Has any of you needed to adjust the expansion valve? I received my Mini yesterday afternoon. The initial set up and everything was all fine. Pressure gauge showed 10 bar when machine was ar rest. Today, I came home from work, the gauge sat at over 14 bar. I flushed the mini. While flushing with no PF in group it showed 9 bar then jumped back to almost 15 bar when I turn the switch off. With the blank filter, it ramped up to 10 bar. This is my first rotary pump machine. When I adjust the expansion valve, what is the blind pressure I should aim for? Can I ask what blind pressure your machines are set at? Thanks.


...split from La Marzocco Linea Mini User Experience by moderator...

Sounds like your expansion valve is not adjusted correctly as you should not see pressures over 12 bar. Note that this is different than the brew pressure adjustment. Your brew pressure is set correctly since you see 9 bar when flushing the group.

Fortunately the expansion valve is super easy to adjust. See page 11 of the manual for how to do it: Linea Mini Manual

Congrats on your new Mini, it's a fantastic machine. Hope you enjoy it.

Thanks! I already did a full turn and it is still sitting a bit high over 12bar. The manual says it shouldn't be over 12. I guess I will turn it counter clockwise some more.

May I ask when you have the blind disk in doing a back flush, what's your gauge showing? I remember I adjusted the opv on my vibe pump VBM based on running a blank basket. Is rotate pump machines set the same way?

Sorry, my machine is on a timer and is off for the night. I can check tomorrow, but I'm pretty sure it shows 9 bar with the pump on regardless of whether it's a blind filter, puck, or nothing. But I can check tomorrow for you if you want.

Thanks so much for your fast reply. I am turning mine off too even though the dealer told me it's better to leave it on 24/7. I am not sure what's going on with the Mini today. With blank disk it shows 10 bar. Without PF just flushing it shows 9. I didn't think it'd make any difference though. Confusing.

For a rotary pump, pressure is adjusted directly via its bypass valve. The expansion valve simply limits the maximum pressure of the hydraulic system; it's typically adjusted to 12 bar.

IIRC.... here's my observations--
Brews at 9 bar
Recovery is always between 9 and 12
Idles at 12 or maybe a little lower
Back flush ramps up and stops at 15 within a few seconds

I'm pretty sure this is correct, but I'll double check tomorrow.

Phew, the expansion valve is easy to access but hard to turn. Without the proper tool it was quite a task to turn it. I finally got it down to idles around 11bar. Pulled a shot just to see and the gauge showed ramped up to just over 10bar. Hm....strange. It's bed time. I will leave the playing around until tomorrow morning. Thanks everyone for your help.

tlo wrote:Thanks so much for your fast reply. I am turning mine off too even though the dealer told me it's better to leave it on 24/7. ...

By the way, I happened to be in Seattle, so visited La Marzocco yesterday. The managers I talked to all assured me that the mini can be turned on and off as wanted with no problem. This is great as the heatup is so quick!

Here is a video of how my machine behaves when cycling the pump on and off a few times. As you can see it sits at 9 bar with the pump on and then when shut off rises to 12 bar.