La Marzocco kb90 Series, Manual

Page: 17 / 144

EN
17
boiler to a predetermined level and will
shut off when full.
Note: It may happen that the air inside the
steam boiler builds up pressure (which
may be detected through the pressure
gauge - item 2, fig. 1) when the water is
allowed to flow in; this “false” pressure
must be eliminated by opening the steam
valves (item 8, Fig. 1).
b) Turning the espresso machine on
Once you have completed these
procedures, check the display. Press enter
to confirm that the preceding procedures
are complete.
The installation is now complete and the
espresso machine should be heating to the
operating temperatures.
2) Waiting for the espresso machine to heat to
operating temperature
During this time, it may happen that the
pointer of the coffee boiler pressure gauge
reaches as high as 14-15 bar. This may
happen anytime that the heating element
is in the on condition. In this case it is
necessary to adjust the expansion valve
(Fig. 3) in such a way that the pressure
may never exceed 11-12 bar. In normal
operating conditions, the coffee boiler
pressure gauge can read anywhere from
0-12 bar.
When brewing, the pressure should be set
to 9 bar.
When the steam boiler reaches operating
temperature, the light on the Hot water
dispense button will light.
When the espresso machine is ready to
operate all lights on the keypads will light.
3) Brewing after first installation
Once the first installation procedures are
finished, before proceeding with brewing
coffee, hot water and steam, please follow
these steps:
- Engage the portafilters by inserting
them into each group, brew water through
each group for at least two minutes.
- Being careful to avoid burns, turn on
each steam wand for at least one minute.
- Turn on the hot water valve for the time
necessary to allow the following quantities
of water to be brewed:
At least 1 liter for a 1/2 group machine
At least 2 liters for a 3 group machine
4) Installing the portafilters
Install the portafilter(s) by inserting them
into the group and lift the portafilter knob
rotating it from top to bottom until the stop
position is reached. When the portafilters
are inserted properly, you can press any
of brew buttons to start the flow of water
through the portafilter. You should allow
hot water to pass through the empty
portafilter(s) for a few seconds each time,
in order to pre-heat the portafilter.
Note: It is important to leave the portafilters
installed in the espresso machine when
not in use. The portafilter must remain
heated for the brew process to function
correctly.
5) Water pump
Whenever you are brewing coffee, and you
can adjust the pump pressure by turning
the by-pass screw (below the plug located
on the side to which the pump power
supply is connected) clockwise to increase
and counter-clockwise to reduce pressure.
Adjust pressure only when at least one
group is brewing coffee.
Note: When the heating element in the
coffee boiler is energized, the water will
expand increasing the start-up pressure.
Once the maximum pressure is reached,
the expansion (safety) valve should start
working by discharging a few drops of
water, in order to prevent such pressure
from exceeding 11-12 bar.
In case the pressure exceeds 12 bar,
you must adjust the expansion valve by
unscrewing the cap slightly. If this is not
sufficient, remove the valve and clear away
any calcium deposits. This remedy is valid
also in case the valve remains open in the
drain position (i.e. the pressure cannot
increase to 8 bar approx.).