I have owned a Rocket Giotto Evoluzione v2 for about 1,5 year now and therefore have brewed a lot of espressos in that period. During that time I had tuned the extraction process and thought that things couldn't be better. Nonetheless I found that the second manometer only showed the pump pressure and therefore not the pressure at the brew head.
During the extraction process, the arrow of the pump pressure manometer would show a satisfying 9 bar and I assumed that the brew pressure at the brew head would be similar to the pump pressure. I was in for a chock when I discovered that this wasn't the case.
I have thereby created a short and simple how-to guide, that will show you how to adjust the pump pressure on the Evoluzione v2, so you will achieve the correct 9 bars of pressure at the brew head. To perform this guide you will need a portafilter with a manometer/pressure gauge (above picture).
The Rocket Evoluzione v2 comes with a rotary pump and therefore has the ability of connecting the machine directly to a water source, instead of using the water tank. Rocket have designed the machine so you easily will be able to adjust the pump pressure from the outside of the machine.
1. Turn on the machine.
2. Locate the adjustment screw (above picture).
3. If you want to increase the pump pressure, turn the adjustment screw clockwise and anti clockwise to decrease the pump pressure.
4. Mount the portafilter and start the brewing (Remember to tighten the portafilter firmly, because it will unmount when the pressure is building up).The pressure gauge will now show you the actual pressure at the brew head, and if your machine delivers 9 bar at the brew head, then all is perfect. If your machine - like mine - was providing a pressure of 8,0 - 8,5 bar at the brew head, then you should adjust the adjustment screw like described at step 3.
When I was done adjusting the pump pressure, the pump pressure showed about 10 bars of pressure, to perform the optimal 9 bars of pressure at the brew head.
Did the adjustment have any affects on the espresso?
YES - the main change was the extraction flow! Before, the espresso could run perfect in the start off the brewing process and afterwards the water could soak though the puck, causing a very thin and bitter extraction. The pressure is now creating a firm puck and therefore preventing channeling, which leads to a way better extraction.