Espresso machine how does it work

Vibration pumps are more likely to be found in your espresso machine at home and only create pressure when pulling an espresso shot. The boilers are some of the most important espresso machine features to look at. For espresso, just like any other coffee, your water needs to be at the optimal temperature to allow for proper extraction.

Water is fed into the boiler through a one-way valve where it is collected and heated. There are 3 main types of boilers in a semi-automatic espresso machine: single boiler, double boiler, and heat exchange. A single boiler is exactly what it sounds like. Water for both brewing espresso and steaming milk is collected and heated in one single tank. The problem with a single boiler is that you cannot brew espresso and use the steam wand at the same time. The ideal temperature for steaming milk and the ideal temperature for brewing espresso are drastically different.

Using the same boiler for both means having to wait for the water to heat up or cool down after using each function before you can move on to the next one.

The isolated section in a heat exchanger provides water that is cooler and suitable for brewing. This is achieved by continuously supplying water through the isolated element, into the group head, and back down into the machine. Similar to the single boiler, a dual boiler is very appropriately named.

Espresso machines with a dual boiler have 2 separate tanks instead of one that does all the work. One tank heats water for brewing while the other heats water for steaming. Related: Dual Boiler vs Heat-Exchanger. This is pretty much where the magic finally happens.

The group head is the part on the front of your espresso machine where the portafilter locks into place. These nifty devices connect to the heating element and manage on-off cycles to maintain optimal boiler temperatures. Without this technology, heat levels can fluctuate and cause inconsistency in your final espressos.

Most espresso machines also have a steam wand. This is the thin metal nozzle attached to the side of the espresso machine. Steam wands work by releasing steam from the hotter of the two boilers through this thin pipe directly into the milk.

The pressurized steam warms and adds texture to the milk, allowing the creation of cappuccinos and lattes. Credit: Christy Duggan. The group head is the final stop before the coffee reaches your cup. This is the part that brings the hot, pressurised water into contact with the compacted puck of coffee. This is where you will find the portafilter — the metal filter basket that holds the ground coffee.

Group heads also include a portafilter lock, a pressure switch to regulate boiler pressure , and a channel to allow water to move from the boiler to the portafilter. Some people prefer to use a bottomless, or naked, portafilter. This means that the basket of the portafilter is exposed.

It helps a barista to dial in their grinder accurately and quickly. A shot of espresso pouring into cup. There are two major types of group head: saturated and semi-saturated. At this stage, the water inlet cam will complete raising the brew valve while simultaneously sealing the pre-infusion valve. With the pre-infusion valve sealed, the intensely pressurized, hot water is only allowed to travel out through the dispersion block and onto the ground coffee.

At the end of the brewing cycle, the lever is returned to the down position and the pump is deactivated. At this point, the water inlet cam seals the brewer valve, ending the flow of water to the rest of the group. At the same time, the water inlet cam reopens the pre-infusion valve and the drain valve; this releases any back pressure in the portafilter basket and dries the spent puck.

As such, the group head acts as an extension of the boiler and is saturated with hot water hence saturated group head. Instead of waiting for large chunks of brass to come to temperature, a saturated group head will quickly come to correct temperature with the water in the boiler. When the machine is activated, the three-way valve opens the lines running to the boiler and the dispersion block while closing the waste line.

If the machine is designed for preinfusion, it will wait to activate the pump; instead, it allows the ambient pressure of the hot water to push through the dispersion block to slowly soak the bed coffee. Once the pump is activated, the full nine bars of pressure are applied to the water and it is pushed through the open lines and out of the dispersion block.

When the shot is done, the pump deactivates. At the same time, the three-way valve closes the line running to the boiler while opening the waste line; this relieves back pressure and removes moisture from the spent puck. Over the last decade, this has become the most common group head design for high-end commercial machines.

Generally, this kind of group head is more costly to produce, due to the precision welding and thick metal builds. Because of the exposed design, it requires careful maintenance and repair; generally, we recommend most repairs be performed by trained technicians. For most home users making smaller quantities of drinks, we tend to recommend Semi-saturated Group Heads. The biggest difference is that instead of having the whole group head exposed to the boiler, the area directly above the dispersion block is separated from the boiler.

The gicleur line runs from the extended boiler into the dry area above the dispersion block. Semi-saturated Group Heads are less expensive to produce and tend to be easier to repair than a fully saturated group head.

Unlike the mostly manual E61, both saturated and semi-saturated group heads depend on an internal computer to function. Different machines will offer more robust programming and control, depending on the kind of computer used. A portafilter, shortened from portable filter, is a metal filter basket set inside a handle. Finely ground coffee is put into the filter basket, then is compressed by tamp, before the portafilter is inserted and locked into the machine.

There are many different sizes of a portafilter. However, the two most widely used are the 53mm and 58mm. While the 58mm is the most common size for commercial machines, both sizes will produce excellent espresso.

Both can use the same amount of ground coffee when fitted with correct baskets. The most important thing to know when purchasing either a 53mm or 58mm portafilter is to make sure to buy the corresponding size tamper. So now that you know a little bit more about how espresso machines work, let us help you understand how to choose the best espresso machine for your needs. Contact Help Center Tech Support.

How Do Espresso Machines Work? The Water Source Every espresso machine needs water to function. The Pump — The Heart of Your Espresso Machine To give water the strength to push through a tightly packed bed of finely ground coffee, machines need pressure: 9 bars of pressure to be exact, which roughly translates to psi.

The Boiler — Bringing the Heat Water needs to be both pressurized and heated to turn coffee into a brilliant espresso. The Boiler — Taking Control of Your Temperature For all the intensity of pressure and heat, making espresso is a delicate art; even small changes in water temperature can drastically affect the quality of your shot. The Steam Wand Espresso is only one part of the overall machine - especially machines designed for the American market. The following are the four ways different machines solve the problem of keeping some water boiling and other water at a lower temperature: In Single Boiler machines, the boiler has one heating element with two thermostats.

The steam wand is used to heat and froth milk for use in various espresso drinks. This wand is connected to the heating vessel. When the user puts the valve in the steam position, steam from the heating vessel is released out of the wand and into the milk. One of the lights indicates that the machine is on, and the other indicates if the heating chamber is up to the proper temperature.

The valve is used to start the flow of water through the coffee in the porta-filter or to start the flow of steam from the steam wand. It also engages one of two micro-switches that control the pump and heating element. Assuming that the machine already has water in it, you start by turning the machine on and waiting for the heater light to indicate that the heating vessel has heated the water to the ideal temperature just below boiling.

Next, you put the ground espresso coffee into the basket and tamp it down. You install the porta-filter by twisting it into the machine, and you place one small cup beneath each spout.

You then turn the valve to the espresso position. This engages the micro-switch that starts the pump, which pressurizes the heating chamber and hot water to about 15 atmospheres psi of pressure. This forces the hot water through the ground coffee and out of the spouts.

Ideally, it should take about 25 seconds for about 1. When the espresso has filled the cups, you put the switch back into the middle position. Most likely, you'll want to steam and froth some milk next. To steam some milk for, say, a cafe latte, you place a container with some cold milk under the steam wand so that the wand is submerged. Then, you turn the valve to the steam position.

This energizes the resistive heater, which quickly boils the water in the heating vessel and opens the valve, starting the flow of steam out of the nozzle. The pump runs intermittently to keep the heating vessel supplied with water.