Thanks for all the continued feedback and interesting information, everyone. Also glad (sort of) to hear I’m not alone.

DavecUK, this happens even when using no preinfusion of any kind, and also with steam boiler off and cool.

    I will keep an eye on mine. I never noticed this. But then again, I only have one coffee in the morning, and one in the afternoon. If there’s any testing I could do, please just let me know. 👍

    Pygmalion If that is the case, I can only assume it must be a transient water hammer effect type of thing due to air? I would expect it to have no impact on the shot.

    Any chance of video of it doing it?

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      Hi, all. Here is a video showing the inconsistent pressure with the blind basket. There are three shots total here about a minute apart:

      Here is another one that just shows a single shot with coffee, showing the initial spike, subsequent drop, then slow decline. But, the pressures here are generally above what the blind basket shows after a few shots on the first video.

      Also, here is a video made by someone else showing very similar behavior to mine (found on a different forum):

      DavecUK: if it is due to some air somewhere in the system, do you think it would be possible to bleed it out somehow?

        Thanks for the offer to experiment, @MediumRoastSteam!

        Here is a simple experiment you could try. Turn on your Elizabeth and allow to come up to full temp without running the pump at all. Insert blind basket into the portafilter and then engage the pump with no preinfusion (may or may not matter). Watch the pressure reading. Does it spike and then settle, or does it move to a consistent value? What value? Then disengage the pump and wait a minute or two for the system to read OK and temp to maybe rebound. Then repeat. Does the pressure behave the same way as the first time, or does it settle to a different value?

          Pygmalion DavecUK: if it is due to some air somewhere in the system, do you think it would be possible to bleed it out somehow?

          Probably not and with coffee in I am surprised the effect was as sustained as it was unless the coffee was quite a tight grind. Also when I say air and water hammer, I would expect the effect to be very transient. Air itself compresses to feck all at 9 or 10 bar….which would cause the hammer and can be fairly quickl;y absorbed at those pressures..

          In your first video, what happens if you repeat the experiment, but fill the blank portafilter basked with cold water and carefully lock it into the group, spilling as little as possible.

          Otherwise I’m mostly out of ideas.

          • could it be a sticky expansion valve (I don’t think so), unless there is a manufacturing defect? But it still doesn’t explain why after a shot or two the problem always goes away.
          • Some weird water heating expansion effect (but that doesn’t fit with the way the Hydraulics are connected.
          • Some fault on the gauge but then why does it self correct after a few shots?

          Nope I’m a little stumped. We can eliminate heat effects, if someone wants to disconnect the brew boiler heating elements, turn the steam boiler off then repeat the blind basket experiments.

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            Pygmalion Here is a simple experiment you could try.

            Done!

            The temperature was at 96C because it was on at the end of the heat up cycle towards 93C. For the sake of the experiment, on the subsequent shot, I have set the temp to 96C, let it get here and set it back to 93C.

            On the subsequent shot, I emptied the blind basket before starting, so both are from the same starting point. They were taken approx. 7 minutes apart. I also did one with the basket full of water, and the behaviour is the same overall, with the exception that, as expected, it reaches the target pressure faster.

            When using coffee rather than the blind basket, the behaviour is the same, but the pressure gradually goes down to approx. 8.75 bar on the dial over the course of 35 seconds, as expected.

            From cold:

            7 minutes later:

            This is an older video where it shows a coffee pour. This was when the Elizabeth’s pressure was set at 10 bar. But you can see the behaviour of the gradual pressure reduction. These days is the same, but at 9 bar or thereabouts.

            With coffee (older video):

            Hope the above is helpful.

              I pulled a shot with no PI, it went to 11 bar then gradually decreased to approximately 9.5 until the end of the shot. I filled the blind basket to the brim with cold water and hit button 1 again (no PI), it went up to 11 bar and stayed there until I stopped the shot. Is it that the opv is tuned to 11 bar (in my case here) and simply reduces as the puck gets extracted? I don’t see an issue really or is this different to the OP’s issue? I had noticed this recently but didn’t worry, as the coffee still tasting great

                JahLaza pulled a shot with no PI, it went to 11 bar then gradually decreased to approximately 9.5 until the end of the shot. I filled the blind basket to the brim with cold water and hit button 1 again (no PI), it went up to 11 bar and stayed there until I stopped the shot. Is it that the opv is tuned to 11 bar (in my case here) and simply reduces as the puck gets extracted?

                If this is the consistent behaviour, it could indeed be that your expansion valve pressure needs reducing, try reducing it to 9.5 bar against a blind filter and see how you get on.

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                  JahLaza - what you are describing is absolutely normal and it is what you see on my videos, albeit at a lower pressure.

                  It’s not, however, what @Del_UK and Pygmalion are experiencing.

                      Yeah, ok, thanks both. I wonder if there’s any need to reduce it at all? I had read somewhere the difference between 9 and 10 bar isn’t worth talking about would you advise to reduce it a bar or so in my case?

                        JahLaza would you advise to reduce it a bar or so in my case?

                        Try it, it’s very easy. Only your taste buds will tell. 😊

                          Thanks for running the experiment, @MediumRoastSteam ! Glad yours is working normally.

                          I tried the experiment with the blind basket initially full of water, and the behavior was still there with no notable change except for attaining pressure sooner, as expected.

                          I have opened a ticket both with my reseller and Lelit directly, to see if they can assist. But in the meantime, if anyone else has any theories I’d love to hear them.

                            Reduced it to 9.5bar with blind filter (yes it was a very easy action!) just pulled a shot, it still went up to 10.5 bar at start of shot but maintained about 9.5 bar from about 13 secs. Tastes great, not sure if there’s a difference, fuller body I think maybe. Apologies if I’ve slightly diverged from the thread topic folks, interesting all the same🤔

                            Pygmalion I think I have the same issue as yourself. When I run first cycle with blind basket it hits 11 bar before slowly falling down towards 9.

                            Subsequent cycles go straight to 9 and hold. I tried filling the basket with cold water and that one goes straight to 9 bar and holds there.

                            I will pay attention to tomorrow mornings shots to see what is happening with coffee in the basket. I never look at the needle - watch start of shot then fill my milk jug whilst it’s pouring.

                            Niche Zero

                            Niche Zero

                              @MediumRoastSteam I use self-made remineralized water. It is 70/30 water: distilled water with a tiny bit of baking soda and Epsom salts added according to the recipe here:
                              https://s3-ap-southeast-2.amazonaws.com/hosted.fivesenses.com.au/hosted_docs/water_recipe.pdf

                              Interesting results, @Ando . It seems like your behaves normally when the blind basket initially contains water, though, while mine didn’t behave any differently in that scenario.

                              • Ando replied to this.

                                Pygmalion If I leave my machine for a while, fill blind basket with cold water - it overshoots to between 10 - 11 and slowly drops from there.

                                Everything following this first one goes straight to 9 and stays there.

                                If this is normal then grand. But it does seem very similar to what your videos were showing

                                Niche Zero

                                Niche Zero

                                  Ah, I see @Ando - I misunderstood. Sounds like yours is behaving similar to mine then.

                                  I also am ok with all this if it is normal and isn’t affecting the coffee. But, it doesn’t sound like it is especially normal, given that at least @MediumRoastSteam’s machine doesn’t seem to do this. I also worry that, since it definitely does this for me with coffee too, my initial shot of the day will end up being significantly different than subsequent shots, given that it will be at notably higher pressure than the others. Also, if it is indicative of some sort of flaw in the machine, then that just means a potentially more likely failure down the road, which I’d like to fix now while under warranty.

                                  Curiosity got the better of me and turned machine back on to pull couple of shots with coffee.

                                  First one touches 10.5 bar when machine ramps up (no PI) and is just under 9 at the end of the shot.

                                  Second shot made straight after only goes to 9 before beginning to drop down to 8 by end of shot. This was 2 secs slower than first one.

                                  So consistent with what was happening with blind basket tests.

                                  Something to be concerned about?

                                  I do struggle to dial in a lot of the time and get consistent shots that take same time etc.. I always just put it down to my inexperience or some other reason however …

                                  Niche Zero

                                  Niche Zero