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Grimac Eclisse Pre-infusion

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  • Grimac Eclisse Pre-infusion

    There's been lots of debate about pre-infusion in machines, and how it's done and for long to do it.

    This is how it works on my commercial Grimac Eclisse, which may be of some use.

    Pump: rotary
    Water: tank (though normally plumbed in to mains)
    Brew pressure: 9 bar
    Idle pressure: 0 bar
    Controls: volumetric touchpads
    Valves: solenoid

    Once the brew touchpad is pressed, the pump shoots up pressure to 9 bar instantly. No ramping, no hesitation.
    Under 2 grams of water is released from the shower screen for under 1 second -- the time it takes for the solenoid valve to click on and off.
    The solenoid valve opens the group stem to release pressure to the drip tray and then immediately closes.

    In this cycle the pumps is still pumping.

    Water then resumes coming out of the shower screen at 9 bar for the remainder of the shot.
    That is approximately 30 seconds from the moment I press the touchpad to when the pump stops.

    So...is two grams of water for 1 second an adequate pre-infusion to saturate the puck? Probably not according to theory.

    Is pressure at 9 bar too much for a pre-infusion? You could argue that sort of pressure defeats the purpose of gently wetting the puck.
    However, with the portafilter removed and the machine cold, I've put my hand under the shower screen for both this pre-infusion and normal brew cycle and I can say there is no jet-blast force. It is all very gentle.

    How does the puck take it? Pucks always come out solid, well-shaped with no deformity (unless I screw up the dose).

    Note that the machine being volumetric, controls the brew cycle according to how much water has gone through the inline flowmeters. Not according to how much time has elapsed.

    A digital battery clock clipped to the warming tray tells me timing. Not the machine.
    Attached Files

  • #2
    Originally posted by robusto View Post
    There's been lots of debate about pre-infusion in machines, and how it's done and for long to do it.


    This is how it works on my commercial Grimac Eclisse, which may be of some use.


    That's quite different from the E61's built in mechanical pre-infusion. One thing that seems to be overlooked or often misunderstood is that any machine with an E61 style grouphead has mechanical pre-infusion by default courtesy of the pre-infusion valve. As the water is pumped into the E61 grouphead, the pre-infusion valve opens at around 4 bar allowing lower pressure water to wet the puck until the pre-infusion chamber fills and pressure then builds to the full 9 Bar for Brewing. This can be observed on the Brew Gauge of an E61 machine while Brewing. I believe the original concept was to help reduce channeling in the puck by wetting/expanding it with a gradual pressure build-up.

    Click image for larger version

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    • #3
      Very tidy setup there Robusto...

      I think the importance of 'pre-infusion' has more relevance to machines that use rotary pumps rather than vibe pumps. Vibe pumps tend to build up pressure quite gradually as a feature of their physical limiting factors - Ideal for most prosumer machines.

      There are other mechanical means of creating a gradual pressure buildup with rotary pump machines of course without recourse to using electronic means such as that used by E-61 groups, the inclusion of small accumulator like devices before the group. I think anything that allows for the gradual pressure buildup on the coffee puck is generally, a good thing and most manufacturers have incorporated their own designs into their machines. Simple is always best though...

      Mal.

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      • #4
        Ive got a Grimac Mia and buttons look very similar to your Eclisse, but Mias got the vibe pump so works kinda different but sounds the same,
        You don't recall how to program your buttons by any chance Robusto?

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        • #5
          You program the Volumetrics on a Mia by holding the manual button (* on the top left of the pad) until it flashes.
          Then start the shot with the single or double button, stop it by pressing the same button again and voila, it's programmed.

          Peter

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          • #6
            Originally posted by pjchris View Post
            You program the Volumetrics on a Mia by holding the manual button (* on the top left of the pad) until it flashes.
            Then start the shot with the single or double button, stop it by pressing the same button again and voila, it's programmed.

            Peter
            oh cool thanks Peter, after refurbing the mia I figured itd be something simple, now to adjust the spacex launch delivery milk steaming, boy that things got power!

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            • #7
              Yes, what Peter said.

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              • #8
                thanks lads all reprogrammed cheers

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