La Marzocco Espresso Machines Guideline
The La Marzocco espresso coffee machines work by forcing hot water under high pressure
through finely ground coffee held in a portafilter. The brewing process uses several key
components to accomplish this process.
Nearly every other espresso machine manufacturer uses a single boiler and heat exchanger
located inside the steam boiler. Water for brewing espresso is solely dependent on the
temperature of the single steam boiler and this creates inconsistent brewing and steaming
conditions, thus producing inconsistent drinks.
The La Marzocco espresso machine uses a unique two-boiler systems to isolate and perform
operations in the best possible conditions.
The rear boiler is dedicated to the steam and hot or tea water functions.
The front boiler has the sole purpose of providing brewing water at the correct temperature
and pressure for the coffee the
barista
is going to brew.
These temperature and pressure parameters are adjustable independently of any other
function of the espresso machine. They are also consistent though most any level of operation.
HOW DOES IT WORK?
Cold, filtered water enters the brewing boiler through a pump which raises the water pressure
to 9 bars to allow the water to flow through the finely ground coffee.
Then the water in the boiler is heated by a heating element, which is controlled by a
Temperature probe connected to a CPU which control and sends power to the element when
the water temperature is low and shuts off power to the element when the water is at
operating temperature.
This means the temperature of the coffee brewing water can be set precisely depending on the
operator's taste, the roast or blend of the coffee used.
When the barista puts the portafilter into the brewing group, it forms a watertight seal
between the portafilter and the group gasket.
When the user presses the brew switch, a solenoid valve opens and the pump generates
pressure to force the hot water from the boiler through the group and the diffusion screen and
screw, then into and through the ground coffee, producing the desired volume of espresso,
which is brewed into heated cups or shot glasses.
On automatic (AV) models, the water is measured by a flowmeter.
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