First look at coffee machine's productivity, focusing on the conditions under which it will be used (home or office), as well as how often and how much coffee it will make. Productivity is calculated by several parameters. First, the number of cups of coffee per hour: the modern espresso makers are capable of making from 20 to 100 or more servings of coffee. Secondly, the size of the boiler, that affects the amount of hot water and steam produced by espresso machine for one cycle of heating. It is desirable that espresso maker heat the water in a boiler in a very short time - less than 15 minutes. Some models are equipped with a second additional thermocouple, significantly accelerating the heating, and mini boiler. Having a second thermocouple or a mini boiler has no effect on taste and quality of drink, but significantly reduces pause when switching espresso maker from the espresso making mode into the mode of vaporization.
Some automatic espresso machines are connected directly to the water supply - they are designed to prepare the tens and hundreds of cups of coffee per hour.
Volume of water tanks under the espresso (1 to 2.5 liters and professional and office espresso makers can reach up to 5-6 liters), the volume of a bunker for coffee bean (from 200 to 1500 grams) and volume of waste tray (15-20 servings ) are also important parameters which indicate performance of an espresso maker.
Preliminary grind is a function, in which the coffee is ground for the second portion while preparing the first. As a result, the cooking time of each new portion is reduced.
The function of automatic dosing, which is available in most of the fully automatic espresso makers, provides the required ratio of water and coffee in a finished product. "Advanced" models let you adjust water consumption and consumption of coffee powder: from 7 to 11 grams per cup. More simple and cheaper models of espresso makers let you regulate only the amount of water. Strength of coffee then depends only on the amount of servings. You can get a big cup of weak drink or a small, but strong. In some models of espresso makers the regulation is smooth, in others - step by step.