Cracked Heat Exchanger

Q: My furnace guy just told me I need a new furnace immediately (can’t use the old one anymore at all). Apparently the heat exchanger is cracked, though our CO detector hasn’t gone off. Is this problem for real?

A: The fact that your carbon monoxide detector didn't go off isn't necessarily an indication that your furnace man is making up stories. A cracked heat exchanger is a genuine problem because it means that the dividing wall between the fire in your furnace and the air circulating in your home has been breached. This could allow combustion byproducts to enter your house, and that could be lethal. And given the cost of replacing the heat exchanger, furnace replacement is almost always the cheapest option. The good news is that modern, high-efficiency furnaces operate more economically than models made even as recently as 15 or 20 years ago. The money you spend on a new furnace will come back to you in fuel savings.