A furnace is usually a background player for your home, helping keep you warm in the cold winter months. It often won't be noticed until something breaks down.
One root cause could be that your furnace has a cracked heat exchanger. It’s a potentially dangerous issue, so it’s worthwhile to learn 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 in your furnace to the air that moves through the ventilation. It generally does this through coils or tubes that heat the air while acting as a barrier to keep byproducts formed in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Thanks to its important role, it shouldn't come as a surprise that a broken heat exchanger can be very dangerous. A damaged heat exchanger can enable dangerous gasses – such as carbon monoxide, which can be lethal – to be distributed throughout your home.
For obvious reasons, never use your furnace if you suspect you're dealing with a cracked heat exchanger, as letting it run could make your entire family ill. Call an HVAC professional as soon as possible if you think your heating has a cracked heat exchanger that should be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace shuts off: A crack in your heat exchanger could cause your furnace to switch off.
- Strange Smells: If the air escaping your furnace has a strong chemical odor, it may be evidence gasses are seeping through cracks in your heat exchanger. These gasses, which can smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm goes off or you recognize symptoms of poisoning: If a cracked heat exchanger is emitting carbon monoxide inside your home, your carbon monoxide alarm could go off or household members might experience signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If an alarm goes off or you feel sick, get out of the home right away and then call for help.
- Soot: If you see black sooty accumulating on the exterior of your furnace, it’s an indication something could be seriously wrong.
What You Can Do if a Furnace Heat Exchanger is Cracked
If you believe your furnace has a cracked heat exchanger, call a professional experienced in furnace installation as soon as possible so they can take a look at your system and, if needed, start a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates run in the neighborhood of $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are regularly included in the warranty. It's a good idea to confirm the warranty paperwork on your furnace, since while the warranty may not 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 best ways to minimize the risk of problems in your furnace overall is through routine furnace maintenance. Furnaces work the best when they work efficiently. Calling a certified professional to examine your furnace for old parts, clogged filters and other potential problems can keep you from getting a big bill later on.
It’s also a good idea to take a look at 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 aren't a 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 has to work, the more strain components like the heat exchanger will sustain.