A furnace is often a background player in your home, helping keep you warm during the cold winter months. It often isn't noticed until something breaks down. 

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

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber of your furnace to the air that moves through the air ducts. It typically accomplishes this via coils or tubes that heat the air while acting as a barrier to keep gas formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its key role, it’s no surprise that a broken heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow across your home. 

For obvious reasons, don't ever run your furnace if you suspect you're dealing with a cracked heat exchanger, as doing so could make your entire household ill. Contact an HVAC professional immediately if you believe your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger may cause your furnace to switch off. 
  • Strange Smells: If the air escaping your furnace has a strong chemical scent, it might be a sign gas is slipping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm should go off or family members may struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel unwell, exit the home right away and then call for help. 
  • Soot: If you spot black sooty collecting near the exterior of your furnace, it’s another sign something might be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a professional well versed in furnace installation Weatherford as soon as possible so they can inspect your system and, if required, perform a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally protected by the warranty. It's a good idea to check the warranty paperwork on your furnace, because 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 prevent a problem in your furnace overall is via regular furnace maintenance. Furnaces work the best when they run efficiently. Contacting a trained professional to examine your furnace for broken-down parts, clogs in the air filters and other potential problems can keep you from getting a big bill later on.  

It’s also a good idea to inspect your furnace filters every few months – it’s recommended 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 drawing air through a clogged filter makes your entire furnace work longer to accomplish its job. And the harder your furnace needs to run, the more wear and tear parts like the heat exchanger will endure.