Cracked Heat Exchanger: What That Means and What You Should Do Next

September 20, 2022

A furnace is almost always a background player for your home, ensuring you're warm in the cold winter months. It often won't be noticed until a malfunction appears.

One source might 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 you can do if you suspect that may be 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 flows through the system. It typically accomplishes this through coils or tubes that heat up the air while functioning as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from leaking out into your home.

Is a Cracked Heat Exchanger Dangerous?

Because of its central role, it’s no surprise that a cracked heat exchanger can pose a risk. Cracks in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to flow through your home.

For that reason, do NOT run your furnace if you suspect there's a crack in the heat exchanger, as letting it run could make the entire household sick. Reach out to an HVAC professional as soon as possible if you believe your heating has a cracked heat exchanger that needs repair.

Four Signs of a Cracked Heat Exchanger:

  • Furnace switches off: A crack in your heat exchanger can cause your furnace to turn off.
  • Unusual Smells: If the air leaving your furnace has a powerful chemical odor, it might be a sign gas is slipping through cracks in your heat exchanger. These gasses, which can 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 emitting carbon monoxide in your home, your carbon monoxide alarm should go off or household members could experience signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. 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 another sign something might be seriously wrong.

What You Can Do if the Furnace Heat Exchanger is Cracked

If you believe your furnace has a cracked heat exchanger, call a pro experienced in furnace installation Temple/Belton right away so they can take a look at your system and, if required, perform a furnace heat exchanger replacement. Costs will vary depending on the situation, but estimates can roughly suggest $1,000 to $3,000.

However, the good news is that heat exchangers are regularly included in the warranty. You should review the warranty paperwork on your furnace, since while the warranty may not cover the entire cost of repairs, it can significantly lower your bill.

How to Prevent a Cracked Heat Exchanger in Your Home

One of the most convenient ways to minimize the risk of problems in your furnace overall is via regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a skilled professional to examine your furnace for old parts, clogged filters and other likely problems can help you avoid getting a big bill later on.

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