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20 Questions You Should Always Be Asking About Machine Espresso Before Buying It
How Does Machine Espresso Work?

The machine espresso is made using precision pressure, and a filter technology that is awe-inspiring to create the coffee you enjoy. How exactly does it work?

Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee. However, the pressure is the major difference.

The Group Head

As the name implies the group head is where you place your portafilter while brewing espresso. It disperses the water into the portafilter, and regulates the pressure of extraction. There are numerous kinds of group heads each with their own advantages and disadvantages. Some are specifically designed for stability of temperature while others are designed to handle pre-infusion. Others are made to control the lever. There are even some that include a mix of features, like the E61 one, which is the standard choice for many baristas due to its ability to offer multiple benefits in a single package.

As you can see in the picture above the group head is equipped with several notches. You place your portafilter in these notches, then turn the head around to secure it. There is also a rubber gasket that resides inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is vital to ensure an efficient extraction.

In addition to allowing you to easily insert your portafilter, the group head is responsible for maintaining an even temperature. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it's always at the correct temperature for extraction. It is important to realize that even a slight difference can make the difference between a great and a great espresso.

The Pump

Motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines that rely on a lever. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps are generally more affordable and last longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and insufficient cleaning. Pumps are also more complex mechanically, and can add to the cost of even the most basic models.

Some espresso machines do away with the pump completely and employ steam pressure to create espresso. This can lead to over-extraction as the boiler that makes steam also heats the water to boil. Additionally the machines often have to rebuild their pressure between cups, which requires time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model employs an oscillating disk to create pressure, while a rotary model pushes hot water through the ground at a high speed. Both types of machine can make excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the one that is used to heat the water to the right temperature to extract. The steam that is produced will eventually reach the portafilter, which is a container for espresso grounds. It is then poured into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This produces a layer of crema on top. This is one of the main characteristics of a great espresso.

There are espresso coffee machine home of espresso machines, each having a different type of pump and the temperature of the brew. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-based. They employed one boiler to make both steam and brew however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.


The most popular espresso machine is a semiautomatic that has an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself The pump, however, regulates the water flow and pressure. This is an excellent compromise between human touch and the mechanized quality.

The Filter

Espresso machines typically have filters that separate the grounds of the coffee from the hot water. The filter is also a crucial part of the temperature control system since it helps prevent the machine from overheating.

Filters also aid in flavor since it allows for a longer flowering phase. This lets the beans release their nuances, and also allows for better extraction.

However, it is important to remember that even a high-quality filter could result in a bad cup of coffee, because the quality of the beans and extraction is vital.

This is where the magic happens. It's what makes espresso taste great. The grouphead, also called the brewhead, is where the portafilter (the device you put the ground coffee in) is placed when you're making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight vessel to create steam. The steam then moves hot water through the coffee grounds under high pressure. These kinds of machines are typically less expensive and easier to maintain than pump-driven models. However, they are limited in their ability to create the ideal brewing conditions, since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

In recent years, compressed air pump-driven espresso machines have been gaining popularity. They use an air-compressor to force hot water through the ground and are much more mobile than steam-driven electric espresso machines.

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