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

One source may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to familiarize yourself with the evidence of a cracked heat exchanger and what you should do if you believe that may 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 throughout the air ducts. It generally accomplishes this using coils or tubes that warm the air while functioning as a barrier to keep gas produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its key role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to circulate throughout your home. 

For this reason, do NOT use your heater if you think there's a crack in the heat exchanger, as letting it run could make the whole family ill. Contact an HVAC professional as soon as possible if you think your heating has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger can cause your furnace to turn off. 
  • Odd Smells: If the air coming out of your furnace has an intense chemical scent, it might be evidence gas is slipping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you notice health problems: If a cracked heat exchanger is emitting carbon monoxide in your home, your carbon monoxide alarm could go off or family members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an alarm goes off or you feel sick, get out of the home right away and then call for help. 
  • Soot: If you spot black sooty accumulating near the exterior of your furnace, it’s an indication something may be seriously wrong.

What to Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Tucker right away so they can take a look at your system and, if needed, perform a furnace heat exchanger replacement. Costs often vary 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 check the warranty paperwork on your furnace, as while the warranty might not cover the entire cost of repairs, it still may significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is with regular furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a trained 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 review your furnace filters every few months – it’s ideal some filters be changed every 90 days or sooner if they are dirty or grimy. While the filters aren't a part of the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work longer to accomplish its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will endure.