A furnace is almost always a background player in your home, keeping you warm during the cold winter months. It often doesn’t get noticed until something goes wrong. 

One cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to know the symptoms of a cracked heat exchanger and what you can do if you are worried that is 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 flows through the system. It usually does this through coils or tubes that heat the air while functioning as a barrier to keep byproducts produced in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its important role, it shouldn't come as a surprise that a broken heat exchanger can pose a risk. A crack in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to circulate throughout your home. 

For that reason, don't ever run your heater if you suspect there's a crack in the heat exchanger, as letting it run could make the entire household ill. Reach out to an HVAC professional right away if you believe your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger may cause your furnace to shut off. 
  • Unusual Smells: If the air coming out of your furnace has a strong chemical scent, it may be evidence gas is seeping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you recognize symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide in your home, your carbon monoxide alarm may go off or family members might struggle with signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel unusually tired, leave the home right away and then call for help. 
  • Soot: If you notice black sooty accumulating on the exterior of your furnace, it’s another sign something may be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a pro with extensive experience in furnace installation Mankato area as soon as possible so they can examine your system and, if required, perform a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally included in the warranty. It's a good idea to review the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it still may significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is with consistent furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Contacting a skilled professional to inspect your furnace for old parts, clogs in the air filters and other common problems can keep you from getting a big bill later on.  

It’s also helpful to review your furnace filters every few months – it’s ideal some filters be swapped out 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 dragging air through a clogged filter makes your entire furnace work harder to accomplish its job. And the harder your furnace needs to run, the more wear and tear pieces like the heat exchanger will endure.