A furnace is usually a background player at home, helping keep you warm during the cold winter months. It regularly doesn’t get noticed until something goes wrong.
One source might be that your furnace has a cracked heat exchanger. It can potentially be hazardous, so it’s critical to know the signs of a cracked heat exchanger and what you should do if you are worried that is the problem.
What Is a Heat Exchanger in a Furnace?
A heat exchanger helps transition heat from the combustion chamber of your furnace to the air that flows throughout the system. It generally does this via coils or tubes that heat up 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 important role, it isn't surprising 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 through your home.
For that reason, do NOT use your heating if you believe it has a cracked heat exchanger, as this could make the entire household sick. Call an HVAC professional immediately if you think your furnace has a cracked heat exchanger that should be repaired.
Four Signs of a Cracked Heat Exchanger:
- Furnace turns off: Cracks in the heat exchanger may cause your furnace to turn off.
- Unusual Smells: If the air leaving your furnace has a strong chemical scent, it may be evidence gas is leaking through cracks in your heat exchanger. These gasses, which will often smell like formaldehyde, are a significant warning sign.
- Carbon monoxide alarm is triggered or you feel health problems: If a cracked heat exchanger is releasing carbon monoxide into your home, your carbon monoxide alarm should go off or family members could experience signs of carbon monoxide poisoning. Symptoms 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 notice black sooty collecting around the exterior of your furnace, it’s an indication something could be seriously wrong.
What to Do if the Furnace Heat Exchanger is Cracked
If you worry your furnace has a cracked heat exchanger, hire a pro with extensive experience in furnace installation right away so they can take a look at your system and, if needed, perform 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 generally protected by the warranty. You’ll want to check the warranty paperwork on your furnace, because 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 easiest ways to avoid problems in your furnace overall is with consistent furnace maintenance. Furnaces offer the most benefits when they work efficiently. Hiring a certified professional to check your furnace for broken-down parts, clogs in the air filters and other likely problems can help you avoid getting a big bill later on.
It’s also a good idea to inspect your furnace filters every few months – it’s recommended 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 pulling air through a clogged filter makes the entire furnace work harder to do its job. And the harder your furnace works, the more deterioration pieces like the heat exchanger will sustain.