How the E61 Brew Group Works: Thermosiphon, Pre-infusion & 3-Way Valve Explained Simply

The E61 brew group is the mechanical heart of many portafilter espresso machines. Introduced by Faema in 1961, it keeps the brew water at temperature via a thermosiphon without its own heating element, controls three valves via a lever, and automatically pre-infuses the coffee before the full pressure of around 9 bar kicks in.

Move the lever yourself, change pressure and temperature, and observe what happens inside – the animation runs by itself, but you can intervene at any time:

What is the E61 brew group?

The E61 is a brew group developed and patented by Faema founder Carlo Ernesto Valente in 1961. Its name harks back to the total solar eclipse of February 15, 1961 – the year of its market introduction. The Faema E61 was the first espresso machine with automatic pre-infusion, an electric pump, and a thermosiphon for temperature control of the brew group. These three innovations are still defining today. The design became so influential that the E61 group is now installed in countless machines by renowned manufacturers – such as Rocket Espresso, ECM, Bezzera, or Profitec.

The thermosiphon: Temperature without its own heating element

The group itself has no internal heating. Two lines connect it to the boiler or heat exchanger: Hot water rises through the upper line into the group, cools down a bit there, and flows back through the lower line. This natural circulation – the thermosiphon – keeps the heavy, chrome-plated brass group constantly near the brewing temperature. This ensures temperature stability from cup to cup, but requires heating time after switching on, because the large metal mass first has to warm through. The ideal brewing temperature for espresso, depending on the machine and bean, is usually in the range of about 90–96 °C.

Lever, cam, and the three valves

A cam – an oval metal disc that presses on the valves one after another when rotated – is attached to the lever. The lever has three positions:

• Down: Group off – the drain valve is open.
• Middle (rest): both sides are tightly closed – some baristas also use this intermediate position for manual pre-infusion.
• Up: Brewing – water flows to the coffee.

Three valves work together in this process: the brew valve (top), the spring-loaded infusion valve (middle), and the 3-way or relief valve (bottom). The special thing is that the infusion valve is not controlled by the lever, but by the pressure itself – it only opens when a certain pressure is reached.

How a shot runs – step by step

1. You lift the lever: The brew valve opens, the pump fills the pre-infusion chamber above the infusion valve.
2. Pre-infusion: The coffee puck is gently and evenly wetted at low pressure – this reduces channeling.
3. When the pressure reaches about 4–6 bar, the spring-loaded infusion valve opens.
4. The pressure rises to the full brewing pressure of about 9 bar, limited by the expansion valve (OPV). The espresso flows, the crema forms.
5. You lower the lever: The brew valve closes, the 3-way valve releases the residual pressure from the puck into the drip tray – the typical short hiss at the end.

Why baristas appreciate the E61

The E61 combines three strengths: temperature stability due to the thermosiphon, gentle, automatic pre-infusion for more even extraction, and a robust, maintainable mechanism that has proven itself for decades. In addition, there is the tactile lever feel that many love about the espresso ritual. Frankly, the system also has two downsides: The large metal mass requires a certain heating time (often 20–30 minutes for full stability), and the group needs regular maintenance – occasionally grease the cam, replace the brew group gasket when necessary, and backflush after espresso shots.

Matching machines & further articles

Are you wondering which machine suits you? Many prosumer machines with an E61 group are heat exchanger or dual boiler machines. Delve deeper into the topic here:

• E61 Technology in Detail: The Secret Behind the Chrome Head
• Single Boiler, Heat Exchanger & Dual Boiler – How the Heating System Affects Your Espresso
• E61 vs. Saturated Brew Group in Comparison
• Brew Group Technology Overview (E61, Saturated, Hybrids)
• Discover Heat Exchanger Espresso Machines with E61 Group
• Discover Dual Boiler Espresso Machines
• All Interactive Coffee Tools & Simulators at a Glance

Frequently Asked Questions about the E61 Brew Group

What does "E61" mean?

The "E" stands for the eclipse, and the "61" for the year 1961 – the total solar eclipse of February 15, 1961, the year Faema introduced the machine.

Does every E61 have a pre-infusion function?

Automatic pre-infusion is constructively integrated into the classic E61 group: Water first fills the pre-infusion chamber and wets the puck before the spring-loaded infusion valve opens at around 4–6 bar. The extent of the pre-infusion depends on the machine and water pressure.

How hot does an E61 brew?

The group itself does not heat, but is kept near the boiler or heat exchanger temperature via the thermosiphon. Typical brewing temperatures, depending on the machine and recipe, are usually around 90–96 °C. For heat exchanger machines, a short blank shot ("flush") equalizes the temperature before the shot.

How do I maintain an E61 group?

Regularly backflush, replace the brew group gasket if it becomes leaky, and occasionally lubricate the lever cam with food-safe grease to keep it moving smoothly.

Which machines have an E61 group?

Many prosumer machines, including those from Rocket Espresso, ECM, Bezzera, Profitec, and other manufacturers. The E61 has developed into a de facto standard over the decades. Browse our heat exchanger and dual boiler machines.

Source

Primary source (inventor/manufacturer): the original patent for the E61 brew group – US Patent 3,230,974 "Alternately seating valves" (inventor Ernesto Valente, Faema; filed 1961, granted 1966).