A furnace is almost always a background player in your home, keeping you warm in the cold winter months. It regularly won't be noticed until something breaks down. 

One root cause could be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to learn the symptoms 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 inside your furnace to the air that circulates throughout the air ducts. It usually handles this using coils or tubes that heat the air while functioning as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it shouldn't come as a surprise that a cracked heat exchanger can be hazardous. A damaged heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to circulate through your home. 

For obvious reasons, never turn on your heating if you believe you're dealing with a cracked heat exchanger, as letting it run could make your entire household ill. Reach out to an HVAC professional immediately if you think your heater has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger can cause your furnace to shut off. 
  • Odd Smells: If the air leaving your furnace has a powerful chemical scent, it might be a sign gasses are slipping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you recognize health problems: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm could go off or family members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an alarm goes off or you feel unusually tired, exit the home immediately and then call for help. 
  • Soot: If you notice black sooty accumulating on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Mobile right away so they can take a look at your system and, if necessary, start a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are generally covered by 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 still may significantly shrink 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 work the best when they operate efficiently. Contacting a certified professional to examine your furnace for old parts, dirty filters and other likely problems can keep you from getting a big bill later on.  

It’s also helpful to take a look at 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 a part of the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work more vigorously to accomplish its job. And the harder your furnace has to work, the more wear and tear parts like the heat exchanger will endure.