A furnace is usually a background player in your home, keeping you warm during the cold winter months. It regularly doesn’t get noticed until something goes wrong. 

One source may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to familiarize yourself with the evidence of a cracked heat exchanger and what you should do if you suspect that is the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger helps move heat from the combustion chamber inside your furnace to the air that flows inside the ventilation. It usually handles this using coils or tubes that warm the air while functioning as a barrier to keep gas formed in the combustion chamber, called flue gasses, from leaking out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Thanks to its important role, it shouldn't come as a surprise that a broken heat exchanger can pose a risk. A crack in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to circulate across your home. 

For this reason, don't ever run your furnace if you think you're dealing with a cracked heat exchanger, as this could make the entire household sick. Contact an HVAC professional right away if you are worried your heater has a cracked heat exchanger that needs repair. 

Four Warning Signs of a Cracked Heat Exchanger: 

  • Furnace switches off: Cracks in the heat exchanger can cause your furnace to shut off. 
  • Odd Smells: If the air leaving your furnace has an intense chemical smell, it could be a sign gas is seeping through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a common warning sign. 
  • Carbon monoxide alarm is triggered or you feel symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide inside your home, your carbon monoxide alarm may go off or family members might start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unusually tired, leave the home right away and then call for help. 
  • Soot: If you find black sooty buildup on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a pro experienced in furnace installation Lawrence right away so they can take a look at your system and, if required, start a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000. 

However, the good news is that heat exchangers are generally 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 still may significantly shrink your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the best ways to avoid problems in your furnace overall is through routine furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Hiring a skilled professional to inspect your furnace for worn-out parts, clogged filters and other common problems can help you avoid getting a big bill later on.  

It’s also beneficial to inspect your furnace filters every few months – it’s recommended some filters be replaced 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 drawing air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace has to work, the more strain components like the heat exchanger will endure.