A furnace is usually a background player at home, helping keep you warm in the cold winter months. It regularly isn't noticed until a malfunction appears. 

One source may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to familiarize yourself with the symptoms of a cracked heat exchanger and what you should do if you are worried that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber in your furnace to the air that flows through the air ducts. It generally handles this via coils or tubes that heat the air while functioning as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its key role, it’s no surprise that a broken heat exchanger can be hazardous. A crack in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For obvious reasons, do NOT run your furnace if you believe it has a cracked heat exchanger, as doing so could make the entire family ill. Reach out to an HVAC professional right away if you believe your heating has a cracked heat exchanger that should be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger may cause your furnace to turn off. 
  • Unusual Smells: If the air coming out of your furnace has an intense chemical smell, it could be a sign gasses are leaking through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you notice poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm could go off or household members could struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel sick, leave the home immediately and then call for help. 
  • Soot: If you spot black sooty collecting around the exterior of your furnace, it’s another sign something might be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Rapid City right away so they can examine your system and, if required, perform a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are generally included in the warranty. You should confirm the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it can significantly reduce 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 operate efficiently. Hiring a certified 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 beneficial to take a look at your furnace filters every few months – it’s recommended some filters be replaced every 90 days or sooner if they are dirty or grimy. While the filters aren't connected to the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work more vigorously to accomplish its job. And the harder your furnace has to work, the more wear and tear parts like the heat exchanger will sustain.