TECH TALK
76 beanscenemag.com.auMaurizio Marcocci of Service Sphere discusses the role of the group
head, a common espresso machine part that serves a huge purpose.
T
o pull the best shots
possible, baristas need to
learn everything they can
about coffee extraction.
From grind adjustment
to water temperature, these factors can
all influence the flavour of coffee in the
cup. However, while trying to grasp
these complex concepts, many baristas
can skip over a key component of
espresso extraction.
Following our last Tech Talk where
we discussed the huge growth in
technological advancements within
modern coffee machines, this time we are
going back to the basics of an espresso
machine and exploring the humble
coffee group head.
Essentially, the group head is the part
of the espresso machine where water
from the boiler is dispensed into the
coffee filter basket. It acts as a meeting
point, connecting the machine to the
group handle and the water to coffee.
The E61, created by Faema, is the
most common type of group head
found in commercial coffee machines.HOW IT WORKS
E61 group heads use a thermosyphon
heating system, which sees the coffee
machine’s heat exchangers heat water in
the boiler. This hot water rises through
the group head causing it to heat up.
The water will continue to rotate from
the heat exchanger to the group head
and back to the boiler, causing thermal
stability throughout the day. This system
allows for natural pre-infusion of coffee,
where a small amount of hot water is
applied to the ground coffee at a lower
pressure than full extraction pressure.
This wets the coffee, allowing the barista
to gain full flavour from the blend.A TRIP DOWN
MEMORY LANE
The classic Faema E61 group head dates
back to the 1960s. Before this model,
manufacturers struggled to make coffee
consistent between machines, with
group heads of different shapes, designs,
and systems producing radically different
results.
The E61 became a group head
template for manufacturers, each
making slight variations on the design
to suit their own requirements leading
to the introduction of multiple boilers to
their machines.
The E61 design is a tried and tested
method – and half a century of research
and development later, many coffee
machine manufacturers still believe
it’s a better idea to build on its concept
than replace it with something new.COMMON
MISCONCEPTIONS
At Service Sphere, baristas frequently
tell us that the position of a group
handle must be at the 90-degree anglefor the machine to function correctly.
This is not the case. Instead, the further
across a handle sits when locked into a
group head alerts our technicians that
there is wear in a group seal, group
head, or handle.FREQUENT PROBLEMS
Most group head issues occur due to
a lack of proper maintenance. When
machine owners complain about the taste
of their coffee, we regularly find dirty
group heads and solenoids are the culprit.
Some group heads also use small
restriction points to maintain a particular
water pressure. If the machine has high
amounts of limescale, these points can
clog up and limit water flow. If this
occurs, we highly recommend you
contact your service technician as soon
as possible.
There are a few simple things baristas
can do day to day to minimise these
problems from occurring, saving time
and money in the long run. Baristas
should be backflushing their group
heads with a suitable cleaning productCoffee group heads
Maurizio Marcocci is the Director of Service Sphere.TECH TALK
76 beanscenemag.com.au
Maurizio Marcocci of Service Sphere discusses the role of the group
head, a common espresso machine part that serves a huge purpose.
T
o pull the best shots
possible, baristas need to
learn everything they can
about coffee extraction.
From grind adjustment
to water temperature, these factors can
all influence the flavour of coffee in the
cup. However, while trying to grasp
these complex concepts, many baristas
can skip over a key component of
espresso extraction.
Following our last Tech Talk where
we discussed the huge growth in
technological advancements within
modern coffee machines, this time we are
going back to the basics of an espresso
machine and exploring the humble
coffee group head.
Essentially, the group head is the part
of the espresso machine where water
from the boiler is dispensed into the
coffee filter basket. It acts as a meeting
point, connecting the machine to the
group handle and the water to coffee.
The E61, created by Faema, is the
most common type of group head
found in commercial coffee machines.
HOW IT WORKS
E61 group heads use a thermosyphon
heating system, which sees the coffee
machine’s heat exchangers heat water in
the boiler. This hot water rises through
the group head causing it to heat up.
The water will continue to rotate from
the heat exchanger to the group head
and back to the boiler, causing thermal
stability throughout the day. This system
allows for natural pre-infusion of coffee,
where a small amount of hot water is
applied to the ground coffee at a lower
pressure than full extraction pressure.
This wets the coffee, allowing the barista
to gain full flavour from the blend.
A TRIP DOWN
MEMORY LANE
The classic Faema E61 group head dates
back to the 1960s. Before this model,
manufacturers struggled to make coffee
consistent between machines, with
group heads of different shapes, designs,
and systems producing radically different
results.
The E61 became a group head
template for manufacturers, each
making slight variations on the design
to suit their own requirements leading
to the introduction of multiple boilers to
their machines.
The E61 design is a tried and tested
method – and half a century of research
and development later, many coffee
machine manufacturers still believe
it’s a better idea to build on its concept
than replace it with something new.COMMON
MISCONCEPTIONS
At Service Sphere, baristas frequently
tell us that the position of a group
handle must be at the 90-degree anglefor the machine to function correctly.
This is not the case. Instead, the further
across a handle sits when locked into a
group head alerts our technicians that
there is wear in a group seal, group
head, or handle.FREQUENT PROBLEMS
Most group head issues occur due to
a lack of proper maintenance. When
machine owners complain about the taste
of their coffee, we regularly find dirty
group heads and solenoids are the culprit.
Some group heads also use small
restriction points to maintain a particular
water pressure. If the machine has high
amounts of limescale, these points can
clog up and limit water flow. If this
occurs, we highly recommend you
contact your service technician as soon
as possible.
There are a few simple things baristas
can do day to day to minimise these
problems from occurring, saving time
and money in the long run. Baristas
should be backflushing their group
heads with a suitable cleaning productCoffee group heads
Maurizio Marcocci is the Director of Service Sphere.