A furnace is almost always a background player for your home, helping keep you warm during the cold winter months. It often isn't noticed until something goes wrong. 

One source may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what to do if you believe that might be 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 moves inside the ventilation. It usually accomplishes this via coils or tubes that warm the air while acting as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its central role, it shouldn't come as a surprise that a damaged heat exchanger can be hazardous. A damaged heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow throughout your home. 

For obvious reasons, never use your heating if you believe it has a cracked heat exchanger, as letting it run could make the entire family sick. Contact an HVAC professional right away if you believe your heater has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A cracked heat exchanger can cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has a strong chemical scent, it might be a sign gas is leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you notice poisoning symptoms: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm could go off or household members might start experiencing signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If an alarm goes off or you feel unwell, exit the home immediately and then call for help. 
  • Soot: If you spot black sooty accumulating 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, hire a professional well versed in furnace installation Port St. Lucie right away so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are generally protected by the warranty. You should check the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it can significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to avoid problems in your furnace overall is with consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Calling a skilled professional to inspect your furnace for old parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.  

It’s also beneficial to inspect 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 more vigorously to accomplish its job. And the harder your furnace needs to run, the more strain parts like the heat exchanger will endure.