A furnace is often a background player in your home, helping keep you warm during the cold winter months. It regularly isn't noticed until something breaks down. 

One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to know the evidence of a cracked heat exchanger and what you should do if you suspect that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber of your furnace to the air that circulates inside the system. It typically accomplishes this with coils or tubes that heat up the air while acting as a barrier to keep gas created in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it’s no surprise that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow across your home. 

For this reason, do NOT turn on your heating if you suspect it has a cracked heat exchanger, as doing so could make your entire household ill. Contact an HVAC professional as soon as possible if you are worried your heater has a cracked heat exchanger that needs to be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger can cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has a strong chemical smell, it might be an indicator that gasses are leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you feel poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm may go off or family members might struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel sick, exit the home immediately and then call for help. 
  • Soot: If you find black sooty buildup near the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Carpentersville right away so they can examine your system and, if necessary, perform a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are often covered by the warranty. It's a good idea to review the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it still may significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to minimize the risk of problems in your furnace overall is via consistent furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a skilled professional to check your furnace for worn-out parts, dirty filters and other potential problems can help you avoid getting a big bill later on.  

It’s also helpful to take a look at your furnace filters every few months – it’s recommended 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 drawing air through a clogged filter makes the entire furnace work harder to do its job. And the harder your furnace works, the more strain parts like the heat exchanger will sustain.