A furnace is almost always a background player at home, helping keep you warm across the cold winter months. It regularly isn't noticed until a malfunction appears.
One root cause might be that your furnace has a cracked heat exchanger. It can be a safety risk, so it’s important to familiarize yourself with the signs of a cracked heat exchanger and what to do if you suspect that may be the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger transfers heat from the combustion chamber of your furnace to the air that moves throughout the ventilation. It typically does this via coils or tubes that warm the air while serving 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?
Because of its central role, it’s no surprise that a cracked heat exchanger can be very dangerous. A damaged heat exchanger can enable dangerous gasses – including carbon monoxide, which can be lethal – to be distributed across your home.
For that reason, never turn on your heating if you suspect there's a crack in the heat exchanger, as doing so could make the whole family ill. Contact an HVAC professional as soon as possible if you are worried your furnace has a cracked heat exchanger that needs repair.
Four Warning Signs of a Cracked Heat Exchanger:
- Furnace turns off: Cracks in the heat exchanger could cause your furnace to turn off.
- Odd Smells: If the air coming out of your furnace has a powerful chemical odor, it could be a sign gas is leaking through cracks in your heat exchanger. These byproducts, which can smell like formaldehyde, are a major warning sign.
- Carbon monoxide alarm initiates or you feel symptoms of poisoning: If a cracked heat exchanger is relieving carbon monoxide into your home, your carbon monoxide alarm could go off or household members might start experiencing signs of carbon monoxide poisoning. Symptoms include headaches, dizziness, weakness, nausea, vomiting or feeling sleepy. If the alarm goes off or you feel sick, leave the home right away and then call for help.
- Soot: If you find black sooty accumulating near the exterior of your furnace, it’s another sign something could be seriously wrong.
What You Can Do if Your Furnace Heat Exchanger is Cracked
If you suspect your furnace has a cracked heat exchanger, call a pro with extensive experience in furnace installation as soon as possible so they can take a look at your system and, if required, handle a furnace heat exchanger replacement. Costs should vary depending on the situation, but estimates often hover around $1,000 to $3,000.
Fortunately, the good news is that heat exchangers are regularly covered by the warranty. It's a good idea to review the warranty paperwork on your furnace, as while the warranty may 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 most convenient ways to prevent a problem in your furnace overall is through regular furnace maintenance. Furnaces provide the best possible return on investment when they run efficiently. Hiring a certified professional to inspect your furnace for worn-out parts, clogged filters and other common 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 recommended some filters be replaced 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 pulling air through a clogged filter makes your entire furnace work longer to complete its job. And the harder your furnace works, the more deterioration pieces like the heat exchanger will endure.