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Thread: How adjusting my brew pressure fixed everything

  1. #1
    Senior Member gonzo89's Avatar
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    How adjusting my brew pressure fixed everything

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Greetings CSers (my first post after years, shame on me, it will be long to make up for it )

    Over the years I have read comments here and there on CS regarding brew pressure as a less important variable when diagnosing various problems with extractions. I am certainly not as knowledgeable on the subject as I wish I could claim to be, but what I want to share is an observation after years of brewing that might help others who have a consistent routine but want to experiment a little to see if they can get something better by adjusting their brew pressure.

    My previous machine (Bezzera D Galatea) gave me beautiful looking shots with the naked pf every time and without the need for an elaborate dosing routine. The result in the cup was superb, which is what matters most. After switching to an R58 in the last year I had to adopt other methods to get the extractions I was after (not plumbed in). The shots looked beautiful most of the time and the result in the cup is what I have been most satisfied with..but...on the weekend I started thinking, why do I need to grind so fine to get the result I want in the cup (burrs are fairly new but seasoned)?

    My taste buds must have changed or something because all of a sudden I started to lean towards the idea that I don't want my shots to be too sour anymore. I know that grinding too fine and only being able to work with a tight dose range is what is causing the sour shots but I couldn't lean away from that too much or my shots just didn't work. Also, I didn't want to have to use wdt to get a even extraction every time. I asked myself how can so many other members get away with a simple tap and tamp technique every time? Another part of me simply started to feel that I wanted a more balanced shot. Am I maturing on this wonderful coffee journey perhaps? Who knows.

    Now I am no stranger to experimenting with the more commonly changed variables (grind, dose, temp adjustments, distribution techniques, ratios etc). This time I just had an itch to play with my brew pressure. I don't have a proper gauge or anything but I let my taste buds guide me on this one and yes I did want to continue to see pretty shots, or better shots...Well, I wasn't disappointed .

    The R58 was previously set at 8 bar. A lot of beans tasted great and looked great using this setup for a long time. I would often adjust brew temp to hit the taste I wanted, but I'm sick of this setup. I pushed up the pressure to 9bar and the results since are,

    -MUCH prettier, thicker and slower extractions that look just as they should, like viscous honey.
    -I no longer require wdt in my routine. I tap a few times and tamp with the pressure I am used to and I get the same shots every time.
    -The result in the cup leaned away from sour which is what I wanted (I can drink the sour 'third wave' coffees that many members despise but I don't want to at home anymore).
    -Now my shots have so much more body, they are balanced in terms of acidity, sweetness and a blunt bitterness that is hardly there ( I don't enjoy bitter coffee). My shots now have this beautiful lingering finish leading to more pronounced flavours after tasting the shot. They also aren't so in your face upon touching the tongue.
    -When I adjust temps on the PID the result in the cup for different beans is more responsive in a positive way whether lower or higher.
    -One thing that changed dramatically was my grind setting on the Mazzer Major. 5 whole bars courser! This has given me the ability to play around with a much wider range of doses (I prefer between 18-21). The results are beautiful at any dose once the grind is also adjusted to suit.

    I apologise for the long post but I guess I wrote it like an account of what happened and I'm sure some of you will understand

    I also want to say that the whole not needing to use wdt for a pretty naked shot was truly confusing to me and often I wanted to blame the grinder, I was wrong. Ultimately, it's what is in the cup that matters and I am satisfied in many ways by the changes.

    Cheers Csers and I hope this opens up some discussions, comments and perhaps ideas.
    Al
    Last edited by gonzo89; 22nd April 2016 at 08:22 AM.
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  2. #2
    Senior Member iggs's Avatar
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    Great read! Glad you're getting the the results you want with much less fuss. I personally can't imagine doing WDT every time i wanted a coffee!

  3. #3
    Senior Member gonzo89's Avatar
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    Thanks iggs. I learned to deal with it because it gave me the result I was after. I guess I got jealous of all of you not requiring it at all

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    Something seems a bit odd here - you are grinding coarser, to achieve a higher pressure drop at a lower flowrate?

    I'm wondering if the capacity of the OPV was somehow coming into play (at lower pressures, the pump will flow at higher rates)?
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  5. #5
    Senior Member gonzo89's Avatar
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    Hi MrJack,
    Yes I believe you raise an important point about the OPV.
    I know I have changed the flow rate but I did not expect to be grinding that much courser. Most importantly though. With the courser grind I'm getting much more rounded shots but with just the right amount of enjoyable acidity in the shot. I'm not claiming to have done something original, just a story about how my tinkering led to a greater quality shot altogether and if anybody can add their expertise to the outcome by all means do

  6. #6
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    It is odd.
    The pressure comes from resistance (pressure drop) over the puck, which increases with flowrate and decreases with (increasing) grind size. So coarser grind should allow greater flow before reaching a higher pressure.
    The OPV operates by providing an alternate flowpath once the pressure reaches the setpoint - diverting additional flow away from the puck, and thus limiting pressure drop across it.

    However, if the additional flow is greater than that the OPV capacity at that pressure (that is to say if the pressure drop in the OPV flow path is greater than 8 bar), the flowrate will increase through the puck (raising the pressure).

    So perhaps a bigger OPV might have made a difference, even at the lower pressure? (I.e. flowrate is still the key variable, pressure being more of an issue w.r.t machine function).

    Just speculating here btw...
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  7. #7
    Senior Member gonzo89's Avatar
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    Although I have read a bit on the topic over the years I still haven't come to understand it in depth but yes what you are saying makes sense. I figured it may be a little too soon to see how this holds up with a variety of beans. After some additional tests today my current set of variables have been tested.

    The 3 different beans I was using at first all behaved in a similar manner (coincidence I guess). So I thought the courser setting might be there to stay with a wide range of beans. I ran through a Nicaraguan bean today (note: only 2 days post roast) and it brought my grinder setting back to where I was originally, 5 bars finer and I had to increase the dose to 22g.

    This hasn't been a problem though for 2 reasons:
    - the result in the cup is still excellent. A well balanced shot. I played with the PID a little to give me the taste I wanted.
    -I still did not require wdt and the extraction is even and pretty

    I will have to wait and see if I return to a coarser setting with different beans as I am stocked up for a few more days. I am keen to see how it holds up.

  8. #8
    Senior Member Yelta's Avatar
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    G'Day Gonzo, you say in your OP "My previous machine (Bezzera D Galatea) gave me beautiful looking shots with the naked pf every time and without the need for an elaborate dosing routine." the first question that comes to my mind is, why did you change from the Bezzera to an R58?

  9. #9
    TC
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    Good stuff Gonzo.

    Just keep in mind the influence of an assumption on which your experimentation was based.

    In the bench test which would have occurred at the importer before your machine shipped to the place of purchase, your machine would have been set to 9Bar via Scace device and that may well have delivered a gauge reading of 8Bar. System pressure gauges are notoriously inaccurate, so in all likelihood you actually started with 9Bar.

    Happy experimenting...

    Chris
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  10. #10
    Mal Dimal's Avatar
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    Also, doesn't the R58 use a Rotary Pump, not a Vibe Pump?

    That being the case, wouldn't you then use the Bypass Valve mounted on the pump itself to adjust the delivered brew pressure?

    Mal.
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  11. #11
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    Same thing really. An OPV is a bypass pressure control valve external to the pump.
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  12. #12
    Mal Dimal's Avatar
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    Yep, realise that Mr.Jack but it might cause confusion for people who don't realise this...

    Mal.
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  13. #13
    Senior Member gonzo89's Avatar
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    Quote Originally Posted by Talk_Coffee View Post
    Good stuff Gonzo.

    Just keep in mind the influence of an assumption on which your experimentation was based.

    Happy experimenting...

    Chris
    Hi Chris,

    That is something I failed to mention in my initial post and I wish to reiterate that yes I in no way can tell if what I am measuring is accurate.

    What I can take from the experiments is that even without an accurate reading of the brew pressure, I am going by taste and what seems to be working a lot better and I am quite pleased with the results. I have a sneaking suspicion that my tinkering has simply led to an optimal calibration without any certainty of what it is truly set at since the gauge cannot be relied upon for pin point accuarcy.

    The machine was serviced once and it was after that service I read on the receipt that they had recalibrated the pressure to 8bar. I didn't ask (I should have) if that was done properly or by looking at the gauge.. I now suspect it wasn't done properly.

    Thanks Chris
    Al

  14. #14
    Senior Member gonzo89's Avatar
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    Quote Originally Posted by Yelta View Post
    G'Day Gonzo, you say in your OP "My previous machine (Bezzera D Galatea) gave me beautiful looking shots with the naked pf every time and without the need for an elaborate dosing routine." the first question that comes to my mind is, why did you change from the Bezzera to an R58?
    Hi Yelta,

    I personally think the Galatea was much prettier although some won't agree.. My reason was that I wanted a dual boiler with PID.. I like to fiddle with temperature as a variable.
    Also, my partner likes lattes so I have the option of turning the steam boiler on and off depending on whether or not I am brewing for her.

    Call me crazy I guess
    Cheers
    Al
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  15. #15
    Senior Member Yelta's Avatar
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    Quote Originally Posted by gonzo89 View Post
    Hi Yelta,

    I personally think the Galatea was much prettier although some won't agree.. My reason was that I wanted a dual boiler with PID.. I like to fiddle with temperature as a variable.
    Also, my partner likes lattes so I have the option of turning the steam boiler on and off depending on whether or not I am brewing for her.

    Call me crazy I guess
    Cheers
    Al
    Thanks for the explanation Al, yep I agree the cosmetics of the Galatea ain't to everyone's taste.

    They certainly are an easy machine to get good results with.

    Pleased to hear you have R58 sorted out.
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  16. #16
    TC
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    Quote Originally Posted by MrJack View Post
    Same thing really. An OPV is a bypass pressure control valve external to the pump.
    Yes- the distinction in a rotary pump machine is that the bypass is normally set to a nominal 9Bar whereas you set the expansion valve to 12 bar- to protect in the case of a faulty bypass. Rocket Espresso actually do it with the vibe pump Giotto PID as well.
    Last edited by TC; 22nd April 2016 at 06:09 PM.
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  17. #17
    Senior Member gonzo89's Avatar
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    Behmor Brazen - $249 - Free Freight
    Yes Mal that is correct I adjust it via the valve on the rotary. Got to love the simplicity of just reaching under the machine to make the adjustment :thumbup:
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