When the boiler is first filled (when the machine is new), and from that time onward, the 3-Way valve now has something to do. It's job is to close off the exit of the boiler so that the water being heated cannot escape. This is the "at rest" state in that the machine looks like this whether it is off or if the power switch (only the power switch) is in the on position. Note that the brewhead is open to the atmosphere through the 3-way and into the drip tray area at this time.