A furnace is often a background player in your home, keeping you warm across the cold winter months. It often won't be noticed until something goes wrong.
One cause might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s important to know the evidence of a cracked heat exchanger and what to do if you believe 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 air ducts. It usually handles this through coils or tubes that warm the air while serving as a barrier to keep the gasses created in the combustion chamber, called flue gasses, from escaping out into your home.
Is a Cracked Heat Exchanger Dangerous?
Because of its central role, it shouldn't come as a surprise that a cracked heat exchanger can be very dangerous. A damaged heat exchanger can enable dangerous gasses – like carbon monoxide, which can be lethal – to circulate throughout your home.
For that reason, don't ever turn on your furnace if you think there's a crack in the heat exchanger, as doing so could make your entire family sick. Contact an HVAC professional right away if you believe your furnace has a cracked heat exchanger that needs to be repaired.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace shuts off: A crack in your heat exchanger may cause your furnace to switch off.
- Strange Smells: If the air escaping your furnace has an intense chemical odor, it may be a sign gasses are 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 poisoning symptoms: If a cracked heat exchanger is relieving carbon monoxide inside your home, your carbon monoxide alarm may go off or household members may start experiencing signs of carbon monoxide poisoning. Side effects include headaches, dizziness, weakness, nausea, vomiting or feeling tired. If the alarm goes off or you feel unusually tired, exit the home as soon as you can and then call for help.
- Soot: If you spot 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 suspect your furnace has a cracked heat exchanger, hire a professional well versed in furnace installation as soon as possible so they can examine your system and, if required, start a furnace heat exchanger replacement. Costs will differ depending on the situation, but estimates often hover around $1,000 to $3,000.
Estimates aside, the good news is that heat exchangers are often included in the warranty. You’ll want to confirm the warranty paperwork on your furnace, because while the warranty won't always cover the entire cost of repairs, it still may significantly lower your bill.
How to Prevent a Cracked Heat Exchanger in Your Home
One of the most convenient ways to minimize the risk of problems in your furnace overall is with routine furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Calling a skilled professional to check your furnace for broken-down parts, dirty filters and other common problems can help you avoid 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 encouraged 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 dragging air through a clogged filter makes your entire furnace work longer to accomplish its job. And the harder your furnace has to work, the more strain parts like the heat exchanger will endure.