Espresso makers are complex machines, and even the simple ones come with a lot of features other coffee makers don't have. People new to home espresso machines might not know what all of these features do or why they're important. Here is a quick rundown on the most common features and how they work to make a great cup of espresso.
Fully Versus Semi-Automatic Operation
The first thing many people notice about a new espresso machine is how much work it takes to operate it. Fully automatic machines can do every step of the process, from grinding the beans to steaming the milk. People who prefer more control over their coffee can opt for a semi-automatic model that takes more intervention.
One Versus Two Boilers
Most espresso machines come with either one or two boilers. Single-boiler machines have relatively simple internals and tend to be less expensive, but they're limited in what they can do. The ideal temperature for water is 190-196 degrees, while milk foam is most stable at 150 degrees and it "breaks" above 170. With two boilers, it's possible to heat both up to their ideal range at the same time.
Steam Pressure Versus Pump
Water for espresso needs to be pushed through the grounds at higher pressures than drip coffee can manage. While drip water falls at 1 bar, which is normal air pressure at sea level, espresso water has to hit the grounds at between 7 and 9 bars. This pressure can be generated in a few ways, but two are far more popular than the others: steam and pump.
The earliest espresso machines, notably the iconic Moko, used internal steam pressure from the water itself for the steep. This can be mechanically simple, as in the Moko, which has no moving parts, but it's inexact and slow. Pump machines are faster and more practical, since they allow finer control over the process. Pumps can be manual or electric.
Cost: Brewer Versus Grinder
Making espresso starts with grinding the beans. Some machines have built-in grinders, but those that don't need to be paired with a grinder. Both pieces of equipment should be included in the same budget, since they work so closely together. Where the budget gets allocated is a judgment call for each user, but it's usually a mistake to go cheap on one component in favor of the other.
As a rule, both machines have a financial sweet spot. Espresso machines hit their stride somewhere between $250 and $750, with not enough features below that level and diminishing returns above it. The best grinders tend to run higher than $50, but spending more than $200 is probably overkill.