A furnace is usually a background player in your home, keeping you warm in the cold winter months. It frequently won't be noticed until something goes wrong. 

One root cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what you should do if you suspect that might 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 circulates throughout the ventilation. It typically handles this via coils or tubes that warm the air while functioning as a barrier to keep byproducts created in the combustion chamber, called flue gasses, from getting 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 be very dangerous. Cracks in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For this reason, don't ever turn on your heater if you think there's a crack in the heat exchanger, as doing so could make your entire family sick. Call an HVAC professional as soon as possible if you think your furnace has a cracked heat exchanger that should be repaired. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger may cause your furnace to shut off. 
  • Odd Smells: If the air escaping your furnace has an intense chemical scent, it may be evidence gasses are seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm goes off or you feel health problems: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm may go off or family members may experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unwell, exit the home right away and then call for help. 
  • Soot: If you see black sooty buildup 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 believe your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Weatherford right away so they can inspect your system and, if necessary, handle a furnace heat exchanger replacement. Costs will differ 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 covered by the warranty. It's a good idea to check the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to avoid problems in your furnace overall is with regular furnace maintenance. Furnaces offer the most benefits when they run efficiently. Contacting a certified professional to examine your furnace for broken-down parts, clogged filters and other likely problems can keep you from getting a big bill later on.  

It’s also a good idea to inspect your furnace filters every few months – it’s ideal some filters be changed 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 drawing air through a clogged filter makes your entire furnace work more vigorously to accomplish its job. And the harder your furnace needs to run, the more strain parts like the heat exchanger will sustain.