A furnace is often a background player in your home, ensuring you're warm in the cold winter months. It often isn't noticed until a malfunction appears. 

One cause may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to know the evidence of a cracked heat exchanger and what you should do if you believe that may be 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 flows throughout the air ducts. It generally accomplishes this through coils or tubes that warm the air while acting as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from escaping 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 be hazardous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to flow through your home. 

For that reason, do NOT 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 right away if you think your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger could cause your furnace to turn off. 
  • Unusual Smells: If the air coming out of your furnace has a powerful chemical scent, it may be a sign gas is seeping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm may go off or household members might struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel unwell, leave the home immediately and then call for help. 
  • Soot: If you find black sooty collecting near the exterior of your furnace, it’s more evidence something could 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 pro well versed in furnace installation Columbus right away so they can inspect your system and, if necessary, handle a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

However, the good news is that heat exchangers are regularly protected by the warranty. It's a good idea to confirm the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it can significantly shrink your bill.  

How to Avoid 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 provide the best possible return on investment when they work efficiently. Contacting a certified professional to examine your furnace for worn-out parts, dirty filters and other potential problems can help you avoid getting a big bill later on.  

It’s also a good idea 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 are not part of the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work more vigorously to complete its job. And the harder your furnace has to work, the more strain components like the heat exchanger will sustain.