OldGregg Question - are these machines supposed to drip/leak when the group is warming up? The pressure reading on the touch screen reads about 9-10 bar when coming up to temp, and there is a pretty constant drip of water.
Absolutely yes, the group itself has an open chamber (double skin). This is quite normal and only a little will come out of the water inlet holes below the piston.
The actual water flow in the group is what would be termed a counter current flow. It comes from the boiler from the inlet valve near the top of the group chamber, slows down an inner chamber (in the double skin), then back up following the piston as it rises. It’s one of the reasons it’s such a stable group as the temperature is equalised along the height of the group during this process.