An early variant technique, called a balance siphon, was to have the two chambers arranged side-by-side on a sort of scale-like device, with a counterweight attached opposite the initial (or heating) chamber. Once the near-boiling water was forced from the heating chamber into the brewing one, the counterweight was activated, causing a spring-loaded snuffer to come down over the flame, thus turning "off" the heat, and allowing the cooled water to return to the original chamber. In this way, a sort of primitive 'automatic' brewing method was achieved.
The principle of a vacuum brewer was to heat water in a lower vessel until expansion forced the contents through a narrow tube into an upper vessel containing ground coffee. When the lower vessel was empty and sufficient brewing time had elapsed, the heat was removed and the resulting vacuum would draw the brewed coffee back through a strainer into the lower chamber, from which it could be decanted. The Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925.
CR’s take: Like the model above, the Cuisinart Burr Grind & Brew takes whole coffee beans and grinds them fresh for each pot. It features programming, brew-strength control, a water filter, a permanent coffee filter, and auto-shutoff. This model earns a great rating for carafe handling. The stainless steel finish and glass carafe certainly elevate the experience of using it. Cuisinart brewers also received an Excellent rating for owner satisfaction. But the performance and finish come at a premium—this machine costs significantly more than the Black+Decker Mill & Brew.
All of the espresso machines we tested only included a single boiler for heating. This means that there's only one mechanism for heating both the water for brewing and the steamer wand. Because of this, it'll take the steamer wand a while to heat up after pulling the espresso shot, since the steamer wand operates at a much higher temperature than the brewing temperature of around 195°F. It is possible to buy a home machine with a double boiler (Breville makes one) but this raises the price significantly (we didn't test the Breville because it's over $1,000), and the minor wait time wasn't a major concern for us. We figured it wouldn't be for home brewers either.
First, of all of the espresso machines we tested, the two Breville models are the only ones that contain the above-mentioned PID for extremely precise temperature control. This means that the machine consistently pulled a slightly-sweet, creamy shot of espresso. It had plenty of crema on top. Another reason this machine pulls such a consistently wonderful shot is that it maintains consistent pressure—where other machines made bitter, flat-tasting shots, the consistent pressure of the Breville machine meant the espresso was flavorful and delicious.
On August 27, 1930, Inez H. Pierce of Chicago, Illinois filed patent for the first vacuum coffee maker that truly automated the vacuum brewing process, while eliminating the need for a stove top burner or liquid fuels. An electrically heated stove was incorporated into the design of the vacuum brewer. Water was heated in a recessed well, which reduced wait times and forced the hottest water into the reaction chamber. Once the process was complete, a thermostat using bi-metallic expansion principles shut off heat to the unit at the appropriate time. Pierce's invention was the first truly "automatic" vacuum coffee brewer, and was later incorporated in the Farberware Coffee Robot.
If tinkering is what you’re most excited about, we recommend the Behmor Brazen Plus Customizable Temperature Control Brew System. This is a drip machine that takes its job seriously. It performed the very best in our out-of-the-box taste testing, but still gives you the opportunity to play around with different variables, from water temperature to pre-infusion times. At around $200, it’s on-par with the OXO 9-Cup price-wise, but is definitely not as nice to look at or use, with a tall, bulbous body, squat carafe, and an eight-button programmable interface that reminded us of a digital alarm clock.
No one wants to wait in line for espresso, right? This machine lets you make two shots at once, so you can make drinks for two in half the time, and you can choose a single- or double-shot portafilter for different serving sizes. The machine has a 15-bar pump system and a frothing arm to make a creamy froth for your cappuccinos and lattes. An indicator light lets you know when the process is complete.
Because the coffee grounds remain in direct contact with the brewing water and the grounds are filtered from the water via a mesh instead of a paper filter, coffee brewed with the cafetiere captures more of the coffee's flavour and essential oils, which would become trapped in a traditional drip brew machine's paper filters. As with drip-brewed coffee, cafetiere coffee can be brewed to any strength by adjusting the amount of ground coffee which is brewed. If the used grounds remain in the drink after brewing, French pressed coffee left to stand can become "bitter", though this is an effect that many users of cafetiere consider beneficial. For a 1⁄2-litre (0.11 imp gal; 0.13 US gal) cafetiere, the contents are considered spoiled, by some reports, after around 20 minutes. Other approaches consider a brew period that may extend to hours as a method of superior production.
CR’s take: Though this Bialetti lacks typical drip-machine features such as programming and brew-strength control, it more than compensates with a Very Good rating in our brew performance test and a crisp 8-minute brew time. If you’re the type who sometimes prefers a morning shot of espresso to a cup of joe, this twofer—drip machine beside espresso maker—may be for you. It features a built-in milk frother, a permanent coffee filter, and auto-shutoff. CR does not yet have enough survey data on Bialetti machines to rate them on reliability and satisfaction, but when we do, we’ll add that info to our ratings.