Hi everyone,
I was looking at E61 group head and I have a question. How machines that use E61 group head know when to turn the pressure from static(off) to 1bar then to 9bar?
From what I see there is no position sensor on the manual lever so I does the controller know when to change from 1bar for preinfusion to 9bar for brewing?



Thank you

The lever, as shown on the diagram you included, is attached to a valve inside the group that opens the water path when it is up halfway. It also has a cam that pushes a button behind the group that turns the pump on. This when it is all the way up. If the group is plumbed in with a rotary pump, opening the water path without activating the pump will allow water to flow to the group at line pressure. If you are not plumbed in or have a vibe pump, the middle position does nothing at all, since there is no water pressure to create flow.

Hi Jim thank you for the explanation, it makes sense but in all the E61 diagram I saw, I see the cam but I don't see the button/switch you mentioned .

Ohhh I get it now, the switch is separated from the GH Thank you very much!