A furnace is usually a background player at home, helping keep you warm in the cold winter months. It frequently isn't noticed until something goes wrong. 

One cause may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what you should 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 of your furnace to the air that circulates throughout the air ducts. It typically accomplishes this using coils or tubes that heat up the air while functioning as a barrier to keep the gasses created in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its key role, it isn't surprising that a cracked heat exchanger can be very dangerous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to flow through your home. 

For obvious reasons, don't ever use your heater if you think there's a crack in the heat exchanger, as doing so could make the whole household sick. Call an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger can cause your furnace to turn off. 
  • Unusual Smells: If the air coming out of your furnace has an intense chemical odor, it could be evidence gas is seeping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm could go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If an alarm goes off or you feel unwell, get out of the home as soon as you can and then call for help. 
  • Soot: If you find black sooty buildup near the exterior of your furnace, it’s more evidence something might 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 Libertyville right away so they can take a look at your system and, if needed, handle a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are regularly protected by the warranty. You should review the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it could significantly shrink your bill.  

How to Prevent 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 consistent furnace maintenance. Furnaces work the best when they operate efficiently. Calling 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 ideal some filters be swapped out 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 dragging air through a clogged filter makes your entire furnace work longer to do its job. And the harder your furnace needs to run, the more strain components like the heat exchanger will sustain.