How the E61 Brew Group Works: Thermosiphon, Pre-infusion & 3-Way Valve Explained Simply
By Yalcin Akpinar · Food chemist, over 15 years in the flavour industry
The E61 group head is the mechanical heart of many portafilter espresso machines. Introduced by Faema in 1961, it keeps the brew water at temperature via a thermosyphon without a heating element of its own, controls three valves via a lever and pre-infuses the coffee mechanically before the full pressure of usually around 9 bar sets in.
Pull the lever, set the pre-infusion spring and the pump pressure – and watch the water find its way. The animation runs by itself, you can step in at any time:
The sliders: pump pressure in bar (6–12) and the pressure in bar at which the pre-infusion spring gives way (2–6). The results: pressure, times and cup are model values, not a measurement of your machine. The basis: patent and functional descriptions of the E61 (sources in the figure); «4 bar» is a community figure, «9 bar» a convention. No guarantee – details right underneath the figure.
The interactive E61 animation is loading … If nothing appears, please reload the page – or simply read on, the text explains everything step by step.
How to read the animation: Red dots are hot water, blue dots cooled water – the arrows show the direction. On the left the boiler, on the right the chrome head with the lever. Lever in the middle: only the thermosyphon runs. Lever up: water fills the pre-infusion chamber, wets the coffee gently, then the spring gives way and the full pressure arrives. Lever down: the residual pressure hisses into the drip tray. The numbers on the gauge are model values, not a measurement.
The animation is a simplified model and shows you how things relate – no measured values and no assurance. Which temperature, which pressure and which pre-infusion end up in your cup depends on your machine, your water, your beans and the way you work.
Our care and setting tips are based on experience from consultations, courses and the showroom. They are non-binding and come with no guarantee. We accept no liability for damage arising from their use. When in doubt, what your manufacturer writes in the user manual applies.
What is the E61 group head?
The E61 is a group head developed and patented by Faema founder Carlo Ernesto Valente (priority application in Italy 1960, US patent granted 1966). Its name goes back to the total solar eclipse of 15 February 1961 – the year of its market launch. The Faema E61 is considered the first espresso machine with an electric pump, a thermosyphon for controlling the temperature of the group head and automatic pre-infusion. These three innovations still define the field today. The design became so influential that the E61 group is built into countless machines by renowned manufacturers today – for example Rocket Espresso, ECM, Bezzera, Profitec, Lelit or Torre.
The thermosyphon: temperature without a heating element of its own
The group itself has no heater of its own. Two lines connect it to the boiler or heat exchanger: hot water is lighter than cooler water and rises through the upper line into the group, gives off heat to the brass there and flows back through the lower line. This natural circulation – the thermosyphon – runs as long as the machine is heating and keeps the heavy, chrome-plated brass group close to brew temperature. That makes for temperature stability from cup to cup, but costs heat-up time after switching on, because the large metal mass has to warm through first. Usual brew temperatures for espresso are around 90–96 °C depending on machine and bean – a guide value to start from, not a rule. Guide valueWhich temperature you like is decided by your cup.
Lever, cam and the three valves
On the lever sits a cam – an oval metal disc that presses on the valves one after another as it turns. The lever has three positions:
- Down: group off – the brew valve is closed, the release valve is open. Residual pressure escapes into the drip tray, the portafilter can be removed safely.
- Middle: The release valve closes, the brew valve opens only a crack – the pump is not running yet. Water reaches the coffee only with the pressure from the boiler or the mains. Some use this intermediate position for a manual, particularly gentle pre-infusion.
- Up: brewing – the cam opens the brew valve fully and switches the pump on via a microswitch.
Three valves work together here: the brew valve (top), the spring-loaded infusion valve (middle, we call it the pre-infusion spring here) and the three-way or release valve (bottom). The special thing: the infusion valve is controlled not by the lever but by the pressure itself – it only opens once a certain pressure is reached.
How a shot runs – step by step
- You lift the lever: the brew valve opens, the pump fills the pre-infusion chamber above the infusion valve.
- Pre-infusion: the coffee puck is wetted gently and evenly at low pressure – that reduces channelling.
- Once the pressure reaches around 4 bar, the spring-loaded infusion valve opens. CommunityThe value comes from the Home-Barista community and depends on spring and machine – we have not measured it ourselves.
- The pressure rises to full brew pressure, limited by the expansion valve (OPV). Convention«Around 9 bar» is the usual specification of manufacturers and of the Istituto Nazionale Espresso Italiano (9 ± 1 bar) – a convention, not a measurement of your machine. The espresso flows, the crema forms.
- You lower the lever: the brew valve closes, the three-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 through the thermosyphon, gentle, automatic pre-infusion for a more even extraction and a robust, serviceable mechanism proven over decades. Add to that the tactile feel of the lever that many love about the espresso ritual. Honestly, the system also has two downsides: the large metal mass needs a certain heat-up time (often 20–30 minutes for full stability – experience value, not a measurement), and the group wants regular care – grease the cam occasionally, replace the group gasket when needed and backflush after espresso shots. Our taste impression from roastery and showroom: lots of body, full mouthfeel. For us, a saturated group head brings aroma and elegance on top – our view, one of many. If you like it, you're right.
Matching machines & further reading
Wondering which machine suits you? Many prosumer machines with an E61 group are heat exchangers or dual boilers. The fastest way to find yours is with Jackson, our AI advisor, or in the machine finder. Go deeper here:
- E61 technology in detail: the secret behind the chrome head
- Single boiler, heat exchanger & dual boiler – how the heating system influences your espresso
- E61 vs. saturated group head compared
- Group head technology at a glance (E61, saturated, hybrids)
- Discover heat-exchanger espresso machines with E61 group
- Discover dual boiler espresso machines
- All interactive Coffee Tools & simulators at a glance
E61 in our shop: You will find espresso machines with an E61 group head from ECM, Rocket Espresso, Profitec, Lelit, Torre and Bezzera, among others – all designs in the collection Coffee machines. All of it you can order online; in Bern and Zurich many of them stand set up and running – seeing them live is the reason you can do that without a knot in your stomach.
Frequently asked questions about the E61 group head
What does „E61“ mean?
The „E“ stands for the solar eclipse, the „61“ for the year 1961 – the total solar eclipse of 15 February 1961, in whose year Faema presented the machine.
Does every E61 have pre-infusion?
Mechanical pre-infusion is built into the design of 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 bar (community figure, varies by machine). How pronounced the pre-infusion turns out depends on the particular machine and on the water pressure.
How hot does an E61 brew?
The group itself does not heat; it is kept close to boiler or heat-exchanger temperature via the thermosyphon. Usual brew temperatures are around 90–96 °C depending on machine and recipe (guide value). On heat-exchanger machines a short flush („cooling flush“) evens out the temperature before the shot.
How do I care for an E61 group?
Backflush regularly, replace the group gasket when it stops sealing well and occasionally lubricate the lever cam with food-grade grease so it stays smooth. What counts is your manufacturer's manual.
Which machines have an E61 group?
A great many prosumer machines, including those from Rocket Espresso, ECM, Bezzera, Profitec, Lelit, Torre and other manufacturers. Over the decades the E61 has become a de facto standard. Browse our heat-exchanger and dual boiler machines.
Sources
Primary source (inventor/manufacturer): the original patent of the E61 group head – US patent 3’230’974 „Alternately seating valves“ (inventor Ernesto Valente, Faema; Italian priority 24.9.1960, US application 25.9.1961, granted 25.1.1966; accessed 16.10.2026). Function and lever positions: Kaffeemacher, «Faema E61 Brühgruppe» (accessed 16.10.2026). Opening pressure of the pre-infusion spring (around 4 bar, community figure): Home-Barista, «Internals of an E61 Brew Head» (accessed 16.10.2026). Cooling flush on heat-exchanger machines: Home-Barista, «HX Love: Managing HX Brew Temperature» (accessed 16.10.2026).
Yalcin Akpinar
Co-founder, equipment and sensory
Graduate food chemist from the University of Hamburg, over 15 years in the international flavour industry, patents in flavour technology. With us he is responsible for roast profiles, bean selection and the choice of machines and grinders.
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