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. My Espresso! E-mail me at frcn digitalpath. Heat Exchangers have been around for a long time. A basic one resides in your kitchen in the form of a double boiler.
In an espresso machine the heat exchanger works on the same principle of taking a heat source and transferring the heat energy to another object. The boiler itself supplies the user with steam for stretching milk as well as hot water, but the heat exchanger helps create temperature-regulated water for brewing espresso.
HX machines have larger boilers than single boiler machines. In most all cases, much larger. A larger mass of water means greater temperature stability. It also gives more room and stored heat energy for steam. The E design is found on a lot of machines because it works. How well? It depends on a lot of other factors. If you look HERE at the review of the Vibiemme Domobar Super you will see Dave Stephens's graph of consecutive shots which is a most impressive demonstration of what a quality machine can do: Read the article, not so much to sell you on that machine but to demonstrate the stability and shot-to-shot performance of a well-designed machine.
The espresso? It was superior right away and as I become more accustomed to the machine it gets better. Be sure to budget for a high-quality grinder as well.
Something with infinite stepless adjustment will help get the best out of any machine. That should be the initial investment. And of course, a source of fresh coffee- silk purses and sow's ears and such Sponsored by Weber Workshops. The next step up from a single boiler thermostat control price wise and quality wise is either an HX or double boiler. Tamping Mats. Steaming Pitchers.
Group Gaskets Shower Screens E Pressure Relief Valves Vacuum Breakers. John Guest. Burrs Hoppers. Pressure Stats Fuses Relays Solenoids. Espresso Coffees. Espresso Espresso Pods. Chris' Coffees. Regular Decaf Flavored Organic. Fractional Packs. Coffee Grinders.
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