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Thread: optimum pressurestat setting

  1. #1
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    optimum pressurestat setting

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I have a thermocouple permanently installed in the top of each group leading to a digital thermometer....and with these, it is easy to start each shot at the desired temperature.


    Using the thermocouples, I have set the pressurestat to turn off at 0.9 bar which brings the idle temperature measured at the thermocouples to a touch less than 95C. It is easy for me to do a cooling flush to prepare the upcoming shot to the desired temperature.....but maybe there is a "better optimum" that I can achieve with the Futurmat.

    I would like to set the pressurstat on my 2 group to give me the best compromise between "waiting to heat-up times" and "reduced cooling flush size".


    Does anyone have any advice on how to do this?

    (Realistically, I have the machine turn on on a timer each morning. I shut it down after it does its morning magic and light the wick again in the afternoon for more magic. I rarely have the machine going all day.)

    Thanks,
    Paolo.

  2. #2
    Senior Member robusto's Avatar
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    Re: optimum pressurestat setting

    Not sure I understand what you are trying to achieve Paolo "waiting to heat up". Do you mean from stone cold? Or, having pulled a few shots, waiting to heat up for the next one?

    Your 0.9 bar giving 93-95 is a good setting, though I find 95 a tad on the hot side.

    My view is that you should set and forget the pressurestat once you have achieved your desired temperature.

    You can experiment with more or less boiler water level so that more or less of the heat exchangers are immersed.

    But again, Id fill to the manufacturers recommended level, set the pressurestat, and do the temperature tweaking by coolish flushes only.

    -Robusto

  3. #3
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    Re: optimum pressurestat setting

    Hi Robusto,

    I dont want to alter the boiler levels.

    From 95C I need to do a cooling flush. My favoured brew temps so far lie in the 93-94C range.

    Indeed, Robusto it is the "from stone cold" that I am referring to.

    If I tweak the pressurestat even more, I might be able to achieve an idle at my favoured zone (93-94C) but maybe the warmup time (and steam production) will be compromised.

  4. #4
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    Re: optimum pressurestat setting

    Robusto,
    The "waiting to heat-up" time that I spoke of also refers to the recovery rate ( temp) in time after a cooling flush.

  5. #5
    Senior Member phil_jeffery's Avatar
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    Re: optimum pressurestat setting

    Hi Paolo,

    In my limited experience, I think that boiler level appears to have a greater effect on group temperature than boiler pressure. I set the P-stat to about 0.9 Bar max., then adjust the water level upward until the steam is coming out wet and spitty. I then back it off until I get the fastest recovery without getting too hot. This has been at a different level with the 3 machines I have tried it with, so its certainly machine dependant.

    Come to think of it, I have been meaning to alter the level of my current machine but have been too lazy to pop the cover; I might make it this mornings task!

    Where have you located the thermocouple in the group? It sounds like a good idea that I should adopt... it never ends, does it?!

    Regards,
    Phil

  6. #6
    Senior Member robusto's Avatar
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    Re: optimum pressurestat setting

    Paolo, Ive never had a problem with recovery after brewing or steaming. There is more than enough heat and steam available for successive shots -- thats what commercial machines do.

    As for start up -- I dont think that increasing pressure is going to achieve much, if anything. Increasing pressure slightly will only raise the temperature a degree or two, but that element will still cycle on/off.

    If you find waiting for the machine to stabilise is inconvenient, leave it on all day during waking hours. No harm in that -- it was designed to be left on.

    -Robusto


  7. #7
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    Re: optimum pressurestat setting

    Hi Phil,
    If you look on this Coffeeparts link
    http://www.coffeeparts.com/futurmat/fut1.html
    you can see a hex cap above part #524554.

    I have an adaptor that allows a thermocouple of the correct length to sit just in front of the hole that feeds the brew water to the dispersion screw in the group.

    It works beautifully.


  8. #8
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    Re: optimum pressurestat setting

    Robusto,
    I would be more interested in lowering the boiler pressure to bring the idle temperature closer to brew temperature...so that not much of a cooling flush is necessary.



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