Million-Air™ Heat Exchanger The heart of your Amana® Brand furnaces is its patented Million-Air™ stainless-steel tubular heat exchanger. Formed using our patented, dual-diameter pipe and wrinkle-bend technologies, the Million-Air is built to last. One of these heat exchangers has endured over one million extreme-temperature test cycles, and is still going strong. The durability of this heat exchanger is one of the reasons we know your Amana brand furnace will last for years to come.