La Marzocco mini Serie Manuel page 11

7) Adjusting the expansion valve.
The expansion valve is a component
that limits the maximum pressure in
the Integrated brew group. Heating the
integrated brew group causes the water
within to expand. Since the integrated
brew group is completely saturated, the
expanding water causes an increase in
pressure within the boiler. Without a
safety device the increase in pressure
could cause a rupture in the boiler.
The pressure in the integrated brew group
should never exceed 12 bar. The valve is
hot, so, using adequate protection, rotate
the expansion valve clockwise to increase
pressure. To decrease pressure, rotate the
expansion valve counter clockwise (see the
following diagram).
Increase
pressure
Figure 2 - Expansion Valve Adjustment
Decrease
pressure
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