A furnace is often a background player in your home, helping keep you warm during the cold winter months. It often doesn’t get noticed until something breaks down.
One root cause may be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s worthwhile to know the evidence of a cracked heat exchanger and what to 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 of your furnace to the air that moves inside the air ducts. It generally does this with coils or tubes that heat 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?
Thanks to its central role, it shouldn't come as a surprise that a broken heat exchanger can be hazardous. A crack in the heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to flow throughout your home.
For obvious reasons, don't ever run your furnace if you believe there's a crack in the heat exchanger, as this could make your entire household ill. Reach out to an HVAC professional as soon as possible if you think your furnace has a cracked heat exchanger that should be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace turns off: Cracks in the heat exchanger can cause your furnace to shut off.
- Odd Smells: If the air coming out of your furnace has an intense chemical odor, it may be an indicator that gas is seeping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm is triggered or you notice symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide into your home, your carbon monoxide alarm could go off or household members may experience signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unwell, exit the home right away and then call for help.
- Soot: If you find black sooty buildup near the exterior of your furnace, it’s an indication something might be seriously wrong.
What to Do if a Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, call a pro well versed in furnace installation as soon as possible so they can examine your system and, if required, handle a furnace heat exchanger replacement. Costs often differ depending on the situation, but estimates can roughly suggest $1,000 to $3,000.
Estimates aside, the good news is that heat exchangers are generally covered by the warranty. You should review the warranty paperwork on your furnace, as while the warranty might not cover the entire cost of repairs, it could 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 trained professional to examine your furnace for broken-down parts, dirty filters and other potential problems can help you avoid getting a big bill later on.
It’s also helpful to inspect 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 aren't a part of the heat exchanger itself, the strain of pulling air through a clogged filter makes your entire furnace work harder to do its job. And the harder your furnace works, the more strain components like the heat exchanger will endure.