A furnace is almost always a background player for your home, helping keep you warm in the cold winter months. It frequently doesn’t get noticed until a malfunction appears. 

One cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to familiarize yourself with 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 transfers heat from the combustion chamber of your furnace to the air that flows inside the air ducts. It usually does this via coils or tubes that warm the air while acting 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 key role, it’s no surprise that a damaged heat exchanger can pose a risk. Cracks in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to be distributed through your home. 

For this reason, don't ever use your heater if you suspect there's a crack in the heat exchanger, as letting it run could make the whole family ill. Reach out to an HVAC professional as soon as possible if you believe your furnace has a cracked heat exchanger that needs repair. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger can cause your furnace to switch off. 
  • Unusual Smells: If the air leaving your furnace has a powerful chemical odor, it may be an indicator that gas is seeping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you notice health problems: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm should go off or family members may experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unwell, leave the home as soon as you can and then call for help. 
  • Soot: If you see black sooty accumulating near 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 worry your furnace has a cracked heat exchanger, call a pro well versed in furnace installation Oxford right away so they can examine your system and, if needed, perform 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 regularly included in the warranty. You should review the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it still may significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

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

It’s also beneficial to review your furnace filters every few months – it’s encouraged some filters be changed 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 more vigorously to do its job. And the harder your furnace works, the more deterioration parts like the heat exchanger will endure.