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Thread: Silvia Temperature Stability

  1. #1
    KJM
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    Silvia Temperature Stability

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Ive measured the brew-temperature stability of my PID equiped Silvia. *The attached graph shows the in-puck temperature of the coffee. *I did this many times (this is a very messy undertaking!). *

    The data is from a cold start, run up to temperature (< 5mins, I didnt time it); run a double shot of water through; wait till it is hot again; run another double of water; grind, tamp, lock and load, wait till it is hot again and then run.

    This regime gives identical temperature profiles to leaving the thing on for a couple of hours and then pulling a shot. *So a Silvia can pull a shot in "next to no time".


  2. #2
    KJM
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    Re: Silvia Temperature Stability

    Darn - forgot to add. I hope to repeat this experiment with my Sisters Silvia (non-PIDd). Will post some measured data when I get it.

    Note to anyone who wants to do this : get a waterproof laptop cover!

    /Kevin

  3. #3
    Senior Member greenman's Avatar
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    Re: Silvia Temperature Stability

    Good effort, did you have the PID set on 109C mark?

  4. #4
    Mal Dimal's Avatar
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    Re: Silvia Temperature Stability

    Great info Kevin.... 8-)

    Discovered a similar but slightly tighter performance curve for a Mokita a few years ago after I installed a PID controller. Probably one of the most worthwhile things one can do with a Dual Purpose/Single Boiler machine of this type. There is also the added advantage of being able to walk up and pull a shot without any fuss and terrific steam pressure control too for producing perfect microfoam every time.

    Sometimes miss the little Mokita.... ::)

    Mal.

  5. #5
    KJM
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    Re: Silvia Temperature Stability

    Greenman - the PID setting is 107C for my machine. This is probably machine specific - itll depend on mounting position of the sensor and other things...

    Mal - I cant see how I could make the profile tighter, without doing crazy things. Like pre-heating the P/F handle. The two flushes through basically heat it up nicely - the 4 odd kJ specific heat of water is very effective!

    One thing to note: the temperature is the temperature of the puck - the probe is not sitting on the top. The input water temperature is much more stable. (Well, the measured temperature dips second crack and the water dips under first crack).

    Interestingly - if I run 220ml through (the capacity of the late glasses I have ::) ) then the temperature glides down after about 100ml - it drops smoothly to about 85C (from memory). The machine definitely has more capacity than the web-opinion would imply.

    Ill try to take some measurements on Hazbeans HX machine in a week or so when he returns from his mini-holiday and compare the stability.

    /Kevin

  6. #6
    Mal Dimal's Avatar
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    Re: Silvia Temperature Stability

    Quote Originally Posted by KJM link=1228716026/0#4 date=1228809219
    Mal - I cant see how I could make the profile tighter, without doing crazy things. Like pre-heating the P/F handle. The two flushes through basically heat it up nicely - the 4 odd kJ specific heat of water is very effective!
    Sorry mate,

    I wasnt trying to insinuate that my PID mod was better than yours, just different. I think the tighter control is due solely to machine design, nothing that I did. With the Mokita, the Boiler sits directly on top of the Group whereas the Silvia has an intervening adaptor section between the Boiler and the Group. I also set up the controller, coupled with the location of the t/couple, so that a pseudo "feed-forward" element was introduced. This just suited the way I wanted to do things, thats all..... :)

    Mal.

  7. #7
    KJM
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    Re: Silvia Temperature Stability

    Mal - I never read your post that way. I know the differing configurations of boiler position with respect to group head do change things, but the PID is probably a furphy in all this. The PID just gives you the water supply at a precisely controlled state. This helps (absolutely!) in getting the right temperature at the puck, but the physics of the machine basically give you the stability.

    Which makes me wonder if there isnt a part of the espresso machine design space that hasnt been explored. All the machines youd want to buy have mountains of brass in the head etc for stability. A heretical design might be to have almost zero thermal mass in the portafilter/head and then the water becomes the only significant factor. (Hmmm - smells of burning heretic suddenly around here!)

    Cheers
    /Kevin

  8. #8
    Mal Dimal's Avatar
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    Re: Silvia Temperature Stability

    Sounds interesting Kevin..... ;D

    I think you and "Sparky" should get your heads together to see what you can come up with. I seem to remember Mark postulating a similar "heresy" a couple of years back ::)

    Mal.



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