A furnace is almost always a background player at home, ensuring you're warm during the cold winter months. It often won't be noticed until a malfunction appears.
One root cause may be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to familiarize yourself with the signs of a cracked heat exchanger and what you should do if you suspect that is the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps move heat from the combustion chamber inside your furnace to the air that flows throughout the system. It usually handles this through coils or tubes that heat the air while acting as a barrier to keep the gasses produced in the combustion chamber, called flue gasses, from getting out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its central role, it’s no surprise that a cracked heat exchanger can pose a risk. Cracks in the heat exchanger can permit dangerous gasses – including carbon monoxide, which can be lethal – to flow throughout your home.
For that reason, don't ever turn on your furnace if you suspect it has a cracked heat exchanger, as doing so could make the entire family sick. Reach out to an HVAC professional immediately if you believe your furnace has a cracked heat exchanger that needs to 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.
- Odd Smells: If the air escaping your furnace has a powerful chemical smell, it could be a sign gasses are slipping through cracks in your heat exchanger. These gasses, which may smell like formaldehyde, are a common warning sign.
- Carbon monoxide alarm is triggered or you recognize symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm should go off or household members may experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling drowsy. If your alarm goes off or you feel unusually tired, get out of the home right away and then call for help.
- Soot: If you see black sooty collecting around the exterior of your furnace, it’s another sign something might be seriously wrong.
What You Should Do if Your Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, call a pro experienced in furnace installation as soon as possible so they can examine your system and, if needed, start a furnace heat exchanger replacement. Costs should fluctuate depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
However, the good news is that heat exchangers are often covered by the warranty. You should 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 easiest ways to prevent a problem in your furnace overall is via consistent furnace maintenance. Furnaces offer the most benefits when they operate efficiently. Calling a skilled professional to check your furnace for old parts, clogs in the air filters and other potential problems can help you avoid getting a big bill later on.
It’s also helpful to review 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 connected to the heat exchanger itself, the strain of drawing air through a clogged filter makes the entire furnace work longer to do its job. And the harder your furnace works, the more wear and tear components like the heat exchanger will sustain.