Bunn-O-Matic came out with a different drip-brew machine. In this type of coffeemaker, the machine uses a holding tank or boiler pre-filled with water. When the machine is turned on, all of the water in the holding tank is brought to near boiling point (approximately 200–207 °F or 93–97 °C) using a thermostatically-controlled heating element. When water is poured into a top-mounted tray, it descends into a funnel and tube which delivers the cold water to the bottom of the boiler. The less-dense hot water in the boiler is displaced out of the tank and into a tube leading to the spray head, where it drips into a brew basket containing the ground coffee. The pourover, water displacement method of coffeemaking tends to produce brewed coffee at a much faster rate than standard drip designs. Its primary disadvantage is increased electricity consumption in order to preheat the water in the boiler. Additionally, the water displacement method is most efficient when used to brew coffee at the machine's maximum or near-maximum capacity, as typically found in restaurant or office usage. In 1963, Bunn introduced the first automatic coffee brewer, which connected to a waterline for an automatic water feed.
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.
With its mid-century design and an exposed reservoir, you'll want to leave the Moccamaster out on the counter even when it’s not in use. But it doesn't just look great. Indeed, the pricey Moccamaster brews a complex and smooth pot of coffee that ranked highest in our taste test. This machine also fills a full pot quickly—a necessity for the morning rush.
“This little espresso maker is just awesome! It is fun to use and always makes a great cup of espresso. I’ve used it to make macchiatos, affogatos, and as a espresso shot to my coffee. The simplicity of this stovetop espresso maker is amazing. You won’t get as much crema as you would with an espresso machine but the aroma and taste are unmatched. I’ve had the three-cup model for a few months now, and I use it often. I’ve had no problems with it at all. After it use I just rinse it with warm water and let it air dry.”
The next is the machine’s auto-pause. If you remove the carafe before your full pot is done brewing, the flow will stop until the carafe goes back in. It’s not a perfect system. There are a few inevitable drips that add an extra step to clean-up, and if the water is held up in the brew basket for too long, it increases the chance of over-extraction. But if you want a great first cup to sip on while the rest of your pot is brewing, you’ll get it in a much more satisfying time frame.
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.