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

One root cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to learn the symptoms of a cracked heat exchanger and what to do if you believe that might 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 circulates throughout the system. It usually does this via coils or tubes that heat the air while functioning as a barrier to keep gas produced in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its central role, it isn't surprising that a broken heat exchanger can pose a risk. A crack in the heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For obvious reasons, do NOT use your heating if you believe there's a crack in the heat exchanger, as letting it run could make the whole family sick. Call an HVAC professional right away if you think your furnace has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger may cause your furnace to turn off. 
  • Odd Smells: If the air escaping your furnace has a strong chemical smell, it may be an indicator that gasses are slipping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you recognize health problems: If a cracked heat exchanger is emitting carbon monoxide in your home, your carbon monoxide alarm may go off or household members could struggle with signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel unwell, get out of the home immediately and then call for help. 
  • Soot: If you notice black sooty collecting around the exterior of your furnace, it’s another sign something might be seriously wrong.

What You Can Do if the Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional well versed in furnace installation Swanton right away so they can examine your system and, if necessary, perform a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are often protected by the warranty. You’ll want to confirm the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it could significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is via consistent furnace maintenance. Furnaces offer the most benefits when they run efficiently. Contacting a skilled professional to inspect your furnace for broken-down parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.  

It’s also helpful to take a look at your furnace filters every few months – it’s encouraged 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 drawing air through a clogged filter makes the entire furnace work harder to accomplish its job. And the harder your furnace works, the more deterioration components like the heat exchanger will experience.