How do espresso machines work?

You’ve been eyeing a few for a while, and now you are ready to buy one gorgeous Bellman espresso maker for your home.

This guide will show you how to use a semi-automatic espresso maker so that you can take your machine home with confidence.

Let’s first look at the key terms that you need to understand when discussing espresso machines.

Dialing – This is coffee jargon that allows you to adjust certain parameters during the brewing process. This could include adjusting the grind size, tamp, or quantity of espresso.

Portafilter- The portafilter is the place where you put your ground coffee. It is exactly what the name implies – a filter. The portafilter is used to make espresso. It allows water to flow through at the perfect pressure and temperature for it to produce a rich, decadent cup of espresso.

Tamp is the act of compressing the coffee in the portafilter to prevent water from rushing through the grounds. A good tamp prevents water channeling and creates more solids.

Bars Of Pressure – A “bar” is the unit of measurement that indicates the pressure at which your coffee was extracted. The rule of thumb is that espresso should be extracted at 9 bar pressure. This is 130 PSI or more than four times the pressure of a car tire.

Let’s now talk the language and take a look at what the various parts of your espresso machine are.

Water And Pump

Espresso is not possible without water. An espresso machine uses water from either a small reservoir that is filled with water or a connected water line. There are home espresso machines that use either.

How do we get the water through the espresso maker? This is where the pump comes in. A pump is required to make espresso at the correct pressure.

Espresso is a well-known name. Nine bars is the ideal pressure to extract the best espresso.

There are two types of pumps. There are two main types of pumps: rotary and vibration pumps. The most common use of rotary pumps is in commercial machines. They provide constant pressure and are used more often. You will find vibration pumps in your home espresso machine. They only produce pressure when you pull an espresso shot. You might not notice any difference unless you are geeky. However, vibratory pumps tend to be louder.


The boilers are one of the most important features you should be looking at. Espresso, like all coffees, requires that water is at the right temperature to extract it properly. Your boiler is what will get it there. A one-way valve allows water to be fed into the boiler, where it is heated and collected.

Semi-automatic espresso machines can use one, two, or three types of boilers.

Boiler With Single Boiler

One boiler is exactly as it sounds. One tank holds water for both steaming milk and brewing espresso.

A single boiler means that you can’t brew espresso simultaneously with the steam wand. Two temperatures are ideal for steaming milk and one for making espresso. You will need to wait for each function to finish before you can use the next. It can be a hassle when you are trying to make a latte. Your espresso will start getting cold while you wait for the milk to steam.

Single boilers can be found only in semi-automatic and low-end automated espresso machines.

Heat Exchange

A heat exchange boiler can be described as a large boiler. However, it also has an isolated section that is separate from the main heating element. A heat exchanger’s isolated section provides water that is more chilled and is suitable for brewing. This is done by continually supplying water through an isolated element into the group head and back into the machine.

You don’t need to wait as long to use your steam wand or pull an espresso shot with your single boiler.

Double Boiler

A dual boiler is similar to a single boiler. It is also very well named. Dual boiler espresso machines have two separate tanks, rather than one that does all of the work. One tank heats water to brew while the other heats it for steaming.

Dual boilers allow you to steam milk and brew simultaneously without waiting for the water temperature change. You can steam milk simultaneously and brew it simultaneously with the two separate boilers. The best option for temperature stability is the dual boiler because each tank can be kept at the right water temperature.

A dual boiler is ideal if you need to steam milk while also pulling a shot.

Group Head

This is where the magic happens. The group head is located on the front of the espresso machine and locks the portafilter in place.

The valve seats are opened when you pull an espresso shot. The group head then sends pressurized hot water from the espresso machine through your coffee and out the bottom of your portafilter, creating espresso.

There may be one or two group options when buying an espresso machine. This simply tells you how many parts you can use to make espresso. You will likely only need one group head for your home setup.

Last Thoughts

This is it. This is how the espresso machine works. Although it sounds easy to run hot water through compact coffee beans, many things are going on inside these tiny machines.