A furnace is almost always a background player for your home, helping keep you warm during the cold winter months. It regularly doesn’t get noticed until something breaks down. 

One source could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what to do if you believe that may 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 moves through the system. It typically handles this through coils or tubes that warm the air while acting as a barrier to keep gas produced in the combustion chamber, called flue gasses, from getting out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

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

For obvious reasons, never run your heating 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 are worried your heating has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger could cause your furnace to switch off. 
  • Odd Smells: If the air leaving your furnace has a powerful chemical odor, it could be a sign gas is slipping 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 symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm may go off or household members could experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel sick, get out of the home right away and then call for help. 
  • Soot: If you notice black sooty accumulating on the exterior of your furnace, it’s another sign 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, contact a pro experienced in furnace installation Los Angeles as soon as possible so they can inspect your system and, if necessary, handle a furnace heat exchanger replacement. Costs should differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

However, the good news is that heat exchangers are often protected by the warranty. You should review the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it could significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the best ways to prevent a problem in your furnace overall is through regular furnace maintenance. Furnaces work the best when they run efficiently. Calling a trained professional to examine your furnace for old parts, clogs in the air filters and other likely problems can keep you from getting a big bill later on.  

It’s also helpful to review your furnace filters every few months – it’s recommended 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 your entire furnace work longer to complete its job. And the harder your furnace works, the more strain pieces like the heat exchanger will sustain.