A furnace is usually a background player at home, ensuring you're warm in the cold winter months. It often won't be noticed until something breaks down. 

One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s worthwhile to familiarize yourself with the symptoms of a cracked heat exchanger and what you can do if you are worried that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that circulates through the ventilation. It typically does this through coils or tubes that warm the air while functioning as a barrier to keep gas produced in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Because of its central role, it isn't surprising that a cracked heat exchanger can be very dangerous. Cracks in the heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home. 

For obvious reasons, don't ever use your furnace if you believe there's a crack in the heat exchanger, as doing so could make the whole household sick. Call an HVAC professional immediately if you are worried your heater has a cracked heat exchanger that needs repair. 

Four Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A crack in your heat exchanger could cause your furnace to turn off. 
  • Strange Smells: If the air escaping your furnace has a strong chemical smell, it might be an indicator that gasses are leaking through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm initiates or you feel health problems: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm should go off or family members could struggle with signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unwell, exit the home immediately and then call for help. 
  • Soot: If you notice black sooty accumulating near the exterior of your furnace, it’s an indication something could be seriously wrong.

What You Can Do if the Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a professional with extensive experience in furnace installation Holbrook as soon as possible so they can inspect your system and, if required, start a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates often hover around $1,000 to $3,000. 

However, the good news is that heat exchangers are regularly covered by the warranty. It's a good idea to review the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it can significantly lower your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to avoid problems in your furnace overall is through regular furnace maintenance. Furnaces work the best when they run efficiently. Hiring a certified professional to check your furnace for broken-down parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.  

It’s also beneficial to review 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 pulling air through a clogged filter makes the entire furnace work longer to accomplish its job. And the harder your furnace needs to run, the more strain parts like the heat exchanger will experience.