A steam-driven unit operates by forcing water through the coffee by using steam or steam pressure. The first espresso machines were steam types, produced when a common boiler was piped to four group heads so that multiple types of coffee could be made at the same time. This design is still used today in lower-cost consumer machines, as it does not need to contain moving parts. Also, steam-driven machines do not produce as high of a pressure for extraction compared to pump-driven. This results in the crema, a hallmark of an espresso, being of lower quality.
For first-time espresso machine owners, the Breville offers the perfect balance between hand-holding and customization. You’re in charge of basic steps like measuring out and pulling your shot, but the Breville makes it easy to adjust things like the coarseness of your grind and the amount of espresso. The user manual walks you through every step of the brewing process, and altering the default settings is easy, thanks to a display panel that clearly labels all buttons and lights. Our shots were beautifully layered and gave us truly gorgeous colors as the espresso flowed out of the portafilter.
Some machines use a single boiler kept at steaming temperature, but water for brewing is passed through a heat exchanger, taking some heat from the steam without rising to the same temperature. Although the water for brewing remains at a lower range than that required for steaming milk, it is still too hot for proper coffee extraction without first cooling; thus this type of machine requires a cooling flush of 4–6 seconds prior to the first espresso pull. Once the machine is dialed into the proper temperature, as many shots can be pulled as required without refreshing. However, if the user leaves the machine idle again for some period, the flushing process will need to be repeated. The HX variety is found in many mid-range machines and many users install thermometers to assist them is dialing in correct temperatures. There is some controversy as to the temperature stability of the brewing water, since it is indirectly converted from steaming temperature to brewing temperature, rather than kept at a brewing temperature.
The Rocket’s espresso lever is an upgrade from the simple on/off button used by most of our models. By only moving the lever part way up, you can play around with pre-infusing your coffee grounds before pulling the shot. Pre-infusion can be fun to tinker with as you try to home in on what makes your perfect espresso. This gives the Rocket an additional level of customization not available on the other models we tested.
Our brew-performance tests measure the brew temperature and contact time (how long water stays within a sweet spot of 195° to 205° F for brewing). We measure concentration using a refractometer, a device that measures the amount of coffee dissolved in each brew. Our convenience tests look at how easy it is to set timers, fill the reservoir, clean the machine, and more. And for the first time, we’re incorporating predicted reliability and owner satisfaction ratings into the new Overall Score for each model. We determine these ratings for each drip coffee maker brand using survey data collected from thousands of CR members.