When the machine is turned on, the controller will display the boiler temperature
in the machine. The temperature reading will start to increase after 30-60
seconds. As the temperature approaches the set value, you will notice that the
panel light next to the power switch will start to flash. This flashing indicates that
the controller is cutting the power to the heater such that the temperature will not
overshoot as it approaches SV. After the temperature has stabilized within ±1
degree of SV AND the machine has been NonO for 45 minutes, it is ready to
produce espresso.
Figure 1 shown the brew water temperature changes with time. The reason for
such delay is due to the structure of the Silvia machine. The boiler of the
machine has only a thin section connected to the grouphead. It will take a while
for the heat in the boiler to transfer to the grouphead. In general, it takes 25 to 45
minutes to get the brew water temperature stabilized. During the warming up
period, we suggest user to install the empty portafilter on the machine. After the
controller stabilized at SV, run the pump for 4 to 6 fluid oz of water (120-180 ml)
to flush the grouphead and portafilter. That will speed up the warming up process.
Figure 2 Correlation between PID controller set temperature and brew water
temperature detected at grouphead measured by Scace Thermofilter. Top,
display in degrees Celsius. Bottom, Display in degrees Fahrenheit.
Figure 2 shows the correlation between the PID controller set temperature and
brew water temperature. The controller in the Auber instruments[ PID kits has
been calibrated with its sensor to the accuracy of 1 degree C before shipping.
However, due to the machine structure variations, the brew water temperature of
different machine can have 1-2 C difference when controlled by the same PID
controller kit. For detailed relationship between the PID setting temperature and
brew water temperature, please read the file named "Temperature Performance
Study" in the CD that came with the kit.
It should be noted that the setting temperature we recommended is lower than
some people suggested on the internet forums. As SV can be easily changed, it
will up to the user to decide what the best temperature is for their espresso.
