cause could be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to learn the symptoms of a cracked heat exchanger and what you can do if you believe that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber of your furnace to the air that moves through the air ducts. It typically accomplishes this through coils or tubes that heat the air while functioning as a barrier to keep the gasses created in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its central role, it isn't surprising that a cracked heat exchanger can pose a risk. Cracks in the heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to be distributed throughout your home. 

For this reason, never run your heater if you believe it has a cracked heat exchanger, as letting it run could make your entire household sick. Reach out to an HVAC professional as soon as possible if you are worried your heating has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger could cause your furnace to turn off. 
  • Odd Smells: If the air escaping your furnace has a powerful chemical scent, it might be a sign gas is seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or household members may experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel unusually tired, leave the home right away and then call for help. 
  • Soot: If you find black sooty accumulating on the exterior of your furnace, it’s an indication something might be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Omaha right away so they can take a look at your system and, if necessary, start a furnace heat exchanger replacement. Costs should differ depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are often included in the warranty. It's a good idea to check the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it could significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to avoid problems in your furnace overall is with consistent furnace maintenance. Furnaces work the best when they work efficiently. Contacting a trained professional to check your furnace for worn-out parts, clogs in the air filters and other likely problems can keep you from getting a big bill later on.  

It’s also a good idea to review your furnace filters every few months – it’s encouraged some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters aren't connected to the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work more vigorously to do its job. And the harder your furnace needs to run, the more deterioration pieces like the heat exchanger will endure.