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Re: [John Muir Trail] Re: Jetboil

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  • John Ladd
    Cool. I was wrong. Peter s results are quite close to my field experience. I ve tended to run my JetBoil at about what he describes as his medium flame or a
    Message 1 of 42 , Dec 17, 2012
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      Cool. I was wrong. 

      Peter's results are quite close to my field experience. I've tended to run my JetBoil at about what he describes as his "medium flame" or a bit higher, though at times I've used the full flame under the belief that the JetBoil was equally efficient at either setting.  I've tended to use about 10  grams of fuel per day making two meals of about 16 ounces each.  This has been pretty stable across multiple trips.

      If sounds to me like Peter's nailed this issue.  Looks like it's best to use a JetBoil at a vigorous flame, but not literally at full flame.  Given the boil time results in his test, looks like his medium setting is in the vicinity of 80% of full possible heat output, which sounds about right to me. I suspect (though I can't really prove) that one could do a bit higher flame than that before starting to lose much efficiency. This is way less scientific than Peter's testing. I'm just judging by the heat loss I can feel buy putting my hands alongside the pot as it's cooking.  You can run it pretty close to flat out without feeling much heat loss along the sides, but I have noticed some heat leakage at full blast.

      John Curran Ladd
      1616 Castro Street
      San Francisco, CA  94114-3707
      415-648-9279



      On Mon, Dec 17, 2012 at 11:14 AM, <pburke@...> wrote:
       



      --- In johnmuirtrail@yahoogroups.com, pburke@... wrote: >
      > I am curious, though, if the SOL performs better at higher flame
      levels, since the Helios clearly gets by on less fuel at the lower
      level. Maybe this weekend...
      >

      here are the results - I did three levels of flame.

      setup for each run:

      JetBoil Sol Aluminum pot, about a year old, used for a total of about 8
      gallons of hot water since purchased. Each test performed with 0.5
      liters of tap water (about 60F), almost new canister of Gigapower 110g
      fuel, indoors at room temperature. I cooled down the pot between each
      run, made sure the canister remained warm for even pressure. cozy on
      cup, lid closed. Time take once rolling boil was established.

      First run - setting at max - turned the flame up until I didn't see any
      change in size or noise

      boil time 1:49 mins

      fuel used 5.5 grams

      Second run - setting "medium" - nice large stable flame, but well below
      max setting

      boil time 2:12 mins

      fuel used 4.3 grams

      Third run - minimum setting - flame as small as it could be set without
      flickering and looking like it would cut out

      boil time 4:38 mins

      fuel used 4.4 grams

      Bottom line - somewhere in the middle is where you want the flame to be
      to save fuel. Going super low doesn't save fuel, just taks longer and
      risks the flame being blown out by wind if outdoors. However, the myth
      that the Jetboil is most efficient at max flame clearly doesn't apply to
      my stove.

      Maybe I should repeat the test with ice water and in cold outdoor
      conditions, but I doubt the result will be much different. I think the
      small flame doesn't work very well because it doesn't reach the heat
      exchanger fins on the cup, while once you reach those, you're good. Any
      more flame may just leak heat beyond the fins, which is then seen as
      wasted fuel. The full blast run used 27.9% more fuel than the medium
      setting. Over 8 days, boiling 2 liters of water each day, this
      difference still not really important, since at max flame you'd need 176
      grams of fuel, while at the efficient setting you're using 138 grams. In
      both cases, one 220gram canister will get you there, while a single 110g
      is too small. If you boil more water or pack for longer trips without
      resupply, it can save you an extra canister.


    • John Ladd
      Cool. I was wrong. Peter s results are quite close to my field experience. I ve tended to run my JetBoil at about what he describes as his medium flame or a
      Message 42 of 42 , Dec 17, 2012
      • 0 Attachment
        Cool. I was wrong. 

        Peter's results are quite close to my field experience. I've tended to run my JetBoil at about what he describes as his "medium flame" or a bit higher, though at times I've used the full flame under the belief that the JetBoil was equally efficient at either setting.  I've tended to use about 10  grams of fuel per day making two meals of about 16 ounces each.  This has been pretty stable across multiple trips.

        If sounds to me like Peter's nailed this issue.  Looks like it's best to use a JetBoil at a vigorous flame, but not literally at full flame.  Given the boil time results in his test, looks like his medium setting is in the vicinity of 80% of full possible heat output, which sounds about right to me. I suspect (though I can't really prove) that one could do a bit higher flame than that before starting to lose much efficiency. This is way less scientific than Peter's testing. I'm just judging by the heat loss I can feel buy putting my hands alongside the pot as it's cooking.  You can run it pretty close to flat out without feeling much heat loss along the sides, but I have noticed some heat leakage at full blast.

        John Curran Ladd
        1616 Castro Street
        San Francisco, CA  94114-3707
        415-648-9279



        On Mon, Dec 17, 2012 at 11:14 AM, <pburke@...> wrote:
         



        --- In johnmuirtrail@yahoogroups.com, pburke@... wrote: >
        > I am curious, though, if the SOL performs better at higher flame
        levels, since the Helios clearly gets by on less fuel at the lower
        level. Maybe this weekend...
        >

        here are the results - I did three levels of flame.

        setup for each run:

        JetBoil Sol Aluminum pot, about a year old, used for a total of about 8
        gallons of hot water since purchased. Each test performed with 0.5
        liters of tap water (about 60F), almost new canister of Gigapower 110g
        fuel, indoors at room temperature. I cooled down the pot between each
        run, made sure the canister remained warm for even pressure. cozy on
        cup, lid closed. Time take once rolling boil was established.

        First run - setting at max - turned the flame up until I didn't see any
        change in size or noise

        boil time 1:49 mins

        fuel used 5.5 grams

        Second run - setting "medium" - nice large stable flame, but well below
        max setting

        boil time 2:12 mins

        fuel used 4.3 grams

        Third run - minimum setting - flame as small as it could be set without
        flickering and looking like it would cut out

        boil time 4:38 mins

        fuel used 4.4 grams

        Bottom line - somewhere in the middle is where you want the flame to be
        to save fuel. Going super low doesn't save fuel, just taks longer and
        risks the flame being blown out by wind if outdoors. However, the myth
        that the Jetboil is most efficient at max flame clearly doesn't apply to
        my stove.

        Maybe I should repeat the test with ice water and in cold outdoor
        conditions, but I doubt the result will be much different. I think the
        small flame doesn't work very well because it doesn't reach the heat
        exchanger fins on the cup, while once you reach those, you're good. Any
        more flame may just leak heat beyond the fins, which is then seen as
        wasted fuel. The full blast run used 27.9% more fuel than the medium
        setting. Over 8 days, boiling 2 liters of water each day, this
        difference still not really important, since at max flame you'd need 176
        grams of fuel, while at the efficient setting you're using 138 grams. In
        both cases, one 220gram canister will get you there, while a single 110g
        is too small. If you boil more water or pack for longer trips without
        resupply, it can save you an extra canister.


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