A furnace is usually a background player at home, ensuring you're warm during the cold winter months. It frequently doesn’t get noticed until something breaks down. 

One source might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to know the evidence of a cracked heat exchanger and what you should do if you are worried that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber in your furnace to the air that circulates through the air ducts. It usually accomplishes this through coils or tubes that heat the air while functioning as a barrier to keep gas produced in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its key role, it isn't surprising that a damaged heat exchanger can be hazardous. Cracks in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home. 

For this reason, do NOT use your furnace if you think there's a crack in the heat exchanger, as doing so could make the entire family sick. Reach out to an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger can cause your furnace to shut off. 
  • Unusual Smells: If the air leaving your furnace has an intense chemical scent, it may be evidence gasses are seeping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide inside your home, your carbon monoxide alarm should go off or household members may struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel sick, leave the home immediately and then call for help. 
  • Soot: If you find black sooty collecting near the exterior of your furnace, it’s another sign something might 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 with extensive experience in furnace installation Greater Richmond right away so they can examine your system and, if needed, perform a furnace heat exchanger replacement. Costs will 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 regularly included in the warranty. You’ll want to review the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the easiest ways to avoid problems in your furnace overall is via consistent furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Contacting a skilled professional to examine your furnace for worn-out parts, dirty filters and other likely 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 encouraged some filters be replaced 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 pulling 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 deterioration pieces like the heat exchanger will experience.