Heat exchange espresso machines offer simultaneous brew and steam functionality by employing a large steam boiler with an embedded brew boiler and a dual pump. They're easy to use and work well for the majority of home espresso enthusiasts who aren't interested in dialing in and playing around with different temperatures.
In this video, Gail explains to us what a heat exchanger is and how it works, then talks to us about models from Pasquini, Rocket Espresso and Nuova Simonelli.