Introduction
There are a plethora of espresso options to serve diverse home espresso needs. To know more about different espresso (& near espresso) options for home use, refer to this post of ours - What features should I look for when buying my own espresso machine?
This post will focus exclusively on the most popular of the types amongst serious espresso aficionados - the semi-automatic espresso machine.
Here are four simple questions to ask yourself whilst shopping for a semi automatic espresso machine. These ideally should be asked by your hardware vendor, but in India they most likely won't, due to their own constraints & conflicts of interest in certain cases.
Q1 What are your current coffee consumption habits at home, what type of brew methods do you use? Or are you considering an upgrade of existing home espresso setup?
Q2 Do you prefer espresso based milky beverages or black beverages - espresso shots / americano etc?
Q3 Are you a daily or occasional espresso user - e.g., on holidays, weekends or while entertaining guests?
Q4 Do you have regular access to coffee beans from different regions/roasters of the world or mainly Indian coffee beans?
We hope that after reading this post, you will be able to to zero-in on a machine type, basis your habits & preferences.
Semi Automatic Machine Types
Semi-automatic machines typically feature a boiler, portafilter and a switch to activate/deactivate the pump to perform the espresso extraction. While several tasks are automated, machine users control when the extraction begins and ends with the help of a switch.
1. Thermoblock Espresso Machines
2. Single Boiler (SBDU) Espresso Machines
3. Heat Exchanger (HX) Espresso Machines
4. Dual Boiler Espresso Machines
Some Examples
Critical Additional Features
There are some important features commonly found in many premium espresso machine models which are noteworthy and enhance the espresso extraction experience.
E61 Group
This 4 Kg piece of thermosyphon semi-automatic system, although a nearly 60 year old design, is commonly found in premium espresso machines. Originally invented for the heat exchanger machine, it can also be found in dual boiler machines, in SBDU and sometimes, (although very rarely), in thermoblock espresso machines. Temperature stability is the biggest advantage of an E61 group head due to its thermal mass and the design also enables a form of passive pre-infusion.
PID temperature Control*
PID (Proportional-Integral-Derivative) controllers are used in a wide range of industrial applications for process control. In the case of an espresso machine, it controls the brew water temperature. The ability to precisely control brew water temperature, although it won't matter to most, is essential if you intend to experiment with different bean varieties, most specially delicate single origins from different regions of the world.
Pre-Infusion, Lever Mechanism & Pressure Profiling
Pre-Infusion is the process of wetting the coffee grounds puck at low pressure, before coffee extraction begins. Pre-infusion helps in levelling out inconsistencies in grind, dose or tamping and reduces instances of channeling in espresso extraction. By varying the applied water pressure and changing the duration of pre-infusion, one can impact the final extraction significantly.
This is where lever espresso machines come in, which provide a way of manually varying the applied brew water pressure throughout the extraction duration. Although there are many espresso machines which apply a pre-determined amount of pre-infusion which may or may not be user-adjustable.
At the extreme end, pressure (& temperature) profiling espresso machines, such as the Decent DE1, enable the user to define the pressure vs time curve for the entire duration of extraction. Using such a deep level of control, it is possible to brew a wide variety of coffee beverages from the espresso machine, such as a French press or a pour-over, not just plain espresso shots!
Pressure profiling, when combined with precise temperature control, also help to extract the maximum possible flavour and taste from delicately roasted single origin coffees which may otherwise not taste so nice on a conventional espresso machine.
Summary of machine types
A Thermoblock espresso machine is a great choice if you are just starting out on your espresso journey and may not necessarily have an espresso capable grinder or prefer buying pre-ground coffees. You will loose out a bit in terms of total beverage preparation time if you need to prepare a lot of drinks or if you would like to explore delicate single origin coffees from different parts of the world. The small form factor and low energy consumption are a bonus.
A Single Boiler (SBDU) espresso machine is recommended for those who like to drink their coffees black - espresso shots or americanos and only occasional milk based espresso beverages. Say an 80:20 ratio between the two. For those who like to experiment with different beans a PID temperature controller is important. SBDU machines are also great if you are the only espresso drinker in the house.
A Heat Exchanger (HX) espresso machine is ideal for those who drink primarily milk based espresso drinks although it is equally great for those who love their shots of espressos or americaxnos. A HX machine is great for those who are ‘creatures of habit’ and tend mostly to use similar type of beans over and over again, (thus reducing the need for frequent brew water temperature adjustments). For these reasons, HX machines are very popular in cafe environments.
A Dual Boiler espresso machine is a great match for those who drink a lot of milk based espresso beverages as well as a lot of espresso shots (and are not scared of heavy electricity bills). If you like to experiment with beans from different regions, especially delicately roasted single origins and have a very sensitive, Q-grader like palette, a double boiler is the best choice due to enhanced temperature stability of brew water temperature and the precise control you have over it.
Final Thoughts
Now, referring back to the four questions at beginning of this post, the choice of your next espresso machine can be summarised in the following table, with help of your newly acquired knowledge about semi automatic espresso machine types and their capabilities:
We hope you enjoyed reading this post as much as we enjoyed writing it. If you have any further questions, or if you feel we missed out on any aspect of semi automatic espresso machines, we will be happy to hear from you. Drop us a line here
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