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1.3.3
Filling the machine
The float tank and the boiler are connected by a siphon hose. Together they create a communication entity.
When the machine is switched on for the first time the float tank (Fig.2) is empty and the float (Fig.2,A) in a
lowered position.
D The magnetic valve (Fig.1) opens and fills the float tank with water at a pressure−independent speed of 2
litres/minute.
D The water in the float tank runs through the hose under the float tank to the boiler.
D When the water has reached a level that pushes the float upward, the water level in the float tank is equal
to that in the boiler.
The magnetic valve is switched off.
Please note:
− Because the float tank fills faster than the water 'drops' into the boiler, the filling process will take place
with short intervals.
1.3.4
Heating
Now that the system has been filled with water (Fig.1,3A), the heating element is switched on by a separate
mechanical relay. The temperature sensor (Fig.1,3C), which is on the outside of the boiler, measures the
actual temperature of the water. The temperature sensor ensures that the water in the boiler is heated to the
desired temperature. A thermometer flashes on the LCD display during the heating phase. This indicates
that the machine is not yet ready for use.
The temperature sensor is an NTC (Negative Temperature Coefficient) thermistor. The higher the measured
temperature, the lower the sensor's resistance. Hot water has a lower specific weight than cold water. As a
result, the hot water in the boiler will not flow back to the float tank through the siphon hose at the bottom.
That part of the system will therefore remain cold. This is very important because the parts in the float tank
are sensitive to limescale. The temperature sensor is on the outside of the boiler. As a result, there is no
feed−through in the wall meaning that the system will not leak over time. This measurement is less direct.
That is why the temperature is regulated proportionally.
The heating switches on for a specific amount of time and then off for a specific amount of time. A
measurement is made after the period that the heating has been off. The value measured determines the
length of the next heating period. The higher the temperature in the boiler, the shorter the moments that the
element is on, and the longer the intermediate time becomes. This enables an accurate temperature to be
obtained in the boiler.
There is a second temperature sensor on the boiler (Fig.1,3B). This sensor monitors the dispensing
temperature of the dosed water. If this sensor measures a too low temperature, the machine is blocked.
No more water is dosed.
3
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