Cuprajake I see no brown/dirty water coming out the drain valve. The water comes clean with no residues.
So if the question is, are you forced to make backflushes because it dirties the group due to the vent pressure feature?
IMO, the answer is no. I see clear water as I said. And I know Nurri did some testing about this.
I think this is because when you open the vent valve, there’s no negative pressure at the shower screen that may suck up the coffee. In fact, I would say there’s positive pressure in the shower and positive pressure at the drain circuit, thus it drains the water.
