Neue Dalla Corte Studio

Die 12 bar sind der Expansionsventil wert. Das ist völlig normal. Hat mit der Pumpe nichts zu tun.

 

Ah okay. Danke!

 

That's pretty normal. As the cold water reaches the tube in front of the brew head and extraction is finished, grouphead solenoid is closed on the one side of the tube while non-returned valve is closed on the other side (after pump), the cold water heats from the brew boiler (and from steam boiler, if enabled) and creates expansion pressure which is limited by expansion valve in manifold to 12 bar. Excessive water is then routed to waste water spout.

 

Yes pretty normal but, there could be negative point in case of next shot starts with 12 bar peak pressure. Im my opinion, release pressure after shot is much better for consistency of following shots and reliability of volumetric measurement. Any idea how to release pressure between pump and brew boiler?

 

Das hat nix mit Brühdruck zu tun, der wird nach dem Brühvorgang übers Magnetventil genauso abgebaut wie bei jeder anderen Maschine mit Brühgruppen-MV. Der Expansionsdruck entsteht ebenso bei jeder Maschine, die grade heizt. Er wird bei vielen anderen nur nicht angezeogt, weil das Rückschlagventil oft zwischen Expansionsventil und Manometer sitzt. Der Druck fällt schlagartig auf null, wenn sich das Brühruppen-MV zu Beginn des Brühvorgangs öffnet.

 

Sorry, i don not agree. After opening solenoid valve during shot, remain pressure (12bar) is going directly to brew boiler and coffee puck. Especially first phase of brewing period when ussually is PI, those peak pressure is releasing and should damage puck.... in my opinion

 

For pressure to press into something (the puck in our case) the system needs to be pressurized first, otherwise the air compresses and nothing presses on the puck.

So yea, this is funny, nothing is pressing on your puck before filling the headroom with water

 

Like Nobi said, once grouphead solenoid is opened at the beginning of the extraction, pressure is released to zero (or to line pressure I would guess, if Studio is connected to mains water suply). If you operate from water tank and you are that concerned about affect of volumetric extraction measurements, you can also delay the pump start by few tenths of second - the pressure will surely drop to zero for that short time before pump starts.

 

That 12 bar is expansion pressure of the water trapped inside between grouphead solenoid and non-returned walve, so very likely only few drops of water caused it due to very low water volume in tubing. And there is head room above puck at the beginning, like Denis pointed out.

 

Between grouphead solenoid and non-return valve there's also the brew boiler but nevertheless your argumentation is correct.

 

Yes, correct.

 

If system is overpressure by 12 bar, there is always risk to damage puck by releasing pressure through group head.
In pretty normal way is releasing pressure by head solenoid valve, same as many of espresso machine did. I saw this problem only in Studio.
Probably solenoid valve is close earlier than pump and this causing overpressure. Solution could be small delay between pump switch off and solenoid close. Fist should be pump off and several ms later solenoid valve.
Releasing pressure from system is easy (if using PI) just for second switch to 1 cup or 2 cups switch and no issue... pressure is zero or same as water connection
Can Dalla Corte solve this issue by SW? should be...

 

Are you interested in buying a DC Studio in the future?

 

I'm pretty sure, he already has one,

 

I don't think so, because the pressure is raising gradually after pump is stopped and solenoid closed, It must be expansion pressure of water heating and expansion.

 

Yes, Peter is correct I have Studio several days

 

I say it one last time: expansion pressure. Comes from heating the brew boiler. It is no issue It cannot be fixed. Every machine that heats a boiler has it. I'm doing this by profession for kore than 10 years now. If you don't believe me, ask anyone else her in the forum.

 

Yes this is 100% normal on machines that have the boiler mounted directly on the group. The manometer is reading the pressure in the whole group/boiler because they are connected the whole time.

One of my machines had this comportment, and it didn't bother me. once you press the start pump button the pressure goes to zero always.

If you look at the end of this video, you can clearly see the pressure building after I turn off the pump. At ~0:42 i switch the pump pff, no more flow in the cup, and you can see the pressure dial starts to go up. After a few seconds it goes up to 8-9 bar, so yes, no problem.

With this machine I pulled 25/26% extraction yield shots, so if there is channeling by the "build up " pressure this would not be possible.

 

Die DC Gummipuffer sind zwischenzeitlich ebenfalls eingetroffen. Sind etwas kleiner, aber genauso weich. Sollten genauso ihren Dienst tun, wie die von mir verlinkten.

Etwas zur Software 1.05c ist mir noch aufgefallen: Die Barista Lights liessen sich vorher ausschalten, waren aber beim nächsten EInschalten der Maschine wieder an. Das ist jetzt anders. Sie bleiben aus, bis man sie wieder per Menü reaktiviert, auch wenn die Maschine zwischenzeitlich abgeschaltet war. Wie es mit dem Zeitschaltuhr-Modus läuft (da wurden sie im Sleep-Modus nicht abgeschaltet), muss ich noch probieren.

 

I did not test the lights, but as far as I've found regarding the timer, it works only if it is enabled first and then the ON/OFF times are set. This is quite stupid, because once ON/OFF times are set (e.g. from previous day setting), it should work just by enabling the timer, but it doesn't and forced the user to go through ON/OFF settings again (just clicking through the times). This is necessary in view of when the timer is turning on (enabled) and off (disabled) as needed, i.e. not still in use.