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.
CR’s take: This Cuisinart drip coffee maker with a stainless steel finish and glass carafe earns an Excellent rating for brew performance. It’s programmable and features a water filter, a permanent coffee filter, cleaning mode, a cleaning indicator, and auto-shutoff. The machine also allows you to adjust the strength of your brew. For the money, this model offers style and features that are hard to beat. If you can live without the built-in grinder of the Cuisinart Burr Grind & Brew above, you can save yourself some money and still enjoy Cuisinart quality for a lot less.
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.
For many of us, the daily grind can't begin until we've had that first cup of piping hot coffee—so the right brewer is at the top of the list. The most basic coffee makers make at least a decent cup, but a little more money buys conveniences such as programmability, a thermal carafe to keep coffee hot longer, settings that let you adjust brew strength, and more.