Different Types of Group Heads : What Are They?

While there may be a lot of complicated parts to the espresso machine, the group head is one that is commonly talked about. It is the centerpiece of any espresso machine, mostly positioned at the center front of your espresso machine. That being said, what is a group head? What does it do, and how many types of group head are there?

In this article, we'll explain all about the group head and the different types without getting too technical. By the time you're finished reading, you will know how a group head works, the importance of a group head, and which one suits the best for you.

What is a group head?

E61 group head on the Rocket Appartamento.

The group head is the part of the machine that dispenses pressurized hot water. You know, the one where you lock your portafilter in so you can pull beautiful espresso shots. The group head is where the water meets your coffee, turning it into espresso.

It is where the magic happens.

The group head ensures thermal stability for your brew water temperature. If your water temperature is too low, your espresso might turn out sour, and if it gets too high, it might taste burnt or bitter. It also ensures the high pressure is safely channeled to your coffee within the group head chamber.

Group head ticks all the boxes to ensure that you can pull espresso correctly, safely, and deliciously.

What are the different types of group head?

There are too many different types of group heads out there, so it is not that straightforward to classify them into simple categories. Some may share the same name but with a slightly different mechanism, while some have different designs but works the same.

However, we have compiled the main types of group heads that are widely used by prosumers and baristas all over the globe.

The five main types of group heads are :

1. Electrically Heated

2. Conventional

3. Lever

4. E61

5. Saturated

Electrically Heated Group Head

First off, we have the electrically heated group head. As the name suggests, the group head is electrically heated with heating elements and is usually controlled by a thermostat, or PID. The heating elements are embedded in the group head and helps maintain thermal stability.

The electrically heated group head on Stone features a coiled heating element to achieve faster heat up time.

Electrically heated group head machines tend to be popular among entry-level machines, as it is fairly cheap to produce. It is also the fastest group head to achieve brewing temperature upon turning on when compared to the other group heads, making it ideal for home use.

Some examples of electrically heated group head machines are Stone (ready in just 10 minutes) and Profitec Pro 300.

Conventional Group Head

Nuova Simonelli Music features a conventional group head.

Conventional group heads are pretty much, conventional. It is a no sweat group head that is quite straightforward to brew espresso. It uses a 3 way solenoid valve to relieve excess pressure after brewing, and is not heated. The design is usually quite simple too. While it may not be the best group head for thermal stability, it is a proven tech with simple construction, and is cheaper to produce than other group heads.

There are also a great deal of conventional group heads out there with different designs and different technology, namely Rocket Boxer, Nuova Simonelli Musica, and Rancilio Silvia V6.

Lever Group Head

The term "pulling" a shot was based on, well, literally pulling a lever for an espresso shot. It was developed by Gaggia in 1945, designed to increase brewing pressure than the steam-driven machines that were popular prior.

There are two types of lever group heads; spring piston and manual piston. With the manual piston, you are pushing the water through the coffee ground to brew. When you pull the lever for the spring group head, you are compressing the spring piston in the group head, creating pressure. As you release the lever, the spring slowly decompresses as it brews your espresso.

The Leva by La Marzocco features spring piston and is equipped with numerous modern features such as a clutch and also a drain hole for excess water/pressure.

It can be a "jaw breaker" if you are not careful enough when handling it (the lever will be pushed up if you pull it with no coffee ground as resistance), so practice safe workflow at all times. Some levers do not have a "exhaust" to relieve the excess water and pressure too, so you'll have to leave the portafilter on for 10-20 seconds before you can take it out.

That being said, the spring lever delivers beautiful espresso as it pulls a direct 9 bar (assuming the spring is pre-calibrated) and gradually decreases over time (you can call it the traditional pressure profiling), while the manual piston gives you full control of the pressure during brew.

The hot water hits the coffee at a lower pressure for pre-infusion, then the brew pressure increases to start, before gradually decreasing over the shot extraction. The water that hits the coffee is on 100% contact consistently and evenly throughout the entire process.

While it may not be practical in today's fast-paced industry, it's hard to deny the beauty and versatility of a lever machine. The Pro 800 by Profitec and Leva by La Marzocco are some of the best lever machines we can recommend. If you're into manual lever, why not give the Robot Barista by Cafelat a try.

Saturated Group Head

A saturated group head is one that is surrounded in water from the boiler. Instead of a completely separate component, the group head acts as an extension of the coffee boiler, allowing for consistent water temperature throughout. Many machines use tubing to route the flow of water outside and around the group head, which can rapidly change and maintain the temperature.

Cross section of a saturated group head. The gooseneck is welded directly on the boiler, and gets water directly from it. Water in the boiler also circulates around the group head, resulting in excellent thermal stability.

La Marzocco first introduced the saturated group head through the GS machine in 1970. Saturated group heads draw water from directly inside the boiler, which translates to stable brew temperatures, every time. It is popular among commercial machines as it features excellent thermal stability, is reliable, and heats up in no time. On the contrary, the parts are not easy to source, and saturated group heads tend to be on the pricey side when it comes to maintenance.

A bulk of La Marzocco machines such as the GB5, Linea Classic, and GS3 feature saturated group heads. Other brands that also use saturated group heads include Slayer, Synesso, and Kees van der Westen.

E61 Group Head

You can recognize an E61 group head from a mile away just from the classic design of the sleek, lump of brass protruding out from the machine.

Cross section of an E61 group head. The moving mechanical parts of an E61 not only allows for superior thermal stability, but also manual pre-infusion.

It was invented in 1961 by Faema (hence, the name E61). It revolutionized how quickly and efficiently coffee could be prepared, and it set a new standard for quality that other brands followed.

E61 retains heat longer and better than any other group heads through its chrome plated brass, using the concept of thermosyphon. It takes a longer time for an E61 to achieve brewing temperature too, but also longer time to dissipate heat which is actually important for thermal stability.

61 years after its inception, the E61 is still being used today and can be dubbed an oldie but a goodie. E61 group head features superior thermal stability, is easy to dismantle and fix, and spare parts are widely available. In contrast, it takes about 15 minutes or longer to heat up an E61, and it can be susceptible to wear and tear due to the many moving mechanical parts.

The Rocket Appartamento is an iconic E61 machine, followed by ECM Classika, Profitec Pro 400, and Lelit Bianca.

Considering you know the basics of an espresso machine, you can now make informed choices when selecting the type of group head of your espresso machine.

The E61 may be slow at warming up when you turn on your machine, but it is still popular even among home users due to its reliability and stability (and it looks good too).

The saturated group head is the preferred choice for high-volume cafes due to its heavy duty features, and solid thermal stability.

Are you a purist? You don't mind to literally "pull" an espresso shot? If you wish to enjoy espresso like how it was done back in the days, the lever delivers delightful espresso, manual or piston. Plus, we think "pulling" the lever looks really cool too.

If you are a no fuss coffee drinker, and wish for a machine with a group head that is practical and works just fine, the conventional or electrically heated group head could be the one for you.

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