Measure and understand the pressure on a Pavoni

Controlling and understanding the water pressure in your coffee machine is important in order to successfully extract it. This parameter is completely controlled on automatic machines while it is less on a manual machine such as the Pavoni. Some knowledge can help to better understand and better control the water pressure when using the Pavoni machines. In my article, I will especially talk about the pressure exerted on the piston when you press the lever.


Water pressure in the boiler

Some models of the Pavoni are equipped with a manometer. This allows according to the pressure to estimate the water temperature. The documentation indicates that the boiler pressure must be between 0.6 and 1 bar. The water will be about 94 °c. I explain this much more precisely in the following articulation.

La Pavoni manometer. The manufacturer recommends carrying out the extraction in the green zone of the graduations.


Mesurer la pression de l’eau dans le piston d’une La Pavoni

The water pressure in the plunger has an important influence on coffee extraction. I became interested in the subject and found several methods to measure this pressure.


Method 1: Convert the force applied to the lever in bar

La première méSome models of the Pavoni are equipped with a manometer. This allows according to the pressure to estimate the water temperature. The documentation indicates that the boiler pressure must be between 0.6 and 1 bar. The water will be about 94 °c. I explain this much more precisely in the following articulation.

To know the force applied to the lever of the coffee machine, there is nothing simpler: just put the machine on a scale.

The mathematical formula to use is available here. However, to make reading easier, a user of the home-barista forum posted a chart.

Graph for converting the pressure of the lever to water pressure in the piston

On professional machines, it is recommended to extract the coffee with a pressure of 9 bar. According to the graph, on a Pavoni, to obtain this optimum pressure, a force of approximately 13.7 Kg must be applied to the lever.

You can do some testing and then estimate if you apply a comparable force on the lever during your checkouts.


Second method: Install a manometer on the piston

Another (more costly) method is to replace the piston to allow instantaneous measurement using a manometer. If you are interested in this method, you will find user feedback on the Internet. Personally I find the rendering pretty, but at $300, well too expensive. The kit can be bought here.


Third method: doing a DIY

I discovered by chance a method much more hardcore (but precise and less costly). Always on the Forum home-barista A user to pierce the piston to attach on the side a manometer. The rendering is a bit weird, but ergonomic (when you press the lever one is on the side of the machine then the manometer is well facing the user).


Conclusion

In conclusion, to properly master a coffee extraction with a coffee machine La Pavoni, you must remember the following things:

  • The boiler pressure must be between 0.6 and 1 bar.
  • Leave the machine on long enough for the machine to be hot (some talk about 20 minutes, but personally I leave it on for less time and I have good results).
  • Grind his coffee, pack it…
  • Open the steam valve for a few moments to let the fake steam escape
  • Lift the lever to allow a little water to flow. This step allows you to heat the piston to the right temperature, remove the coffee residue from the previous extraction.
  • Place the filter holder (if using a spout filter holder, it must be heated before, as is the cup).
  • Lift the lever, do the prebrewing (I do 6 to 7 seconds of prebrewing)
  • Lowering the lever by applying approximately 13.7 kg of force, extraction must be between 25 and 30 seconds (with prebrewing)
  • Enjoy your coffee:)

15 comments

  1. We purchased our machine about a month ago. The coffee tastes great but…
    When we raise the handle it falls back down again, so absolutely no “pressure” or resistance.
    Any ideas, anyone?

    1. It has to come from coffee. If the coffee is too old, the water will pass without resistance. Also, it is necessary that the coffee is ground quite fine and in sufficient quantity. To give you an idea, I grind very fine 16 g of coffee per coffee. But often other people go up to 18g.

  2. Thomas

    Really appreciate your thoughts. Our coffee is fresh and ground on an as-needed basis, to a fine grind.

    Our issue is that the we have some resistance when raising the handle, none to hold it up, or when being lowered.

    Do you think that this is because the machine is not working as it should?

    Hamish

  3. Hi I have a brand new La pavoni Cellini Evolution and my boiler pressure gauge is Lower than 0.5 is that a normal thing? How do I raise it

  4. The pressure guage keeps going into red zone at speed so I turn off machine as am worried about the machine exploding. Is it dangerous to use. Also the water level in glass water level moving around rapidly with the pressure rising. Thank you

  5. I purchased an older La Pavoni at auction. It has a Minimo/Maximo switch. Also it seems that the pressure is too great. It is almost impossible to press down. I’m afraid it is going to explode!
    Can you tell me the proper way to use the switch? I’ve googled everywhere. Any help would be appreciated. Thank you!

  6. Lois,
    The low heat setting is intended for heating the water and machine. The high position is for making stream. Even so, I use the high setting when I’m in front of the machine, and want it to heat quicker.

    If left on buy itself it can easily boil dry and then trip the cut-out in the base. I think later model machines have a thermostat built in. I can’t leave mine on for long periods on either setting, but the high one is worse of course. Dave

  7. I have a La Pavoni Esperto with a pressure gauge on the group head. Honestly, it’s hard to go past 6 bars. I get great coffee at that pressure, and I do get 32 g out for a 16 g in, in 30 seconds, pre infusion included. If I try to get 8 or 9 bars, it is hard enough that my wife couldn’t do it. And anyways, the whole machine is bending under pressure. And the group head gasket is whistling a bit. It looks like this machine is MADE for a 6 bar extraction. Again, I’m not complaining, the taste is great. I’m just fetching for your opinion here.

    1. the problem probably comes from the coffee used. Are you sure the coffee is freshly roasted? How much coffee do you put in the machine? also, do you use a coffee grinder dedicated to espresso to grind the coffee before extraction?

      1. Yes, Tanzania Peaberry, roasted 6 weeks ago. Hand grinded, Kinu grinder position 084. 16 grams in, 32 grams out. I have been using this exact grain for a year now. That grain, and every grain in fact, give me this exact pattern. I get a very good extraction, in due time, with due pressure on pulling the lever, but it seems that the machine WANTS me to work at 6 bar. I’m not really complaining, as the result is perfect. I’m just curious… is a La Pavoni MADE to behave this way? Maybe so.

        1. you are well equipped. no worries on the coffee side.
          maybe the problem comes from the La Pavoni window piston?
          Is your machine old? sometimes the piston seal is worn and the pressure is no longer the same.
          In my case I don’t have this problem.

          1. Curious: do you have a La Pavoni with a pressure gauge on the group head? If so, what reading do you typically get (I’ll leave you alone after this question, promised)

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