A furnace is often a background player at home, helping keep you warm in the cold winter months. It often doesn’t get noticed until a malfunction appears. 

One source might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to know the signs of a cracked heat exchanger and what to do if you are worried that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that flows inside the system. It usually handles this via coils or tubes that warm the air while acting as a barrier to keep the gasses created 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 isn't surprising that a damaged heat exchanger can be hazardous. A crack in the heat exchanger can allow dangerous gasses – including carbon monoxide, which can be lethal – to circulate through your home. 

For obvious reasons, don't ever run your heating if you suspect there's a crack in the heat exchanger, as letting it run could make your entire family sick. Reach out to an HVAC professional right away if you believe your heater has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace shuts off: A crack in your heat exchanger may cause your furnace to shut off. 
  • Unusual Smells: If the air escaping your furnace has a strong chemical odor, it could be evidence gas is slipping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm goes off or you feel poisoning symptoms: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm could go off or household members could struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel unusually tired, exit the home right away and then call for help. 
  • Soot: If you find black sooty collecting near the exterior of your furnace, it’s an indication something could be seriously wrong.

What to Do if Your Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro with extensive experience in furnace installation Chelan and Wenatchee as soon as possible so they can inspect your system and, if necessary, start a furnace heat exchanger replacement. Costs will vary 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 often covered by the warranty. You’ll want to confirm the warranty paperwork on your furnace, since while the warranty won't always cover the entire cost of repairs, it could significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to minimize the risk of problems in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they run efficiently. Hiring a trained professional to check your furnace for old parts, dirty 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 replaced 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 complete its job. And the harder your furnace has to work, the more wear and tear components like the heat exchanger will endure.