A furnace is usually a background player in your home, ensuring you're warm in the cold winter months. It regularly won't be noticed until something goes wrong. 

One root cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to familiarize yourself with the signs of a cracked heat exchanger and what you can do if you suspect that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber of your furnace to the air that moves throughout the ventilation. It usually handles this with coils or tubes that warm the air while functioning as a barrier to keep gas formed in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its important role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to circulate through your home. 

For this reason, never use your heater if you think it has a cracked heat exchanger, as doing so could make the entire household sick. Call an HVAC professional right away if you believe your heating has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger can cause your furnace to turn off. 
  • Odd Smells: If the air leaving your furnace has a strong chemical smell, it might be a sign gas is leaking through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you recognize poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide inside your home, your carbon monoxide alarm could go off or household members might experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unwell, leave the home immediately and then call for help. 
  • Soot: If you find black sooty accumulating around the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, hire a pro with extensive experience in furnace installation Lincoln right away so they can inspect your system and, if required, handle a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

However, the good news is that heat exchangers are generally protected 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 could significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to prevent a problem in your furnace overall is via regular furnace maintenance. Furnaces work the best when they work efficiently. Calling a certified professional to examine your furnace for worn-out parts, dirty filters and other potential 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 recommended some filters be replaced 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 your entire furnace work more vigorously to complete its job. And the harder your furnace works, the more deterioration components like the heat exchanger will experience.