A furnace is often a background player in your home, keeping you warm during the cold winter months. It frequently doesn’t get noticed until something goes wrong. 

One root cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to learn the symptoms 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 of your furnace to the air that circulates inside the system. It usually handles this using coils or tubes that warm the air while serving as a barrier to keep gas produced in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its central role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. Cracks in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home. 

For this reason, do NOT run your furnace if you think it has a cracked heat exchanger, as doing so could make the entire household sick. Call an HVAC professional right away if you are worried your heating has a cracked heat exchanger that needs to be repaired. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace turns off: A crack in your heat exchanger could cause your furnace to turn off. 
  • Strange Smells: If the air leaving your furnace has a strong chemical odor, it might be evidence gasses are seeping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm could go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unwell, get out of the home as soon as you can and then call for help. 
  • Soot: If you find black sooty collecting around the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Can Do if Your Furnace Heat Exchanger is Cracked 

If you worry your furnace has a cracked heat exchanger, contact a professional with extensive experience in furnace installation Pocatello right away so they can examine your system and, if needed, perform a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally protected by the warranty. You’ll want to check the warranty paperwork on your furnace, because while the warranty may not cover the entire cost of repairs, it still may 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 consistent furnace maintenance. Furnaces work the best when they operate efficiently. Hiring a skilled professional to inspect your furnace for old parts, clogged filters and other potential problems can keep you from getting a big bill later on.  

It’s also helpful to inspect your furnace filters every few months – it’s ideal 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 pulling air through a clogged filter makes your entire furnace work longer to accomplish its job. And the harder your furnace works, the more strain pieces like the heat exchanger will sustain.