How does it turn 9 bar pressure on E61

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#1: Post by smartalek »

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

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Team HB

#2: Post by another_jim »

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.
Jim Schulman

smartalek (original poster)

#3: Post by smartalek (original poster) »

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 .

smartalek (original poster)

#4: Post by smartalek (original poster) »

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