A furnace is almost always a background player at home, ensuring you're warm in the cold winter months. It regularly won't be noticed until something breaks down. 

One cause may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to learn the symptoms of a cracked heat exchanger and what you should do if you suspect that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber of your furnace to the air that moves through the ventilation. It usually does this through coils or tubes that warm the air while serving as a barrier to keep gas formed in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

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

For this reason, don't ever turn on your heater if you believe it has a cracked heat exchanger, as this could make the whole family ill. Contact an HVAC professional right away if you think your heating has a cracked heat exchanger that needs repair. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger may cause your furnace to switch off. 
  • Strange Smells: If the air leaving your furnace has a strong chemical odor, it may be a sign gas is seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm initiates or you notice poisoning symptoms: If a cracked heat exchanger is emitting carbon monoxide in your home, your carbon monoxide alarm should go off or household members might experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel sick, exit the home right away and then call for help. 
  • Soot: If you notice black sooty accumulating on 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 worry your furnace has a cracked heat exchanger, hire a pro with extensive experience in furnace installation Rapid City right away so they can examine your system and, if needed, perform a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are often included in the warranty. You should review the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it could significantly reduce 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 through routine furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Hiring 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 helpful to take a look at 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 connected to the heat exchanger itself, the strain of pulling air through a clogged filter makes the entire furnace work more vigorously to complete its job. And the harder your furnace works, the more wear and tear pieces like the heat exchanger will sustain.