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

September 20, 2022

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

One root cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to know the symptoms of a cracked heat exchanger and what you can do if you suspect that is the problem.

What Is a Heat Exchanger in a Furnace?

A heat exchanger helps transition heat from the combustion chamber inside your furnace to the air that moves inside the ventilation. It generally accomplishes this via coils or tubes that heat up the air while serving as a barrier to keep the gasses formed in the combustion chamber, called flue gasses, from getting out into your home.

Is a Cracked Heat Exchanger Dangerous?

Given its important role, it’s no surprise that a cracked 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 use your heating if you believe it has a cracked heat exchanger, as doing so could make your entire family ill. Reach out to an HVAC professional as soon as possible if you believe your heater has a cracked heat exchanger that needs repair.

Four Warning Signs of a Cracked Heat Exchanger:

  • Furnace switches off: A cracked heat exchanger can cause your furnace to turn off.
  • Unusual Smells: If the air escaping your furnace has a powerful chemical odor, it might be an indicator that gas is slipping through cracks in your heat exchanger. These byproducts, which will often smell like formaldehyde, are a significant warning sign.
  • Carbon monoxide alarm is triggered or you feel symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm could go off or household members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel sick, exit the home immediately and then call for help.
  • Soot: If you spot black sooty collecting on the exterior of your furnace, it’s more evidence something may be seriously wrong.

What to Do if the Furnace Heat Exchanger is Cracked

If you worry your furnace has a cracked heat exchanger, contact a professional well versed in furnace installation St. Louis right away so they can take a look at your system and, if required, start a furnace heat exchanger replacement. Costs often vary 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 often included in 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 could significantly lower 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 with routine furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Hiring a skilled professional to examine your furnace for worn-out parts, dirty filters and other potential 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 ideal some filters be swapped out every 90 days or sooner if they are dirty or grimy. While the filters are not part of the heat exchanger itself, the strain of pulling air through a clogged filter makes the entire furnace work more vigorously to do its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will experience.