A furnace is usually a background player in your home, ensuring you're warm across the cold winter months. It frequently won't be noticed until a malfunction appears. 

One cause might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to familiarize yourself with the symptoms of a cracked heat exchanger and what you can do if you suspect that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that circulates through the ventilation. It usually accomplishes this through coils or tubes that heat up the air while serving as a barrier to keep gas formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it’s no surprise that a cracked heat exchanger can be hazardous. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home. 

For this reason, don't ever turn on your furnace if you think you're dealing with a cracked heat exchanger, as this could make the entire household ill. Call an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger could cause your furnace to shut off. 
  • Odd Smells: If the air coming out of your furnace has a powerful chemical smell, it may be evidence gas is leaking through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you recognize poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm should go off or family members could experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel sick, leave the home right away and then call for help. 
  • Soot: If you notice black sooty buildup around the exterior of your furnace, it’s more evidence something might be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Lansing right away so they can inspect your system and, if necessary, perform a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are often protected by the warranty. It's a good idea to confirm the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it can significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the easiest ways to prevent a problem in your furnace overall is with regular furnace maintenance. Furnaces offer the most benefits when they run efficiently. Calling a skilled professional to check your furnace for worn-out parts, clogs in the air filters and other potential problems can help you avoid getting a big bill later on.  

It’s also a good idea to inspect your furnace filters every few months – it’s recommended some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters are not part of the heat exchanger itself, the strain of drawing air through a clogged filter makes your entire furnace work harder to accomplish its job. And the harder your furnace works, the more deterioration parts like the heat exchanger will experience.