A furnace is usually a background player at home, ensuring you're warm across the cold winter months. It frequently doesn’t get noticed until something goes wrong. 

One source could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to know the signs of a cracked heat exchanger and what you should do if you suspect that might be the problem.  

What Is a Heat Exchanger in a Furnace? 

A heat exchanger transfers heat from the combustion chamber inside your furnace to the air that circulates through the air ducts. It generally does this through coils or tubes that warm the air while serving 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 central role, it’s no surprise that a cracked heat exchanger can pose a risk. A damaged heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to circulate across your home. 

For obvious reasons, never use your furnace if you think there's a crack in the heat exchanger, as this could make the entire household ill. Contact an HVAC professional right away if you believe your furnace has a cracked heat exchanger that needs to be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: Cracks in the heat exchanger can cause your furnace to switch off. 
  • Odd Smells: If the air leaving your furnace has an intense chemical smell, it may be a sign gas is seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm is triggered or you recognize poisoning symptoms: 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 tired. If an alarm goes off or you feel sick, exit 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 You Can Do if the Furnace Heat Exchanger is Cracked 

If you believe your furnace has a cracked heat exchanger, hire a professional experienced in furnace installation Troy as soon as possible so they can examine your system and, if necessary, handle a furnace heat exchanger replacement. Costs often vary depending on the situation, but estimates often hover around $1,000 to $3,000. 

Estimates aside, 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, as while the warranty may not cover the entire cost of repairs, it still may significantly reduce your bill.  

How to Avoid a Cracked Heat Exchanger in Your Home  

One of the easiest ways to minimize the risk of problems in your furnace overall is via consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a trained professional to check your furnace for broken-down parts, dirty filters and other likely problems can keep you from getting a big bill later on.  

It’s also beneficial to take a look at your furnace filters every few months – it’s recommended some filters be swapped out 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 more vigorously to complete its job. And the harder your furnace has to work, the more wear and tear pieces like the heat exchanger will sustain.