A furnace is almost always a background player in your home, keeping you warm across the cold winter months. It often isn't 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 know the evidence of a cracked heat exchanger and what to do if you believe that is 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 circulates through the air ducts. It typically does this with coils or tubes that warm the air while serving as a barrier to keep byproducts produced in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its central role, it shouldn't come as a surprise that a damaged heat exchanger can pose a risk. A crack in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to flow across your home. 

For that reason, do NOT turn on your heater if you think there's a crack in the heat exchanger, as doing so could make your entire household ill. Reach out to an HVAC professional right away if you think your furnace has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger can cause your furnace to shut off. 
  • Strange Smells: If the air escaping your furnace has a strong chemical odor, it could be evidence gas is slipping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you notice poisoning symptoms: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm could go off or family members could struggle with signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unwell, exit the home as soon as you can and then call for help. 
  • Soot: If you spot black sooty collecting on the exterior of your furnace, it’s another sign something could be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a professional with extensive experience in furnace installation Auburn right away so they can take a look at your system and, if necessary, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

However, the good news is that heat exchangers are generally protected by the warranty. You should review 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 Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to minimize the risk of problems in your furnace overall is with regular furnace maintenance. Furnaces provide the best possible return on investment when they operate efficiently. Calling a trained professional to inspect 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 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 complete its job. And the harder your furnace needs to run, the more strain pieces like the heat exchanger will experience.