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 could be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to familiarize yourself with the signs of a cracked heat exchanger and what you can do if you believe that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber in your furnace to the air that flows inside the system. It usually does this via coils or tubes that heat the air while acting 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 important role, it’s no surprise that a cracked heat exchanger can pose a risk. Cracks in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For obvious reasons, do NOT run your heater if you believe you're dealing with a cracked heat exchanger, as doing so could make the entire household ill. Reach out to an HVAC professional immediately if you think your furnace has a cracked heat exchanger that needs repair. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace shuts off: A cracked heat exchanger may cause your furnace to shut off. 
  • Unusual Smells: If the air leaving your furnace has an intense chemical odor, it may be a sign gas is leaking through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm is triggered or you feel poisoning symptoms: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm may go off or family members might 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, leave the home immediately and then call for help. 
  • Soot: If you spot black sooty collecting around the exterior of your furnace, it’s more evidence something might be seriously wrong.

What You Should Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Narvon as soon as possible so they can inspect your system and, if necessary, handle a furnace heat exchanger replacement. Costs will fluctuate depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

Estimates aside, the good news is that heat exchangers are regularly covered by the warranty. It's a good idea to check the warranty paperwork on your furnace, since while the warranty might not cover the entire cost of repairs, it can significantly reduce 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 routine furnace maintenance. Furnaces offer the most benefits when they run efficiently. Contacting a trained professional to inspect your furnace for worn-out parts, clogged filters and other potential problems can keep you from getting a big bill later on.  

It’s also helpful to take a look at 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 a part of the heat exchanger itself, the strain of dragging air through a clogged filter makes the entire furnace work longer to accomplish its job. And the harder your furnace has to work, the more deterioration parts like the heat exchanger will sustain.