Is My Furnace’s Heat Exchanger Cracked? A Guide to the Signs

Closeup Shot Of Home Furnace Burner Ignited

You may not know what your furnace heat exchanger is, but it’s an important part of your furnace. The heat exchanger is the main component of your furnace.

Your heat exchanger is a system of metal coils surrounded by air. Your gas or electric connections heat the coils. The air around the coils then gets hot too. Then, the hot air is pushed through the ducts and vents of your home to heat it.

Since your furnace heat exchanger is such a critical piece of your furnace, it’s probably no surprise that you need it to be in good condition for your furnace to work. If it becomes damaged or cracked, not only will your furnace not work, but it is also dangerous. For your peace of mind, it’s essential that you know and recognize the signs that your furnace heat exchanger may be cracked.

Signs Your Heat Exchanger May Be Cracked

Knowing the signs that your heat exchanger may be cracked as a homeowner will help you care for your home. Here is what you need to know:

Strange Smells

When your furnace kicks on, you may notice a dusty odor as the air first moves through the ducts and vents. Within a few minutes, the smell should disappear. If you notice strange smells, like formaldehyde or any other strong chemical smell, it strongly indicates that your heat exchanger is cracked. It also means dangerous gasses, like carbon monoxide, are leaking into your home. You should immediately evacuate and call 911.

Soot Buildup

Soot buildup around your furnace signifies that the gasses used to heat the heat exchanger coils only partially combust. This is another critically dangerous situation because when gasses partially combust, you’re left with carbon monoxide. It’s essential to call for emergency repair services right away.


If moisture enters your furnace, it can cause corrosion. Over time, the corrosion will break down the metal of your furnace. As the metal breaks down, cracks in the heat exchanger could happen. Once again, dangerous gasses could leak into your home.

Flame Appearance

The pilot light or heat flame in your furnace should be blue. A blue flame means your fuel is completely burning. If your flame is yellow or another off-color, your fuel is burning inefficiently, which could mean your heat exchanger is cracked.

Recurring Flu Symptoms

If you’ve been feeling sick on and off for a while without knowing why, it’s worth checking your heating system. A slow carbon monoxide leak from a cracked heat exchanger can cause the people in your home to experience flu-like symptoms.

Furnace Won’t Work

Usually, a furnace that won’t work is a nuisance, but in this case, it is a blessing! It means you will have an opportunity to realize the heat exchanger is cracked before carbon monoxide leaks into your home — or worse!

Carbon Monoxide Detectors Keep Going Off

If your carbon monoxide goes off, it’s worth checking your furnace for a cracked heat exchanger. As one of the largest appliances in your home, your furnace is also one of the most significant sources of carbon monoxide.

Need Services? We Can Help!

If you notice any of these signs, don’t wait to call for help — and don’t try to fix your furnace on your own! Cracked heat exchangers are dangerous and should only be handled by experienced and trained professionals.

Why Choose Blind & Sons?

Homeowners in Northeast Ohio value dedication and experience. At Blind & Sons, we have served Akron-area homeowners for over 80 years. We care about our customers because you are our friends and neighbors.

Trust your home to us when you need furnace repair or replacement services. In addition to superior quality, we also offer 24/7 emergency service with no overtime fees and a 100% satisfaction guarantee.

Wondering if your heat exchanger is cracked? Let our experts help you! Call us at (330) 753-7711 or contact us online to schedule your appointment today!

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