A furnace is almost always a background player at home, ensuring you're warm in the cold winter months. It often doesn’t get noticed until something breaks down. 

One root cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the signs of a cracked heat exchanger and what you should do if you are worried that may be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber in your furnace to the air that circulates through the system. It generally handles this with coils or tubes that heat up the air while functioning 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? 

Given its important role, it shouldn't come as a surprise that a damaged heat exchanger can be very dangerous. A crack in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to flow throughout your home. 

For that reason, don't ever use your heater if you believe it has a cracked heat exchanger, as letting it run could make your entire household ill. Contact an HVAC professional right away if you think your heater has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger may cause your furnace to shut off. 
  • Strange Smells: If the air coming out of your furnace has an intense chemical smell, it may be a sign gas is slipping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm initiates or you notice health problems: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm could go off or family members may struggle with signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unwell, get out of the home immediately and then call for help. 
  • Soot: If you spot black sooty collecting on the exterior of your furnace, it’s more evidence something could be seriously wrong.

What to Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a pro with extensive experience in furnace installation Tucson and Phoenix right away so they can take a look at your system and, if required, handle a furnace heat exchanger replacement. Costs often 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’ll want to check the warranty paperwork on your furnace, as while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to minimize the risk of problems in your furnace overall is with routine furnace maintenance. Furnaces work the best when they run efficiently. Hiring a trained professional to examine your furnace for worn-out parts, clogged filters and other likely 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 replaced 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 complete its job. And the harder your furnace has to work, the more deterioration parts like the heat exchanger will sustain.