A furnace is usually a background player at home, ensuring you're warm across the cold winter months. It often won't be noticed until something goes wrong.
One root cause may be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s important to familiarize yourself with the symptoms of a cracked heat exchanger and what you should do if you believe 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 throughout the system. It usually accomplishes this with coils or tubes that heat up the air while functioning 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?
Thanks to its central role, it’s no surprise that a damaged heat exchanger can be very dangerous. A crack in the heat exchanger can allow dangerous gasses – such as carbon monoxide, which can be lethal – to circulate across your home.
For obvious reasons, do NOT turn on your furnace if you think you're dealing with a cracked heat exchanger, as this could make the whole family sick. Contact an HVAC professional right away if you are worried your furnace has a cracked heat exchanger that should be repaired.
Four Symptoms of a Cracked Heat Exchanger:
- Furnace shuts off: A crack in your heat exchanger could cause your furnace to turn off.
- Strange Smells: If the air leaving your furnace has a strong chemical scent, it may be a sign gasses are leaking through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm is triggered or you recognize 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 could struggle with signs of carbon monoxide poisoning. Complications include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel unwell, get out of the home as soon as you can and then call for help.
- Soot: If you see black sooty collecting around the exterior of your furnace, it’s another sign something may be seriously wrong.
What You Can Do if the Furnace Heat Exchanger is Cracked
If you worry your furnace has a cracked heat exchanger, contact a pro with extensive experience in furnace installation 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 run in the neighborhood of $1,000 to $3,000.
Estimates aside, the good news is that heat exchangers are often protected by the warranty. You’ll want to review the warranty paperwork on your furnace, because while the warranty might 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 most convenient ways to avoid problems in your furnace overall is through regular furnace maintenance. Furnaces work the best when they work efficiently. Hiring 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 beneficial to inspect your furnace filters every few months – it’s recommended some filters be replaced 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 accomplish its job. And the harder your furnace needs to run, the more strain parts like the heat exchanger will experience.