How Does An Espresso Machine work?

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How does an espresso machine works

Have you seen a barista working so efficiently on the espresso machine? Millions of people across the earth are using an espresso machine without any hiccups. However, very few of them actually know the science as to how does an espresso machine work

Now that you wish to have an exquisite espresso coffee maker at your home and amaze your guests, you are bound to know about the parts and the mechanism. 

When you urge to learn about the working mechanism of the espresso machine, you will find certain words. These related words are impenetrable for instance, 9 bars of pressure or portafilter. Therefore, each of these words is an important key term to understand as to how espresso machine works.

So, let us first see the key terms that as generally used for espresso machines.

Key Terms to Understand How Espresso Machine Works

  1. The Water and Pump – The pump is going to provide the required amount of water for coffee.
  2. The Boiler – As the name mentions, it the container to heat the water for coffee and steam.
  3. The Portafilter – The portafilter is the place where you keep the ground coffee. Consequently, water from the boiler reaches the portafilter, and under ideal temperature and pressure coffee is decanted to form an espresso.
  4. The Bars of Pressure – This is the measure of pressure, that we use to extract a perfect espresso. According to experts, the exact pressure for an espresso is 9-bars which is equal to 130 PSI. However, this is amazing to know that we use this amount of pressure in air pump for car and bike! It is indeed high pressure.
  5. A Flat Tamp – A flat tamp helps to limit the amount of water in the channel. Furthermore, it does not allow the water to flow into the ground in the portafilter easily. Therefore, it facilitates dissolving more solids.
  6. The Dialing In – Last but not least, is the process of dialing in. In fact, it is the very first step that a barista performs. It is the expertise to use the right amount of coffee, water, and brewing time to get the best espresso coffee in the cup.
commercial espresso machine brewing coffee

Now, let us have a look into every component of the espresso machine precisely to understand how each part functions in the overall functioning of an espresso maker.

The Water Source 

Although we all know that without water, we cannot make espresso coffee, we do not know the source of it. For the espresso machines we use at home, there are two sources of water – Either it has a reservoir to store the water or it has a consistent tap water supply system.

The espresso machines are crafted based on the water source. For example, if it is a home espresso machine for making low-quantity but high-quality coffees, it will have a reservoir attached to it. The perk of a fitted reservoir is that you can effortlessly dial in high-quality water and there is no space for apprehension about the water quality. This actually happens in the areas where you do not have a good tap water source and use separate water for cooking and drinking purposes.

However, for larger machines, especially commercial ones, you cannot depend upon a reservoir for dialing in purpose. The reason is, you have to supply hundreds and thousands of excellent espresso to the customers. So, there should be a constant supply of water to the machine. There is no reason to worry about the water quality because most of these machines come with in-built water softening and filtration system. Hence, whatever the source may be, water is always perfect for the coffee grounds.

Lastly, there are these hybrid machines that are complex and have both systems. On one hand, they have the reservoir and on the other, they have a direct plumbing option for water supply.

The Pump

As our body requires the pumping of blood through the heart to survive, the pump of the espresso machine is the heart of it. The reason is, it is that part of the machine that gives that exact 9 bars of pressure to make the appropriate espresso coffee. In other words, it gives water the power and strength to drive itself through the firmly packed bed of ground coffee.

The traditional espresso machines had manual pumps and the barista had to pull the levers forcefully to send the water to the bed of coffee. However, the modern ones are automatic with two types of pumps- the vibratory pump and the rotary pump.

A Vibratory Pump for Espresso Machine

The vibratory pumps are present in the home espresso machines specifically while the rotary pumps are found in commercial machines. Nevertheless, the main difference in these pumps lies in the working mechanism. On one hand, the rotary pump is mechanical and provides a constant supply of pressure. On the other hand, the vibratory pumps are electromagnets and work only when there is a need for an espresso shot.

a rotary pump for espresso machine

Unless you are a gadget-geek, the only difference you will notice is the sound. Vibratory pumps produce noise while the rotary ones do not make a sound. Moreover, the vibratory pumps are smaller, easy to replace, and less costly compared to rotary pumps.

However, there is no difference in taste or quality of the espresso coffee. Both the pumps produce equally elegant coffee.

The Boiler

Just like coffee beans, the temperature of the water in the espresso must be optimum and perfect. The boiler in the machine is going to do this work for you.

There are mainly two types of boilers in an espresso machine: the single boiler and the double boiler.

Single Boiler

In a single boiler, as the name sounds, it collects water and heats it in a single tank. Moreover, the water used is for both brewing coffee and steaming the milk. The cons of the single boiler are that it cannot be used simultaneously for brewing and steaming. As a matter of fact, the temperature for brewing and steaming are poles apart and so, you have to wait for one process to end and then start another one.

Single boilers are generally found in cheaper machines that may be automatic or semi-automatic ones.

Double Boiler

Double boiling systems have two different tanks for brewing and steaming. Hence, you do not have to wait for the temperature change. Both the functions occur simultaneously. Moreover, the temperature stability in both the tanks is worth mentioning. 

Therefore, if you are willing to pull an espresso shot and steam milk, a double boiler is the most appropriate option for you.

The Steam Wand 

In recent days, milk-based coffees like, lattes are in demand. Some of us cannot even think of a coffee without milk. Therefore, if you make a latte, steaming of milk is essential. The steam wand helps to steam the milk and make the froth for cappuccinos and lattes.  

However, not every espresso machine comes with a steam wand. But with technology, most of the manufacturers now provide the steam wand to let you prepare specialty milk-based drinks at home.

a steam wand in use

As we have discussed earlier, the boiler helps in heating the water in the espresso machines. Moreover, the water should not rise above the optimum temperature. Otherwise, the espresso will lose its ecstasy. The ideal temperature is around 85-95 degrees Celsius. This temperature is below the actual boiling point of water and hence, it is impossible to generate steam from it.

Nevertheless, there is a way to recompense for a steam wand. You can use an additional boiler exclusively for steaming the milk.

The Grouphead

A Grouphead is the last part where the coffee reaches before it is in your cup. This part helps the pressurized water to reach the bed of coffee grounds. Several small parts make up the group head. Hot water comes out from the exterior part. This part is locked with the portafilter and we often misinterpret this part as the group head. 

However, though this is one function of the group head, it has other functions too. For instance, certain companies modify the Grouphead to function as pre-fusion. Moreover, various machines have various forms of group heads. They may not match each other.

Nearly all general types of Group-head works as a separate unit from the boiler. Just as the water from the boiler starts heating, the interior-most part of the Group-head also starts heating. The most vital thing to note is that the machine has to maintain the required temperature. Therefore, the Grouphead is always hot; it is neither cold nor warm.

Consequently, when the Grouphead gains the appropriate temperature, it conveys a signal to the boiler and the espresso machine can initiate a shot.

grouphead of espresso machine

Saturated Grouphead

The saturated Grouphead is one such Grouphead that is worth mentioning. This is expensive but faster in the heating process. The inner part of the Grouphead has a direct connection to the boiler. Therefore, it is saturated or heated up faster than other forms.

Semi-saturated Grouphead

The semi-saturated Grouphead, on the other hand, is attached to the boiler with the help of a heat exchanger. These groupheads are less expensive and are repaired easily. However, since it is not in direct contact with the boiler, the process of heaating is long and it takes time to reach the required temperature.

The Portafilter

The portafilter is technically a part of the Grouphead. However, it is indeed the representative of an espresso machine. Think of a barista and you can visualize one with a portafilter in his hand. In fact, a group head is a complete tool only when you attach the portafilter to it.

So, what is a portafilter? It is the compressed form of the words portable filter, which means you can carry the ground coffee in these filter baskets and are easy to move. The size of portafilters varies. However, there are some standard sizes for espresso machines. The two most common sizes are 53mm and 58mm. Most commercial espresso machines have 58mm portafilter, though both of them produce coffee of the same taste and flavor. Sometimes, an insulating material encloses the handles of portafilters so that you can save your hand from burning. Overall, a portafilter comprises two main things- the coffee carrying basket and the handle to carry.


So, How Does An Espresso Machine Works

We thought to provide a visual aid on the process as it exactly tells you how the whole espresso machine works and how each part functions in connection. Here is the video by WholeLatteLove:

The End Note

Yes, it is a brainstorming session to understand how does an espresso machine works? However, the question may arise as that why the experts made such a machine? Why can we not use a simple stovetop coffee percolator?

According to experts, you cannot expect high-quality, mesmerizing beverages from the stovetop. These physics of espresso machine is helping the population to get the actual taste of the coffee grounds. Moreover, a good espresso machine will bring to you more cups of coffee instantly than any other coffee-making machine.

Therefore, knowing the parts of an espresso machine and its working mechanism is indeed helpful. Above all, if you are willing to buy one, hopefully, this article is going to give you enough confidence.