It’s a design remnant, the brew water inlet holes were further up the cylinder LSM clone groups, so to avoid water washout of lubricant and longer seal life, they didn’t open the valve until the pressure seal had passed the port, so there was some upward travel before the valve opens.
However many manufactures found shorter seal life due to “nibbling” the seal edge as it passed the inlet ports, so many of them used an inner sleeve with the inlet ports at the bottom. A machine like the Londinium actually has 2 sets of seals pass the port and experience nibbling and water washout, which is why seals were being changed so often. Vesuvius group on the left.
Soy they changed the group sleeve, but left the rest of the group the same. Looking at the video, I can see a way to activate the inlet valve earlier in the piston stroke…have discussed with Paolo and he is going to look at designing something tomorrow.
As it is it works the same as all the other LSM clone groups, except you get a full counter current flow down the inner chamber (between the seal and group body for exceptional brew temp stability, compared to manufacturers who still have the inlet ports high up.
Hope it’s not all to technical….
