E61: The secret behind the chrome head - Deep Dive

Deep Dive E61: The Secret Behind the Chrome Head

You've decided on a machine with an E61 group head – maybe an ECM, Rocket or Profitec? Then a piece of espresso history is standing in your kitchen. The E61 was developed in 1961 by Ernesto Valente for the Italian manufacturer Faema and fundamentally changed the way espresso is brewed.

But why does this chrome-plated head weigh almost 5 kilos? Why does it take so long to become ready for use? And what exactly happens when you flip the lever? We at Coffee Coaching Club in Bern and Zurich explain the mechanics so you can feel them during your next shot.

Act 1: The preparation – the thermosiphon

Before you even think about coffee, the E61 is already at work. The secret of its legendary temperature stability is the sheer mass of chrome-plated metal – and an ingenious, purely physical circuit.

The group head is connected directly to the hot boiler by two copper pipes:

1. Rising: Hot water rises from the boiler through the upper pipe into the hollow head of the group. Hot water is less dense than cool water – it rises on its own.
2. Heat transfer: In the brew head, the water gives off its heat to the massive brass construction. That takes time – hence the 20 to 30 minute heat-up phase until the entire head reaches operating temperature.
3. Return flow: The slightly cooled water becomes denser and heavier. It sinks back through the lower pipe into the boiler, where it's heated again. This circuit runs continuously as long as the machine is on.

Act 2: The shot begins – the cam controls everything

You flip the lever. What looks from the outside like a simple movement is, on the inside, a precise mechanical interplay. The central component: the eccentric shaft (cam).

The cam is a metal rod with an asymmetric profile – not an even curve, but deliberate lobes. When you turn the lever, this shaft rotates and its lobes press various valves open or closed. A single lever thereby controls the entire water flow: intake, pre-infusion and pressure release.

Interactive: pull the lever, change pressure & temperature, pause/play. Explained in detail in the coffee knowledge article on the E61 group head.

Lever all the way up: the pump starts

1. You flip the lever all the way over. A microswitch behind the lever activates the pump.
2. At the same time, the cam pushes the upper inlet valve open.
3. The hot water from the thermosiphon circuit flows under pump pressure into the middle of the group head – through a small nozzle element (gicleur) that already restricts the flow slightly – and then toward the coffee puck.

Act 3: The heart of it – the mechanical pre-infusion

This is where the taste is decided. It's the reason why E61 espresso has that characteristic soft, full-bodied character.

If the full 9 bar of pump pressure hit the dry coffee grounds immediately, cracks would form in the puck (channeling) – and the espresso would be extracted thin and unevenly. The E61 prevents this with a built-in "soft-start" mechanism that works purely mechanically.

The water's detour:

1. The water doesn't just flow toward the coffee – at the same time it flows into a small, hidden chamber in the lower part of the group head – the pre-infusion chamber.
2. This chamber is sealed off by a spring-loaded valve. As soon as the pressure in the brew head reaches about 1.5 to 4 bar (depending on the spring design), this valve opens and water fills the chamber.
3. This is the key mechanism: As long as this chamber is filling and the spring is providing resistance, pressure builds up on the coffee grounds only slowly. The grounds are gently moistened, swell up and "repair" small unevenness in the puck.
4. Only once the chamber is completely full can the pressure rise to the full 9 bar. The actual extraction under full pressure begins.

All of this happens purely mechanically in the first 4 to 8 seconds of your shot. You can often hear it: the pump works a bit quieter at the start and then audibly "kicks in".

The finale: lever back – pressure release

Your espresso is ready, you flip the lever back.

1. The pump stops (the microswitch triggers).
2. The cam rotates back. The upper inlet valve closes immediately – no new water flows in.
3. At the same time, the cam pushes open the lower outlet valve (pressure release valve).
4. The residual pressure still present in the portafilter above the coffee puck escapes downward into the drip tray. That's the typical hiss you hear.

This means you can remove the portafilter safely right away. The coffee puck is relatively dry – no hot splashing water when you remove the portafilter.

All E61 features at a glance

• Massive brew head made of chrome-plated brass (approx. 4–5 kg)
• Thermosiphon circuit for passive temperature stability
• Mechanical pre-infusion via a spring-loaded chamber
• Cam control: one lever controls all valves
• Pressure release when switching off – clean puck, safe removal
• Purely mechanical system – no electronics in the water path
• Standardized 58mm fitting – compatible with a wide range of accessories
• Proven technology since 1961 (patent by Ernesto Valente, Faema)

E61 group head: technical overview

Who is an E61 machine for?

The E61 is the right tool if you're after the classic, full-bodied espresso. Rounded, viscous, with deep body and chocolatey notes. If you celebrate the ritual – flipping the lever, feeling the mechanical feedback, hearing the hiss of the pressure release. And if you're willing to plan for 20 minutes of heat-up time each morning (or use a timer).

In combination with a high-quality coffee grinder and our roasts like Cozy Chocolate or Nutty Delight the E61 shows its strengths fully: the gentle pressure build-up emphasizes exactly the chocolatey, nutty notes that define these roasts.

Do you need more temperature precision, shorter heat-up times or electronic control? Then take a look at our La Marzocco machines – the GS3 with a saturated group, the Micra and Mini R with an integrated brew group – or the Arkel Coast. A different philosophy, a different result.

Experience E61 machines at Coffee Coaching Club

In our showrooms in Bern (Gerberngasse 44) and Zurich-Oerlikon (Hagenholzstrasse 50b) we are happy to show you E61 machines, for example from ECM, Rocket and Profitec – drop us a quick line at [email protected] before your visit, and we will check which models are currently there. Flip the lever yourself and feel the mechanics. You can test an E61 and a La Marzocco directly side by side in our Espresso Machine and Grinder Comparison. When you buy a coffee machine, our private barista course is included, where we go through extraction and your espresso ritual together – so your first shot lands right away at home. The course is included with any new coffee machine from CHF 1'500, is for up to two people from the same household or company attending together and must take place within one month of delivery – after that, the entitlement expires.

Frequently asked questions about the E61 group head

The massive brass head (4–5 kg) has to reach operating temperature completely. That takes 20 to 30 minutes. The advantage: once hot, the E61 holds the temperature extremely stable – even over several shots in a row. Many owners use a timer so the machine preheats automatically in the morning.

Yes. The mechanical pre-infusion generously forgives small mistakes in tamping and grind size. The gentle pressure build-up compensates for minor unevenness in the puck. That makes the E61 a forgiving platform – especially if you're still fine-tuning your workflow.

A good espresso grinder is essential with any portafilter machine. For E61 machines, we recommend at least a solid single-dose grinder. Depending on budget, the Varia VS4, the Option-O Lagom or a Weber Workshops grinder are ideal partners.

Neither, really – it depends on your priorities. The E61 delivers a softer, rounder espresso with more body and forgives mistakes more generously. The saturated group head offers higher temperature precision and – in our observation – clearer aroma separation. If you'd like to compare both directly side by side in the cup, there's our Espresso Machine and Grinder Comparison for that.

E61 in our shop: You'll find espresso machines with an E61 group head from ECM, Rocket Espresso, Profitec and Bezzera, among others – every type of machine is in the Coffee Machines collection.

Roastery tip

The E61 is practically made for medium to darker roasts. Its gentle pressure build-up emphasizes body, sweetness and chocolate – exactly the strengths of our Cozy Chocolate and Nutty Delight. For nutty depth, Very Nutty is especially impressive on an E61. If you also want to try light, fruity roasts: the E61 can do it, but a machine with a saturated group head will tease out the fine fruit notes even more clearly.