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Thread: Brew pressure advice please

  1. #1
    Member SunnyCoastDazza's Avatar
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    Brew pressure advice please

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all, I picked up a used machine today. All functions as it should. I going through setting it up and found that it is hitting 8 bar running a blind flush.
    likewise whilst pulling a shot only slight over 8. Grind is not right yet as Iíve run out of time. Strange though the shots are tasting quite good for early stages.

    my question is. What brew pressure should I see whilst pulling a shot and with a bling? I thought I should expect to see 9 bar?

    thank you in advance. Iíve added a nice pic

    FCA2A29B-6162-49C1-B277-7DE805758F29.jpg

  2. #2
    Senior Member Lyrebird's Avatar
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    I'd question whether the pressure readings you are getting are accurate: assuming you are using the pressure gauge on the machine in the pic (VBM Junior?) it doesn't seem to be returning to zero so it's not likely to be reading correctly.

  3. #3
    Member SunnyCoastDazza's Avatar
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    Hmm the plot thickens. She’s a domobar super I set the pressure to 10 bar with the blind. Just pulled two shots and found the gauge is at 14 just when extraction starts then falls to 10 on the gauge. My thoughts are 10 at the gauge should be at around 9 at the group head. What I’ve read anyway. Or should I be looking for more of a consistent reading throughout the entire extraction?


    hold fire on this one. I think the issue is scale. Will report back in time
    Last edited by SunnyCoastDazza; 30th June 2019 at 08:26 PM. Reason: more info

  4. #4
    Member Martino's Avatar
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    Quote Originally Posted by SunnyCoastDazza View Post
    Hmm the plot thickens. Sheís a domobar super I set the pressure to 10 bar with the blind. Just pulled two shots and found the gauge is at 14 just when extraction starts then falls to 10 on the gauge. My thoughts are 10 at the gauge should be at around 9 at the group head. What Iíve read anyway. Or should I be looking for more of a consistent reading throughout the entire extraction?


    hold fire on this one. I think the issue is scale. Will report back in time

    Yeah, scale will screw up the process and when you buy a used machine, you never know. Before becoming too concerned with brew pressure, I would disassemble the brew group and inspect and clean and replace parts as needed. Then using the blind filter do a descale of the brew group so it cleans out all the channels inside and pull off the rubber or silicone gasket and strainer and clean them and if there is a way to do the same with the boiler, I would.
    Then you need to know if your pressure gauge is working correctly. So, using the blind filter like you would when descaling the brew group, turn on the pump and see where the needle goes and when the pump is off the needle should go to zero. Do this repeatedly and write down the results, like 10-12 times in order to check repeatability. If you believe the gauge is ok, then adjust the pressure to 8-9 bar, your choice. Do this by inserting the blind filter and turning on the pump and make your adjustment while the pump is running if you can, its just quicker. Again, check for repeatability. If you suspect your gauge is not right, replace it and then perform the procedure. You do not need more than 9 bar.
    Once the machine is set and repeatable, your next and more major job is to calibrate the grind setting while trying to achieve a consistent tamping pressure.



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