The term dual boiler is used narrowly for machines with two separate boilers, and more broadly for what are more properly called dual heater (DH) machines, featuring a boiler for brewing and a separate thermoblock (TB) for heating brew water to steaming temperature – opposite to HX machines, where the boiler is at steaming temperature and is cooled to brewing temperature.
In the semi-automatic machine, water pressure and temperature must be stable and consistent, and according to our expert, the pressure shouldn't be too high. Typically, coffee is brewed at a pressure of about 10 bars, and an ideal water temperature is around 195 degrees. Generally, the more expensive the machine, the better the equipment inside that regulates these two factors. High-quality machines tend to have a mechanism called a PID, or proportional-integral-derivative, controller. The PID's function is to maintain constant water temperature with extreme accuracy, down to the degree. Two central problems plaguing inexpensive espresso machines is that they lack a PID, meaning the temperature of the brewing water can fluctuate up and down and yield inconsistent results. Inexpensive machines often advertise that they have 15 or 20 bars of pressure as a selling point. But, higher pressure is not the priority, and too much pressure can actually lead to over-extraction and bitterness in your espresso shot. Therefore, we looked for a machine with good temperature and pressure control.
The Bonavita Coffee Brewer performs stellar when it comes to coffee drip brewing, easily outpacing more expensive coffee makers. It'll take about six minutes to create 44 ounces of coffee. Brisk brewing has caught the attention of the Specialty Coffee Association of America, since it's threshold for recognition is a brewing time of fewer than eight minutes.
While we love the all-inclusive features of the Breville, there’s one thing it can’t do on its own, at least not without a hefty repair bill. If you love dark roasts, any machine that features an internal grinder is off-limits. The oily shine characteristic of dark roasts builds up in any grinder — but while you can disassemble and clean standalone grinders, this is rarely an option for internal ones. The residual oil left in an internal grinder will, at best, give future shots a rancid flavor. At worst, the oil will clog the grinder. If you want to brew dark roasts on the Breville, plan on buying a separate grinder.
“We are a Cuisinart family. My mom still has the same food processor from the 1980s on the counter. When my co-host (and brother) Darin and I were looking for a coffee maker for our studio, that was the only choice for us. We loved this one because you set the time and forget it. We always work late, so this is a really nice end-of-day step, and then you get going without the bleariness of the morning. The thermal is a must as we drink throughout the day, and it’s great to just have it hot when we’re ready.” — Greg Bresnitz, co-host of Snacky Tunes
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.