TECHNICIANS' manual
- English -
15 di 52
2.8.1 Heating unit
The heating unit is made of copper sheet metal (22). The
heat exchangers (B) are assembled onto this unit and are in
turn connected to the dispensing group. The water used for
dispensing coee is taken directly from the heat exchanger.
During the dispensing process, cold water is sent inside the
exchanger by means of the motor pump. Cold water and the
pre-existing hot water are mixed together inside the heat ex-
changer, in order to obtain the optimal water temperature for
coee infusion.
The heating unit is electrically heated by an electric heating
element immersed in the water (A).
B
A
22
2.8.2 Overflow device
The cover installed on the pressure relief valve makes it pos-
sible to collect any water and steam which may leak from the
heating unit due to a malfunction and channel it to the drain
tray, via a special hose.
2.8.3 Pressure relief safety valve
The pressure relief safety valve has a calibration of
0.19 MPa (1.9 bar) in order to ensure that the pres-
sure in the steam heating unit does not exceed 0.21
MPa (2.1 bar). Should a fault occur, the capacity of
the valve is such as to be able to eliminate all the
excess pressure in the heating unit.
The safety valve should be checked regularly as indi-
cated in Chap. "7. MAINTENANCE AND CLEANING" on
page 31.
2.8.4 Multifunctional dispenser
It consists of an expansion valve and an internal check valve.
• Expansion valve (A): The cold water sent from the pump to
the heat exchangers is heated. This heating causes an in-
crease in the volume of water. To
limit pressure increases in the
hydraulic circuit, the valve limits
the maximum internal pressure
of the circuit to 1.2 MPa (12 bar).
• Internal check valve (B): Its
function is to prevent water
from backflowing into the ma-
chine’s internal hydraulic circuit
from the heat exchangers.
2.8.5 Negative pressure valve
The purpose of the negative pressure valve is to pre-
vent liquids from back-flowing through the steam
nozzle when they are being heated. Furthermore, the
excess air inside the heating unit is removed during
the machine's heating phase.
2.8.6 Pressure switch
The pressure switch makes it possible
to control the heating unit pressure by
activating or bypassing the heating ele-
ment in the heating unit. Any pressure
switch calibration can be carried out
with the machine in operation by turn-
ing the screw (A) located on the body of
the component.
B
A
A
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