Cracked Heat Exchanger: What That Means and What to Do Next

September 20, 2022

A furnace is almost always a background player at home, keeping you warm during the cold winter months. It often isn't noticed until something goes wrong.

One source may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to learn the evidence 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 of your furnace to the air that flows throughout the system. It typically does 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 getting out into your home.

Is a Cracked Heat Exchanger Dangerous?

Thanks to its key role, it’s no surprise that a damaged heat exchanger can be very dangerous. Cracks in the heat exchanger can permit dangerous gasses – like carbon monoxide, which can be lethal – to be distributed throughout your home.

For this reason, do NOT turn on your heater if you think there's a crack in the heat exchanger, as doing so could make your entire family ill. Contact an HVAC professional right away if you think your heating has a cracked heat exchanger that needs to be repaired.

Four Signs of a Cracked Heat Exchanger:

  • Furnace switches off: Cracks in the heat exchanger can cause your furnace to turn off.
  • Odd Smells: If the air coming out of your furnace has a powerful chemical smell, it might be an indicator that gas is seeping through cracks in your heat exchanger. These byproducts, which will often 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 into your home, your carbon monoxide alarm should go off or family members might struggle with signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If the alarm goes off or you feel sick, leave the home right away and then call for help.
  • Soot: If you find black sooty buildup near the exterior of your furnace, it’s more evidence something could be seriously wrong.

What You Should Do if the Furnace Heat Exchanger is Cracked

If you worry your furnace has a cracked heat exchanger, call a professional experienced in furnace installation Huntsville right away so they can examine your system and, if required, handle a furnace heat exchanger replacement. Costs often fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.

Estimates aside, the good news is that heat exchangers are regularly covered by the warranty. You should confirm the warranty paperwork on your furnace, because while the warranty may 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 best ways to prevent a problem in your furnace overall is through consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Contacting a skilled professional to examine your furnace for worn-out parts, clogs in the air filters and other likely problems can keep you from getting a big bill later on.

It’s also beneficial to inspect 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 dragging air through a clogged filter makes the entire furnace work harder to complete its job. And the harder your furnace needs to run, the more deterioration parts like the heat exchanger will endure.