A furnace is often a background player for your home, helping keep you warm during the cold winter months. It often doesn’t get noticed until something goes wrong. 

One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to familiarize yourself with the signs of a cracked heat exchanger and what to do if you suspect that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber in your furnace to the air that moves inside the system. It generally handles this via coils or tubes that heat up 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? 

Thanks to its important role, it isn't surprising that a cracked heat exchanger can be hazardous. Cracks in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to be distributed throughout your home. 

For this reason, don't ever use your furnace if you believe there's a crack in the heat exchanger, as this could make the whole household sick. Reach out to an HVAC professional immediately if you think your heating has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger can cause your furnace to switch off. 
  • Odd Smells: If the air escaping your furnace has a strong chemical odor, it might be evidence gasses are leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you notice symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm may go off or family members might experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unwell, leave the home right away and then call for help. 
  • Soot: If you spot black sooty accumulating around the exterior of your furnace, it’s an indication something might be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Portland right away so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally included in the warranty. You’ll want to review the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it still may significantly shrink your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to avoid problems in your furnace overall is via consistent furnace maintenance. Furnaces work the best when they run efficiently. Contacting a trained professional to inspect your furnace for worn-out parts, clogs in the air filters and other potential problems can help you avoid getting a big bill later on.  

It’s also beneficial to take a look at your furnace filters every few months – it’s recommended some filters be changed 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 more vigorously to accomplish its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will endure.