How a Silvia Works
All wiring
Off
On, heating up
On, at temp
Brewing espresso
Steam, heating up
Steam, at temp
Pumping hot water
Overheated
Modification for PID
Dual Setpoint PID
Advanced Dual Setpoint PID

Coffee Cup
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Hot Water Switch is On

With the hot water switch turned to the on position, the pump is activated but the 3-way valve is still at rest. The pump pressurizes the boiler, and when the steam knob is opened, hot water will be pumped through the steam wand as this is the only vent from the boiler that would "normally" be opened at this time. The exception is when the hot water knob is left closed and pressure builds up too high in the boiler. The bypass valve will open and water will be pumped back to the boiler. Note that the heating circuit is independent of the pump circuit and the heating element is free to turn on and off during this process.