The E61 brew group is featured in more espresso machines than any other technology. ECM, Rocket, Lelit, Profitec, Quick Mill, Bezzera—they all build on a design invented by Ernesto Valente in 1961. More than 60 years old and still the top choice for hundreds of manufacturers worldwide. We explain how the thermosiphon principle works, why mechanical pre-infusion still hasn't been beaten by any electronic system, and what you need to know about maintenance and care so that your E61 machine will still work perfectly in twenty years' time.
1961: Ernesto Valente and the total solar eclipse
Before the E61, espresso was a physical labor. The manual lever method by Achille Gaggia, introduced in 1947, generated the necessary 9 bar pressure via a strong spring that the barista had to tension by hand. It was exhausting, the pressure curve was fixed by the spring characteristics, and the temperature often remained inconsistent. This technology was too demanding for the mass market.
Ernesto Valente, founder of FAEMA (Fabbrica Apparecchiature Elettromeccaniche e Affini), thought bigger. He wanted to automate and standardize espresso: not as a niche product for specialized operators, but as a reproducible result, independent of the strength behind the lever. In 1960, Valente filed the patent for a system of "alternating closing valves." One year later, the machine was ready for the market.
Valente chose the name E61 in honor of the total solar eclipse (eclisse in Italian) that was visible in Italy in 1961. A romantic name for a very sober engineering feat: constant pump pressure of 9 bar, a passive keeping-warm system, and mechanical pre-infusion. Three innovations in one machine that permanently changed the espresso world.
The thermosiphon principle: Ingeniously simple, physically elegant
The heart of every E61 machine is the thermosiphon. It is so simple that you might not understand it at first. No extra pump, no extra heating element in the group, no electronics. Just two copper pipes and the physics of heat transfer.
Here is how it works: The brew head is connected to the heat exchanger or boiler via an upper and a lower pipe. Hot water has a lower density than cold water, so it rises. Hot water from the boiler flows through the upper pipe into the chambers of the massive brew head, transfers its heat to the brass, cools slightly, and sinks back into the boiler through the lower pipe. This cycle runs continuously as long as the machine is heated, even when no espresso is being drawn.
The result is a brew group that is always at temperature. No active heating required, no separate sensor, no control unit.
The brew head of an E61 machine is made of chrome-plated brass and typically weighs over four kilograms. This massive amount of material must first be brought to operating temperature by the circulating water, which takes 20 to 30 minutes. If you turn on the machine sooner and pull an espresso immediately, you will encounter a brew head that has not yet fully heated up. The extraction will be too cold, and the espresso too sour. Buy a timer and let the machine preheat.
The downside of thermal mass: During longer periods of inactivity, the water in the thermosiphon overheats. If you want to pull an espresso after a half-hour break, you should flush it for two to three seconds first. The overheated water needs to be cleared out before the portafilter is inserted. The exiting water should no longer steam or sputter. The overheating problem is more pronounced with heat exchanger machines than with dual boilers.
Mechanical pre-infusion: Three positions that change everything
The second great invention by Valente is the integrated, mechanical pre-infusion. And in our eyes, it is the most ingenious part of the entire design because it functions without any electronics and still works every single time.
The E61's side lever has three functional positions:
Rest position: The inlet valve is closed. The release valve is open, allowing residual pressure to escape from the group. The coffee puck remains dry, and the portafilter can be easily removed after extraction.
Pre-infusion (middle position): The inlet valve opens slightly, and the release valve closes. On machines with a direct water connection, water now flows onto the coffee at line pressure only. The puck begins to swell slowly and wet evenly, still without full extraction pressure.
Extraction (upper position): The cam fully opens the inlet valve and simultaneously activates a microswitch that starts the pump. But even now, the pressure does not jump immediately to 9 bar. A small expansion chamber in the brew head (about 8 to 10 milliliters in volume) fills up first, delaying the pressure buildup. Only when this chamber is full does the water hit the puck at full pressure.
The result is a soft, natural pressure curve. The coffee has time to settle and saturate evenly before full extraction pressure hits. Channeling is reduced, and the extraction is more uniform. Without a single line of code.
Modern machines can electronically control the pump and thus follow any pressure profiles. The E61 pre-infusion is more limited but more robust: no risk of software bugs and no calibration required. If you just want good espresso without worrying about profiles, the mechanical E61 solution is perfect for you. If you want to experiment and adjust profiles, you need more. More on that below.
Flow Control: The E61 in the 21st century
The E61 is 60 years old, but it hasn't stood still. The latest innovation brings proven mechanics right to the cutting edge of espresso preparation: Flow Control.
The principle is simple. Instead of the fixed gicleur (a small nozzle that limits maximum water flow), a needle valve is installed. This allows the barista to manually change the cross-section of the water supply during extraction. A long, low-pressure pre-infusion? Possible. Dropping pressure at the end of the shot? That works too.
This is particularly interesting for light roasts. Light roasts often require longer extraction times and specific pressure curves to unfold their complex acidity structure without excessive bitterness. Machines like the Lelit Bianca V3 or the ECM Synchronika II offer this feature as standard. A mechanism over 60 years old as a platform for state-of-the-art extraction technology. That’s actually quite cheeky.
Brew group types compared
The E61 is one of three fundamental brew group types, which differ based on how much water contact the group has in its resting state. This determines almost everything: heat-up time, thermal stability, price, and maintenance effort.
| Feature | Unsaturated group | E61 thermosiphon group | Saturated group |
|---|---|---|---|
| Water contact when resting | None | Circulating, passive | Permanent, directly at the boiler |
| Heating principle | Flow-through only during extraction | Passive thermosiphon cycle | Group welded directly to boiler |
| Thermal mass | Low | High (4+ kg brass) | Very high (group plus boiler water) |
| Heat-up time | 1–5 minutes | 20–30 minutes | 15–25 minutes |
| Thermal stability | Low, first shot often cold | Very high after full heat-up | Very high, stabilized by boiler water |
| Mechanical pre-infusion | No | Yes, integrated via lever | Mostly electronically controllable |
| Additional heating element possible | Rarely | Yes, in some models | Yes, in some models |
| Maintainability | Simple, few parts | Very good, world standard | Good, more manufacturer-dependent |
| Typical machines | Dedica, Bambino, many entry-level | ECM, Rocket, Lelit, Profitec | La Marzocca, Synesso, Faema E71 |
| Typical use | Entry-level, occasional use | Home and semi-professional | Semi-professional and professional |
All information is general guidelines; specific values vary depending on the model and configuration.
The unsaturated group is found in affordable entry-level portafilter machines. It is not actively kept warm in its resting state, which makes the machine affordable and quickly ready for use. The price for this is thermal instability: the first shot is often too cold because the cold group extracts heat from the water. Many users therefore pull a blank shot before inserting the portafilter.
The E61 solves exactly this problem via the thermosiphon. The group is permanently at temperature after heating up because hot water passes through it passively. No blank shot needed, no cold first shot. The disadvantage is the long heat-up time and high energy consumption.
The saturated group goes one step further: the group is directly connected to the boiler water and is permanently filled. This results in the highest thermal stability of all, but only becomes relevant at very high throughput, as found in professional environments. For ten espressos a day at home, the difference to the E61 is hardly noticeable.
The additional heating element in the group is not a separate type, but a feature that can be retrofitted to thermosiphon and saturated groups. It allows for faster temperature adjustments and compensates for heat losses at low throughput.
Maintenance and care: What you really need to do
The E61 is legendarily robust. But it does not tolerate maintenance laziness in the long run. The good news: if you follow a few simple routines, you will enjoy your machine for decades.
Backflushing, weekly: Insert a blind filter with cleaning powder, start the extraction, and build pressure 5 to 10 times for two to three seconds each. This removes coffee oils and residues from the group and the portafilter. Remove the shower screen regularly and brush it separately. Persistent residues collect underneath it.
Flushing before extraction: After longer breaks, flush for two to three seconds until the water no longer steams or sputters. The overheated water from the thermosiphon must be removed before you grind your coffee.
Group gasket, every 12 to 18 months: The rubber gasket in the brew head wears out over time and begins to leak. Replacement is simple and inexpensive. If you put this off for too long, you risk the gasket baking in place. Then it becomes more laborious.
Cam lubrication, annually: The camshaft, which controls the valves when the lever is moved, requires food-safe, high-temperature silicone grease. A common sign that lubrication is missing: the lever squeaks during operation. The cause is often intensive backflushing with detergent, which washes out the grease.
Descaling the gicleur, as needed: The small nozzle in the mushroom valve of the brew head is prone to limescale deposits. Anyone using hard water should check this component regularly. We have explained more about cleaning portafilter machines in detail here.
One of the most important side effects of E61 dominance: the 58mm portafilter diameter has become the world standard. Tampers, baskets, bottomless portafilters, distribution tools—everything in 58mm is available in mass quantities at affordable prices. Anyone who chooses an E61 machine benefits from a huge accessory ecosystem. For example, our bottomless portafilter for E61 groups.
Which espresso machines have an E61 brew group?
The list is long. Here is a selection of machines that we have tested ourselves and that are equipped with a genuine Faema E61 brew group:
- ECM Synchronika I and II, dual boiler, German build quality, with Flow Control in the Synchronika II
- Profitec Pro 600, dual boiler, very good build quality
- Lelit Bianca V3, dual boiler with Flow Control, outstanding price-performance ratio
- Lelit Mara X, heat exchanger with intelligent dual-use system
- Rocket Appartamento, heat exchanger, compact housing, classic design
- Bezzera BZ10, solid single boiler with good price-performance ratio
- Ascaso Steel Duo PID, heat exchanger with PID, good entry into the E61 segment
- Quick Mill Rubino, affordable entry into the E61 world
You can find a complete overview of all the espresso machines we have tested on our espresso machine test page. There, all machines are sorted by type: dual boiler, heat exchanger, and single boiler.
Conclusion
The E61 brew group is one of the few technical designs that, after over 60 years, can still be called state-of-the-art (at least for what it does). It is not perfect. The long heat-up times and high energy consumption are genuine weaknesses that modern thermoblock machines and rapid heating systems solve significantly better. If you want an espresso in three minutes in the morning, an E61 machine is not the right choice for you.
But for those looking for a machine that works stably, is forgiving, produces consistent results after being fully heated, and can be maintained and repaired for 20 years because spare parts are available worldwide, the E61 brew group is the right way to go. For people who take an active interest in espresso and see the warm-up time as part of the ritual, it is a natural choice.
Ernesto Valente's decision in 1961 to use heavy brass and a passive heat cycle still resonates today in every espresso bar where the characteristic click of the E61 lever announces the start of an extraction.
