A furnace is often a background player in your home, helping keep you warm in the cold winter months. It frequently won't be noticed until something breaks down. 

One cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s critical to learn the signs 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 transfers heat from the combustion chamber in your furnace to the air that moves through the air ducts. It usually handles this using coils or tubes that heat the air while serving as a barrier to keep gas created in the combustion chamber, called flue gasses, from escaping out into your home.  

Is a Cracked Heat Exchanger Dangerous? 

Given its central role, it isn't surprising that a damaged heat exchanger can pose a risk. A damaged heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to flow through your home. 

For that reason, never use your heater if you believe it has a cracked heat exchanger, as doing so could make the whole family ill. Contact an HVAC professional right away if you believe your heater has a cracked heat exchanger that should be repaired. 

Four Symptoms of a Cracked Heat Exchanger: 

  • Furnace turns off: A cracked heat exchanger can cause your furnace to switch off. 
  • Odd Smells: If the air leaving your furnace has an intense chemical scent, it might be evidence gas is slipping through cracks in your heat exchanger. These byproducts, which may smell like formaldehyde, are a significant warning sign. 
  • Carbon monoxide alarm goes off or you feel symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide in your home, your carbon monoxide alarm should go off or household members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If your alarm goes off or you feel sick, get out of the home right away and then call for help. 
  • Soot: If you find black sooty collecting on the exterior of your furnace, it’s another sign something could be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked 

If you suspect your furnace has a cracked heat exchanger, contact a professional experienced in furnace installation Mason City as soon as possible so they can examine your system and, if required, perform a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000. 

Fortunately, the good news is that heat exchangers are generally protected by the warranty. You should confirm the warranty paperwork on your furnace, because while the warranty might not cover the entire cost of repairs, it can significantly reduce your bill.  

How to Prevent a Cracked Heat Exchanger in Your Home  

One of the easiest ways to avoid problems in your furnace overall is via routine furnace maintenance. Furnaces offer the most benefits when they run efficiently. Hiring a trained professional to examine your furnace for worn-out parts, clogged filters and other likely problems can help you avoid getting a big bill later on.  

It’s also a good idea to review 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 drawing air through a clogged filter makes your entire furnace work harder to accomplish its job. And the harder your furnace works, the more deterioration components like the heat exchanger will endure.