Coffee Data Science
Cheaper Espresso Machines == Bad Water Input
This includes your favorites for sure
I have previously tested the Gaggia Classic and Decent groupheads, and the problem with these machines is that for water input, the water comes into the water diffuser from the side. There is a ring for the water to fill up, and in theory, at steady state when the system is pressurized, this shouldn’t matter. The trouble is getting the system pressurized.
This is how water enters for the Breville espresso machines:
The transient state from unpressurized to pressurized will be uneven as a result, and this matters because the water flow through the puck will be initially uneven.
This design has been used throughout the industry. However, people don’t look at this part of a machine when buying a machine.
Lelit:
I suspect this defect in design is why people with <$1,000 machines are still interested in upgrading to something better. It is hard for the user to debug problems resulting from this design.
Rancilio:
I found this design after a series of experiments to optimize on the Decent Espresso machine. In the shot, it isn’t always clear, but usually you can see the stream of coffee is eccentric.
There is a dependency on flow rate to say if the stream tends to the right or the left, which is always why this problem is challenging for people to see. Usually, the flow rate also depends on the temperature of the water so the requirement for temperature surfing some machines is also a function of flow surfing.
I used to recommend the Gaggia classic or Silva or even the Breville as entry level machines, but now, there is a big asterisk. For entry level, the Flair or Rok stand as the two machines with even water input even though they aren’t as convenient as a semi-automatic machine.
Please don’t take a technical criticism personal; I want the best for these machines.
Just fix the water distribution.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
