Confusion with OPV adjustment, Rocket Cellini V2

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Slim Phatty

#1: Post by Slim Phatty »


I've tried adjusting OPV in my Rocket Cellini V2 machine for 9 bars, but it seems it's more complicated that I though it would be. Before doing anything, I checked blind basket reading from brew pressures gauge and it reads 10,5 bars without factory settings. I would like to get the brew pressure closer to standard 9 bars. So, I adjusted the OPV valve (marked with red arrow) to counter clockwise 1/2 turns, but there's no difference in gauge reading after that (it's still 10,5 bars).

Then I discovered this thread that discusses exactly same topic and it mentions that there's a separate black level that should be turned when doing the adjustment. Should I turn it first and then do the OPV valve adjustment, or the other way around?

OPV on Rocket Cellini V2 is confusing.




#2: Post by JRising »

Your red arrow points to the OPV that is functioning as an Expansion valve.
Your blue arrow is pointing at the OPV that limits the pressure the pump is putting into the system.

With the ball valve closed, please re-adjust the expansion valve back up to about 12 so that it won't be affecting the flow when brewing, but it will be relieving the thermal expansion. (The ball valve needs to be closed so that the pump can get enough pressure into the brew circuit to see what the expansion valve is set to).
Once the Expansion valve is set, open the ball valve to see what the pump's OPV is set to, and adjust it as desired.

I hope this makes sense.
★ Helpful

Slim Phatty (original poster)

#3: Post by Slim Phatty (original poster) »

Thanks for the advice, Is the ball valve open by default factory setting (current position in the picture) ?

I readjusted the expansion valve (red arrow) to same position it came from factory, so the steps to set up my machine to 9 bars would be the following?

1. Close the black valve (blue arrow)
2. Adjust expansion valve counter clockwise (since brew gauge was displaying 10,5 bars with default settings)
3. Assemble water reservoir steel mount back and put water tank back
4. Turn on the machine
5. Check reading with blind basket
6. If reading is correct from brew gauge, I turn ball valve back to default position (blue arrow) after machine is cooled down ?

If the reading is still too high, do I just reassemble and adjust the expansion valve (red arrow) until it reads 9 bars from the brew gauge?


#4: Post by spopinski »

Expansion safety valve needs to be set to 12 bar. So you need to tighten the brew opv first ideally higher than 12 bar, so it will be high enough to adjust the safety valve. After you reach the 12 bar reading then you can adjust the brew opv.


#5: Post by JRising »

Slim Phatty wrote: 5. Check reading with blind basket
6. If reading is correct from brew gauge, I turn ball valve back to default position (blue arrow) after machine is cooled down ?
In the photo the ball valve is open, so the pump's OPV is "In Use". The pump's OPV is the lower setting, perhaps 9.5 bars. You have to close the ball valve to prevent that (blue arrow) valve off from the circuit. Running the pump with the ball valve closed and the blind basket in place will force the water over the other OPV, the expansion valve which is now the only OPV in the system (with the ball valve closed) so it is now relieving the water from the pump. You can set it to 12 this way.
Then once you open the ball valve, the blue arrow OPV is back in play and it will be relieving the pump's overpressure and you can adjust it to your 9 or 9.5.