An electric drip coffee maker can also be referred to as a dripolator. It normally works by admitting water from a cold water reservoir into a flexible hose in the base of the reservoir leading directly to a thin metal tube or heating chamber (usually, of aluminum), where a heating element surrounding the metal tube heats the water. The heated water moves through the machine using the thermosiphon principle. Thermally-induced pressure and the siphoning effect move the heated water through an insulated rubber or vinyl riser hose, into a spray head, and onto the ground coffee, which is contained in a brew basket mounted below the spray head. The coffee passes through a filter and drips down into the carafe. A one-way valve in the tubing prevents water from siphoning back into the reservoir. A thermostat attached to the heating element turns off the heating element as needed to prevent overheating the water in the metal tube (overheating would produce only steam in the supply hose), then turns back on when the water cools below a certain threshold. For a standard 10-12 cup drip coffeemaker, using a more powerful thermostatically-controlled heating element (in terms of wattage produced), can heat increased amounts of water more quickly using larger heating chambers, generally producing higher average water temperatures at the spray head over the entire brewing cycle. This process can be further improved by changing the aluminum construction of most heating chambers to a metal with superior heat transfer qualities, such as copper.
Our top pick is the OXO On 12-Cup Coffee Brewing System. It’s a large machine – both in footprint and in capacity — but it earned the second-highest scores in our taste test, and is sleek both to look at and to operate. Convenient features like programmable auto-brewing, a removable water reservoir that doubles as a kettle, and a spigot that stops the brew mid-stream if you remove the carafe make this machine feel high tech without being high maintenance. For those who want to be a little more hands-on with the brewing process, its single-button dial also lets you adjust the water’s brewing temperature, giving you more access to experiment with extraction and flavor.
This testing was designed to highlight the difference in how each machine extracted its coffee grounds. Remember, extraction is tied to water temperature, how long the grounds had to steep, and how evenly that water is distributed in the brew basket. (Depending on how the machine distributes the water and the shape of the basket, any particular ground may or may not receive the same amount of time in contact with water — thus any individual grind may be over-extracted, under-extracted, or just right.) Properly extracted grounds would have a balance of notes and aromas, from slight hints of acid to a pleasant amount of bitterness.
The machine is super easy to use: just choose either a single or double shot, select your coffee grounds, fill the milk and water reservoir and choose your brew. The water reservoir is removable, allowing for easy fill-up in the sink. The Café Barista also boasts the fastest preparation time when compared to other Mr. Coffee espresso makers. And at less than $200, this model is WAY less expensive than some of its competitors, giving you a great bang for your buck.
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.