A furnace is almost always a background player for your home, ensuring you're warm during the cold winter months. It regularly won't be noticed until something goes wrong. 

One cause may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s critical to familiarize yourself with the signs of a cracked heat exchanger and what you can do if you are worried that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber inside your furnace to the air that flows inside the system. It usually does this through coils or tubes that heat the air while acting as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its important role, it’s no surprise that a cracked heat exchanger can be hazardous. A damaged heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to be distributed through your home. 

For obvious reasons, never use your furnace if you suspect you're dealing with a cracked heat exchanger, as this could make the whole family ill. Reach out to an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that needs repair. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger can cause your furnace to turn off. 
  • Strange Smells: If the air coming out of your furnace has an intense chemical scent, it might be evidence gasses are seeping 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 relieving carbon monoxide in 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 sleepy. If the alarm goes off or you feel sick, get out of the home immediately and then call for help. 
  • Soot: If you notice black sooty buildup on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a pro well versed in furnace installation Marshfield as soon as possible so they can examine your system and, if needed, handle a furnace heat exchanger replacement. Costs will fluctuate depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are generally covered by the warranty. You should review the warranty paperwork on your furnace, since 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 easiest ways to minimize the risk of problems in your furnace overall is via routine furnace maintenance. Furnaces provide the best possible return on investment when they work efficiently. Calling 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 helpful to take a look at 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 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 has to work, the more deterioration parts like the heat exchanger will sustain.