A furnace is usually a background player in your home, helping keep you warm during the cold winter months. It regularly isn't noticed until something breaks down. 

One source might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to know the signs of a cracked heat exchanger and what you should do if you suspect 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 flows inside the ventilation. It generally accomplishes this with coils or tubes that heat up the air while serving as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its key role, it isn't surprising that a broken heat exchanger can be hazardous. Cracks in the heat exchanger can permit dangerous gasses – such as carbon monoxide, which can be lethal – to be distributed through your home. 

For obvious reasons, don't ever use your furnace if you believe it has a cracked heat exchanger, as this could make the whole family ill. Call an HVAC professional right away if you believe your heater has a cracked heat exchanger that needs to be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger could cause your furnace to switch off. 
  • Odd Smells: If the air coming out of your furnace has a strong chemical odor, it might be a sign gasses are seeping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm could go off or family members might experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If an alarm goes off or you feel sick, get out of the home as soon as you can and then call for help. 
  • Soot: If you notice black sooty buildup near the exterior of your furnace, it’s more evidence something might be seriously wrong.

What You Can Do if a Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, call a pro experienced in furnace installation Port St. Lucie as soon as possible so they can inspect your system and, if necessary, perform a furnace heat exchanger replacement. Costs will vary 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. You’ll want to review the warranty paperwork on your furnace, as while the warranty may not cover the entire cost of repairs, it can significantly lower your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the most convenient ways to minimize the risk of problems in your furnace overall is with routine furnace maintenance. Furnaces work the best when they work efficiently. Contacting a trained professional to inspect your furnace for old parts, clogged filters and other likely problems can help you avoid getting a big bill later on.  

It’s also a good idea to take a look at your furnace filters every few months – it’s encouraged some filters be swapped out 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 harder to complete its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will sustain.