Operation Manual

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1 - To sense the temperature of the water in the brew boiler there is a metal probe that penetrates into the
brew boiler and is immersed in the water inside the boiler. The hollow probe contains a thermal sensor that
is connected to the electronics in the machine. Think of it as an electronic thermometer.
2 - The electronics that control this system is called a PID which stands for “Proportional, Integral, Deriva-
tive.” These three things constitute a mathematical process that figures all this out. To put it simply, the PID
is a digital thermostat that is programmed to know how the device to which it is connected behaves, and how
it can best control it in a precise way. Vibiemme has pre-programmed the PID with the information it needs
to best control this specific system.
3 - The PID’s electronics can’t directly handle the wattage that the heating element draws, so a solid state
relay (SSR) is used. This device isolates the high current that the heating element draws from the sensitive
electronics of the PID. Think of it as the heating element’s switch that the PID can turn on or off.
4 - The heating element is immersed in the brew boiler’s water, and as it heats the water the PID’s probe senses
the water’s temperature and that information is always being processed in the PID to give you precise brew-
temperature control.
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Brew
Boiler
E-61
Group
PID
Control
Box
SSR
The numbers in the illustration refer to the numbers in the text below to make it easier to follow along:
Brew Boiler, PID Control, and the E-61 Group
NOTE: The diagrams on these pages are not to scale and are designed for general educational pur-
poses only to illustrate the function of the machine in a simple-to-understand manner. These do not
depict the exact design features of the espresso machine. They are not be used for technical support
nor repair purposes. They are diagrammatic illustrations to help you gain a better understanding of
the basic operation of the major internal components of this system.
There is a lot of technology and precision design in the working of the Double Domobar which help bring
you such great espresso. Much of that technology is hidden inside the case and deep in the boilers. A visible
portion of that technology is the digital display on the face of the DD. In the center of the front panel, between
the gauges, the blue LED displays the brewing temperature setpoint. The following explains how the DD uses
electronic technology to control the temperature of the brew boiler.