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La Pavoni Cellini Premium high pump pressure

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  • La Pavoni Cellini Premium high pump pressure

    Hi,
    I have a La Pavoni Cellini Premium and the guage on the group head reads 12 bar when there is a blind filter inserted.
    The machine doesn't have an adjustable pump, so I can't change it.
    Is this a problem, and will it lead to poor shots?
    Thanks

  • #2
    You only need 9 bars for good espresso. The 12 bar cutoff keeps the pump at or below 80% of it's rated 15 bar capacity which is good for its longevity.

    Should be perfectly fine.
    Last edited by CannotBePucked; 15 October 2019, 05:13 PM. Reason: Spelling

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    • #3
      Are you sure it doesn't have an Over Pressure Valve (OPV) that can be dialled down to 9.0 Bar?

      Mal.

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      • #4
        Thanks for the replies. I was talking to the technician where I bought it and he said it wasn't a commercial pump and can't be adjusted.
        To be fair I didn't really have an idea when I looked inside, but I couldn't see anything that matched the description. See photos.

        So, as long as my flow rates are good there won't be a problem, like overextraction, for example?
        Why is it that most machines aim for the 9 bar mark?

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        • #5
          A few more photos of the innards from different angles would help a bit more...

          Mal.

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          • #6
            It's got to have brew pressure adjustment somewhere. In a blurb I read on a website of someone selling them, it states that "9 bar is our company setting" implying that it's adjusted at the factory.

            On the machine, is there two tubes in the water tank? If so, one should go to the pump, the other would go to the brew over pressure valve which is the one you want to adjust.
            It's usually a T shaped brass fitting with a large flat head screw adjuster or a large nut. Turn it clockwise to increase pressure, anti-clockwise to decrease it.

            To set it correctly, you'll want it to show 9.5-10 bar static pressure when using the blind basket. This should yield around the 9 bar range when extracting.
            You can experiment with different pressures to see how it changes the taste.

            On a related note, I recently unboxed a brand new Bezzera BZ10 to bench test before sale. It was also extracting at an indicated 12 bar.
            I had to remove the case to access the OPV on this machine (pretty bad design to be honest) and turn it down. Shot quality improved after this.
            I suspect the retailer you bought your machine from did not perform this bench test which they really should have.

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            • #7
              Yep, was hoping that another photo would allow us to identify the OPV and walk him through the adjustment procedure...

              Mal.

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              • #8
                Ok so got it apart again and I can't really find the nut or screw.
                The pipe youre referring to from the water tank goes to a t piece. One side goes to the brass fitting in the first picture. The other side goes to the outflow end of the pump (3rd photo).
                Not sure if you can see with the photos I've taken but I'll just leave the case off it so I can get more specific photos if you need them.
                Thanks again for the help!

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                • #9
                  That is the same as the OPV in my Rocket Giotto, I pulled mine apart to adjust and then gave up as I needed coffee too much :-)

                  You can remove the rubber bit and then screw the nut in or out and test the pressure at group. There is a spring inside which lets water out (back into the tank I think) at certain pressures. I have a hunch it is adjusted by screwing the nut in/out which has the rubber fitting on the end. You would think logically that clockwise tightening would compress the spring inside thus increasing the pressure and anti-clockwise unscrewing would reduce the pressure.

                  If I am wrong someone please jump in and comment as I am interested.

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                  • #10
                    Yep, you hit the nail on the head!
                    Read your post just as I was doing some googling on OPV valves and I found one that looked the same.
                    Adjusted to 9 bar [emoji108]
                    Thanks

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                    • #11
                      Also, it's really annoying that the technician at Segafredo Zanetti in Coburg said it couldn't be adjusted...

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                      • #12
                        Very frustrating that technician must be lacking some technical skills. I recently did some work on a VBM Domobar Super I bought second hand which had "been fully serviced" by a coffee technician (with paperwork) and found the pressure running 12 bar, PStat about 1.5 and leaking from the E61 group which I had to pull apart, descale and replace most of the gaskets.

                        This one was really obscure as most machines have a nice easy accessible part which you can screw in/out with a flat screwdriver. I spent days googling different forums and YouTube videos but never found someone adjusting this style OPV.

                        I will just record here that my machine is a Rocket Giotto Premium Plus V2 so people can find this thread and know how to find and do the OPV adjustment.

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                        • #13
                          Also as Noidle22 mentioned you probably want 10 bar on the pressure gauge to run 9 bar at the group unless you are using a Scace or other portafilter pressure tester.

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                          • #14
                            This is a pretty commonly used OPV across a range of different manufacturers.
                            A bit fiddly to play with but looks like yours has plenty of room around it, so should be easy to adjust.
                            Once you have it set to where you want it, grab an indelible marker and draw a line across both components, so that you have a reference for any future requirements to adjust it.

                            Mal.
                            Last edited by Dimal; 18 October 2019, 04:49 PM.

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                            • #15
                              Sorry, I know this is an old thread that I am resurrecting. I have had this machine for a little under a year and have had a horrible time with channelling. I noticed the group pressure gauge reads 12.5 bar with the blind filter in, with coffee usually extracting at 11.8. Will lowering the OPV reduce my channelling? Anything else I can try? I have vst baskets, naked portafilter and fresh beans ground with a Eureka Mignon Specialita. Use an OCD and weight all shots using scales.
                              I also own a domus galatea that i use at work and have zero issues with extraction. The coffee is much nicer from that machine

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