Signs of a Cracked Heat Exchanger

When it comes to heating your home, a cracked heat exchanger is your worst nightmare. This potential break in your furnace doesn’t mean your home doesn’t heat, but if it happens, it can be deadly. When a heat exchanger is cracked, it doesn’t filter the potentially toxic gases that aren’t supposed to go in your home, and this is a huge health hazard. Unfortunately, you can’t visibly see if a heat exchanger is cracked, but there are some signs you can watch for.

Signs of a Cracked Heat Exchanger

Flickering or Yellow Flame

A healthy furnace flame is blue and steady. When it is a yellow flame that moves, it can be a sign of a dirty burner or it means that your heat exchanger is cracked. Just to be safe, it is important to call a repair technician when your flame is yellow.


Gas furnaces are clean burning, so this means they do not normally produce soot. So if you see visible soot inside your furnace, it means it is no longer burning cleanly. Similar to a yellow flame, this can be caused by a cracked heat exchanger or an improperly adjusted burner.

Aromas and Physical Reactions

Usually, homeowners don’t really look inside their furnace for signs like a yellow flame or soot build up. For most, they don’t know they have a heat exchanger crack until they smell something or feel weird. Typically, a cracked heat exchanger means a foul aroma will start to enter your house. It smells like formaldehyde, but if you don’t know what that smells like, the smell will cause headaches, nausea, and sleepiness. If you smell something strange and start to feel these symptoms, turn off the furnace, open the windows, and call a heating repair service right away.

A cracked heat exchanger is a very serious problem to have, but if you suspect it is a problem you do have, contact us right away. Heat exchanger cracks cause deaths and need to be swiftly dealt with.

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