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

One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the signs of a cracked heat exchanger and what to do if you believe 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 throughout the air ducts. It generally handles this via coils or tubes that heat the air while functioning as a barrier to keep byproducts formed 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 cracked heat exchanger can be hazardous. A crack in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home. 

For that reason, do NOT turn on your heater if you think it has a cracked heat exchanger, as doing so could make your entire household sick. Contact an HVAC professional right away if you think your heating has a cracked heat exchanger that needs to be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger may cause your furnace to turn off. 
  • Odd Smells: If the air leaving your furnace has an intense chemical odor, it could be a sign gas is leaking through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or family members could struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unusually tired, get out of the home right away and then call for help. 
  • Soot: If you see black sooty accumulating around the exterior of your furnace, it’s another sign something could be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Temple/Belton right away so they can inspect your system and, if required, start a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates often hover around $1,000 to $3,000. 

Estimates aside, 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, since while the warranty might not cover the entire cost of repairs, it can significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is with consistent furnace maintenance. Furnaces work the best when they operate efficiently. Hiring a trained professional to check your furnace for worn-out parts, dirty filters and other likely problems can help you avoid getting a big bill later on.  

It’s also beneficial to review your furnace filters every few months – it’s ideal some filters be replaced every 90 days or sooner if they are dirty or grimy. While the filters are not part of the heat exchanger itself, the strain of drawing air through a clogged filter makes your entire furnace work more vigorously to accomplish its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will sustain.