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

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

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that flows through the air ducts. It generally handles this with coils or tubes that heat the air while serving as a barrier to keep byproducts created in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its important role, it shouldn't come as a surprise 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 flow through your home. 

For obvious reasons, do NOT use your heating if you think there's a crack in the heat exchanger, as doing so could make your entire family ill. Contact an HVAC professional as soon as possible if you are worried your furnace has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger could cause your furnace to turn off. 
  • Odd Smells: If the air coming out of your furnace has a strong chemical odor, it could be a sign gas is slipping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or family members may experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel sick, exit the home immediately and then call for help. 
  • Soot: If you spot black sooty buildup near the exterior of your furnace, it’s another sign something may be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Ames as soon as possible so they can examine your system and, if needed, start a furnace heat exchanger replacement. Costs often fluctuate 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 regularly protected by the warranty. You’ll want to confirm the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it can significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to prevent a problem in your furnace overall is with routine furnace maintenance. Furnaces work the best when they run efficiently. Hiring a trained professional to examine your furnace for worn-out parts, clogged filters and other common problems can help you avoid getting a big bill later on.  

It’s also a good idea to inspect 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 are not part of 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 works, the more wear and tear parts like the heat exchanger will endure.