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Interesting. It's definitely extracting a bit fast. Grinding finer just results in microchannelling and water spraying all over the place (with a naked portafilter). I'll try adjusting the pressure down a little and see how it goes.
My Expobar Minore is almost similar, just on 2 at rest, just over 4 when it is free flowing through the basket and just on 9.5 with a blind basket. So indeed the pressure valve needs to be adjusted down or you'll find the extraction a bit fast I guess.
Seems explainable to me. The pressure at the discharge of the pump is largely determined by the resistance to flow. With a blind, or a puck with sufficient resistance, the pressure will keep rising until it reaches the OPV set pressure (in your case 14 barg) and then stay relatively steady. Without an open basket, there is less resistance so the pressure stays low.
14 barg might be a bit high, but if you are reading 2 barg at rest, perhaps it's reading 2 bar over the true pressure?
My machine doesn't have a gauge, so I'm speculating a bit here, but it's consistent with my understanding of how the pump/OPV function.
I just bought a used Expobar Minore (manufacture date: October 2007). It's making decent coffee but I suspect the pressure gauge is reading wrong. When it's just sitting at rest it reads just over 2 bar. When it's free flowing with no basket it reads just under 4 and with a blind basket it reads just over 14. The machine is not plumbed. Does this sound screwy?
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