You’ve probably heard people say that they like their coffee done a particular way. Some individuals prefer a blend of coffee beans that bring into being a unique taste or aroma using espresso machines. A good number of people prefer a shot of espresso that has been brewed using a particular type of coffee bean. Nevertheless, the amount of thought put in preparing the coffee is what really matters: whether espresso or regular coffee.
In essence, the style of making coffee is what brings out the “espressos” in coffee. No particular plant or roasting technique produces espresso beans. However, forcing regular coffee through pressurized water, which then passes through a filter and a “puck” of coffee.
So, how do Espresso Machines Work?
There are many types of espresso machines. The workings of these machines may differ slightly, on some occasions, but the basics are usually similar. For instance, commercial machine and top-class home espresso machines have boilers. The difference may arise when it comes to figuring out where the water comes from and why.
The Boiler
Most espresso machines have a cylindrical copper boiler (the Boiler). with tubes spread over it and a compressor connecting to some of those tubes. The compressor functions as an electric motor that pressures the water running through the tubes. Additionally, a good number of valves and wires plus a few circuit boards also help control how the machine works.
The cylindrical boiler acts as a reservoir for water. The water in the cylinder usually kept a little more than half full. and then subjected to heat from a coil that installed in the boiler. A water heat controller used to measure the temperature in the boiler and, as a result. The water temperature within the machine kept at a fixed temperature measure: the heater turns on off as required.
The Control Circuitry
Electrode use to ensure that the depth of the water in the boiler maintained. To pass current through the electrode, a control circuitry installed in the coffee machine regulates the flow of electricity to the boiler. The electric current disconnected if the water in the coffee brewer falls below the tip of the electrode. This prompts the controller to open a valve that allows the flow of water from an external source.
It’s prudent to note that the external water source pressurized since the water in the cylinder is pressurized. This means that it should have the force required to push water into the boiler once the valve opens: typically 20 to 30 psi. Once the water touches the tip of the electrode, the control circuitry turns the water intake valve off. The water level in the boiler should keep constant at all times.
The Pressure Gauge
The pressure gauge used to register the pressure that is inside the boiler and the extraction pressure. The pressure should maintain at 1.5 bars (indicated on the upper side of the pressure gauge) producing good steam. If the pressure is lower than 1.5, the espresso machine will not produce good steam. Moreover, if the pressure is higher, it poses a hazard: if the pressure goes beyond 1.8 bars, a safety valve blows.
On the lower side of the pressure gauge, you will see a reading that indicates the extraction pressure of the espresso. The pressure should keep between 9 and 11 bars: when pulling a shot. Also, when not pulling shots, the gauge reflects water line pressure from the water source.
The Portafilter
The removable portafilter part of the machine meant to hold the ground coffee. A basket, a handle, and a two-pronged spout used to assemble this part of the coffee machine. The coffee tamped and packed in this section. Thus, the portafilter fastened to the group head to form a seal. Below the basket, you can find two spouts where the espresso emerges and flows into an espresso cup.
It is prudent to note that the water used to brew the coffee does not come from the boiler, it comes from your building’s water supply: the plumbing system.
Steam Wand
This used in frothing milk which used in various espresso drinks. It simply forces steam into your milk, gently warming it with pressure. At the same time, it adds air to the milk, which causes it to froth. It also connected to the heating vessel in which when you put the valve in the steam position, steam from the heating vessel released out of the wand and into the milk.
How is Espresso Extracted?
The water for brewing the espresso channeled through a loop that exits the group head, passes via the solenoid valve, through the boiler, and then finds its way back into the group head. This process intended to adjust the flow rate ideally, in a bid to control the temperature of the water in the group head. When not pulling a shot, the water pump turns off, and the solenoid valve prevents it from working. However, water flow maintained.
Why should water fow maintain?
The reason the water keeps flowing is to ensure the group had remained at a constant brewing temperature. This achieved through Thermo siphoning, a passive physical mechanism. If you chose to record the temperature of the water through the various points, you would discover some insightful revelations. Water is hottest as it leaves the boiler and then cools down slightly as it approaches the group head. As the water exits the group head, it loses more heat and is much cooler as it reaches the boiler again. The various changes in temperature allow the automatic flow of water around the circuit, keeping the group head hot.
How is Water for Coffee Preheated?
The heat exchanger is quite efficient when it comes to heating limited amounts of water, such as water for a cup of coffee. However, it cannot sustain the flow of heated water indefinitely. As a consequence, the hot water spigot, installed in the coffee machine, utilizes water from the cylinder. Home coffee brewing espresso machines do not have boilers. Instead, they have heat exchangers: for steam and espresso. This is why commercial coffee machines have a distinct, rich taste that is not comparable to that produced by the economical home espresso machines.
The Takeaway
The workings of coffee brewing machines complicated. However, knowledge of how they work is essential if you are considering purchasing one. The information on how they work helps you find what you are looking for much more effortlessly.