It also automatically pre-infuses the coffee, allowing the grounds to vent their CO2 and “bloom.” Remember, only half of the machines we tested had this feature, and it proved to pay off in our taste tests. The four machines we recommend all pre-infuse. Only one coffee maker without it, the Hamilton Beach, performed well at all in our taste tests — but that guy was so cheap and flimsy, part of the brew basket broke during our testing. Sorry, Hamilton Beach.
The bottom chamber contains the water. The middle chamber is a filter-basket holding the ground coffee and sits within the bottom chamber. The top chamber, with a metal filter, screws onto the bottom chamber. When the pot is heated on a stove, the pressure from the steam in the bottom chamber forces the water through a tube into the filter-basket, through the ground coffee, the metal filter, and it then funnels into the top chamber where the coffee is then ready to serve. They are commonly found in Italy, Spain and Portugal. They are also known as a macchinetta, Italian for little machine or caffettiera, Italian for coffee maker.