A furnace is often 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 source might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to know the evidence of a cracked heat exchanger and what you can do if you suspect that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that flows throughout the system. It generally handles this via coils or tubes that heat the air while serving 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 important role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A damaged heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to circulate throughout your home. 

For obvious reasons, don't ever turn on your furnace if you think it has a cracked heat exchanger, as letting it run could make the whole family sick. Call an HVAC professional right away if you believe your furnace has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger can cause your furnace to shut off. 
  • Strange Smells: If the air leaving your furnace has an intense chemical scent, it might be evidence gasses are leaking through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm should go off or family members might experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unusually tired, get out of the home right away and then call for help. 
  • Soot: If you see black sooty collecting around the exterior of your furnace, it’s another sign something may be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Oxford right away so they can take a look at your system and, if needed, perform a furnace heat exchanger replacement. Costs should differ 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 covered by the warranty. You should review the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it could significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient 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 examine your furnace for old parts, clogs in the air filters and other common problems can help you avoid getting a big bill later on.  

It’s also helpful to review your furnace filters every few months – it’s recommended 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 your entire furnace work more vigorously to do its job. And the harder your furnace works, the more deterioration components like the heat exchanger will endure.