A furnace is usually a background player at home, ensuring you're warm in the cold winter months. It frequently isn't noticed until a malfunction appears. 

One source might be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to learn the symptoms 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 helps move heat from the combustion chamber of your furnace to the air that circulates through the ventilation. It typically handles this via coils or tubes that heat the air while functioning as a barrier to keep byproducts created 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 isn't surprising that a damaged heat exchanger can be hazardous. Cracks in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to circulate through your home. 

For obvious reasons, never use your heater if you believe you're dealing with a cracked heat exchanger, as doing so could make the whole family sick. Contact an HVAC professional right away if you think your heater has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: A cracked heat exchanger may cause your furnace to switch off. 
  • Strange Smells: If the air escaping your furnace has an intense chemical smell, it could be a sign gasses are slipping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a major warning sign. 
  • Carbon monoxide alarm initiates or you recognize symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide in your home, your carbon monoxide alarm may go off or household 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, get out of the home immediately and then call for help. 
  • Soot: If you notice black sooty buildup near the exterior of your furnace, it’s an indication something may be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, call a professional experienced in furnace installation Norton as soon as possible so they can inspect your system and, if required, perform 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 included in the warranty. It's a good idea to review the warranty paperwork on your furnace, as while the warranty may not cover the entire cost of repairs, it still may significantly lower 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 via regular furnace maintenance. Furnaces work the best when they run efficiently. Hiring a trained professional to examine your furnace for old parts, dirty 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 dragging air through a clogged filter makes the entire furnace work longer to do its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will endure.