A furnace is usually a background player for your home, keeping you warm during the cold winter months. It frequently doesn’t get 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 worthwhile to learn the symptoms of a cracked heat exchanger and what you can do if you suspect that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber in your furnace to the air that moves inside the system. It usually does this through coils or tubes that heat the air while acting as a barrier to keep byproducts formed 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 isn't surprising that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to be distributed through your home. 

For that reason, never run your heating if you believe it has a cracked heat exchanger, as letting it run could make the whole household sick. Call an HVAC professional immediately if you are worried your heating has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger could cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has an intense chemical smell, it might be a sign gasses are seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you recognize poisoning symptoms: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm should go off or household members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unwell, exit the home immediately and then call for help. 
  • Soot: If you notice black sooty buildup around the exterior of your furnace, it’s an indication something may be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Carson City as soon as possible so they can take a look at your system and, if required, perform 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 regularly protected by the warranty. You should confirm the warranty paperwork on your furnace, as while the warranty might not cover the entire cost of repairs, it can 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 with regular furnace maintenance. Furnaces work the best when they work efficiently. Contacting a trained professional to check 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 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 drawing air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace has to work, the more strain pieces like the heat exchanger will experience.