Cracked Heat Exchanger: What It Means and What You can Do Next

September 20, 2022

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

One root cause could be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to learn the symptoms of a cracked heat exchanger and what to do if you believe that might 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 circulates throughout the ventilation. It typically handles this through coils or tubes that heat up the air while acting 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?

Given its central role, it’s no surprise that a damaged heat exchanger can be very dangerous. Cracks in the heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to flow throughout your home.

For that reason, do NOT turn on your furnace if you think it has a cracked heat exchanger, as this could make the entire family ill. Contact an HVAC professional right away if you are worried your furnace has a cracked heat exchanger that should be repaired.

Four Warning Signs of a Cracked Heat Exchanger:

  • Furnace switches off: A crack in your heat exchanger may cause your furnace to switch off.
  • Strange Smells: If the air coming out of your furnace has an intense chemical odor, it might be an indicator that gasses are seeping through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a common warning sign.
  • Carbon monoxide alarm goes off or you feel symptoms of poisoning: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm may go off or household members could experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If your alarm goes off or you feel unusually tired, leave the home immediately and then call for help.
  • Soot: If you notice black sooty collecting near the exterior of your furnace, it’s another sign something may be seriously wrong.

What to Do if a Furnace Heat Exchanger is Cracked

If you worry your furnace has a cracked heat exchanger, hire a pro experienced in furnace installation Mankato area right away so they can take a look at your system and, if needed, handle a furnace heat exchanger replacement. Costs should 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 generally covered by the warranty. You’ll want to review the warranty paperwork on your furnace, since while the warranty won't always 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 best ways to avoid problems in your furnace overall is through routine furnace maintenance. Furnaces offer the most benefits when they run efficiently. Hiring a certified professional to check your furnace for broken-down parts, clogs in the air filters and other likely problems can keep you from 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 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 pulling air through a clogged filter makes the entire furnace work more vigorously to complete its job. And the harder your furnace needs to run, the more deterioration pieces like the heat exchanger will endure.