Concerning the Jetboil

[mambo_tango]

I fired up my jetboil today and I was wondering: how high do you put the flame level to get your water boiling? I don't want to waste my fuel while I am on the trail. I saw someone post that they only used 5 cannisters their whole thru-trip - which I think is really good since they aren't recyclable.:-?

[mrc237]

The main feature ot the "JETBOIL" is speed I don't think simmering everything is saving fuel. I know that I got 14-16 meals out of one cannister, which was fine by me. The hiker that used only five for a thru was either very frugal with his fuel, a very fast hiker or ate alot of town meals. I'd be interested in knowing. GL on your thru!

[Almost There]

I usually don't turn mine up that high...and it still is boiling within a few minutes.

[Nightwalker]

By weighing the canister before and after boiling 16 ounces of water with a number of different valve settings, I determined that wide open, or close, is the most efficient way. This is exactly the opposite of some stoves that I've used before that had no heat sink on the bottom of the pan. The heat sink is the huge difference with the Jetboil.

[iliketacos]

Mambo, I would assume that the amount of heat that you put into a system is directly proportional to the time it takes the system to absorb the heat. Restated, the fluid used to boil your water should be the same regardless of the setting when you view the time it takes to boil it. But, this does not take into consideration elevation, extreme cold or hot temps. An example may be driving from point A to point B at different speeds, as long as the distance isn't too far I would assume that the efficiancies of fuel used are minimal. I found that the jetboil works best when its cranked wide open as nightwalker suggested, and the name of the cooking system does start with the word jet. What I need is some bag times for pasta.

[terrapin_too]

By weighing the canister before and after boiling 16 ounces of water with a number of different valve settings, I determined that wide open, or close, is the most efficient way. This is exactly the opposite of some stoves that I've used before that had no heat sink on the bottom of the pan. The heat sink is the huge difference with the Jetboil.

Do you remember any of the numbers? I'm measuring a very consistent 0.1 oz of fuel for each cup boiled. I haven't "controlled" for flame height, but in general I'm not using max flame. I'm also hoping to compare fuel efficiencies between a Jetboil PCS and a PocketRocket+Evernew 1.3 liter.

[4eyedbuzzard]

Just to throw this into the mix:

Heat transfer will be at its maximum efficiency at the beginning of heating. As the delta T between flame and container/water decreases and the water/container heats up, transfer efficiency will decline.

Heat loss from the water/container to ambient environment will be at its minimum at the beginning, but become larger as the delta T between water/container and ambient air increases.

Heat loss from the water/container probably has a much greater effect on fuel usage and efficiency than the heat tranfer efficiency as the difference(change) in delta T between water/container and ambient is much greater than the delta T of flame to container/water during the process.

In a controlled environment there is probably an optimum curve starting with lower fuel settings and increasing fuel as heating progresses. Achieving this control in the field is probably unrealistic.

Another overall efficency concern is that heating water to a full boil is a waste as the energy required to achieve phase state transition to boil is quickly lost from the system as steam before being used to cook anything.

[iliketacos]

4eyed,

I would think that the optimum curve would go the other way with a higher setting, with the Jetboil system, to add more heat to the volume of water in question which would force any potential heat loss into the system rather then losing it through evaporation or outside elements of the system. But, water acts funny as shown by its properties at just below freezing (it doesn't go to a solid state). I also have been wondering about the actual efficiancies of the fuel and the fuel canister to heat the water-which is probably the best way to approach this.

If the canister releases the same unit of fuel times X for each increase in demand I would assume that the heat transfer would be proportianal without much loss-I say "much" because I would assume there is a thermodynamics student out there that has graphed the hell out of this topic.

So, is there a more efficient setting for the Jetboil in the field? I would say yes, it's more efficient to crank it on high if you use the pot cozy, and the lid as provided-these two items slow heat loss. But, as 4eyed noted once it hits the phase transition state-the boil-turn that sucker off or else your just wasting fuel.

You could also add salt to the water, which will allow the water to boil at a higher tempurature but not boil faster-which I think is important for FBC.

One could also stir/agitate the water to add additional heat to the water.:rolleyes:



Here's the link for jetboil specs: http://www.jetboil.com/Products/Cooking-Systems/Group-(GCS (http://www.jetboil.com/Products/Cooking-Systems/Group-%28GCS))

[Earl Grey]

So it is decided then that with the Jetboil one should turn it wide open until you just get the water boiled and then shut it off? This is the most efficient way to use the least amount of fuel?

[zelph]

Just to throw this into the mix:

Heat transfer will be at its maximum efficiency at the beginning of heating. As the delta T between flame and container/water decreases and the water/container heats up, transfer efficiency will decline.

Heat loss from the water/container to ambient environment will be at its minimum at the beginning, but become larger as the delta T between water/container and ambient air increases.

Heat loss from the water/container probably has a much greater effect on fuel usage and efficiency than the heat tranfer efficiency as the difference(change) in delta T between water/container and ambient is much greater than the delta T of flame to container/water during the process.

In a controlled environment there is probably an optimum curve starting with lower fuel settings and increasing fuel as heating progresses. Achieving this control in the field is probably unrealistic.

Another overall efficency concern is that heating water to a full boil is a waste as the energy required to achieve phase state transition to boil is quickly lost from the system as steam before being used to cook anything.

Whoa!!!! I like that stuff.

Throw this in for thought, the "Supercat" does the same thing, full bore all the way. Wide open, beginning to end. My opinion is that it is the most efficient alcohol stove design to this date.(open flame that is)

I think the jetboil should go full bore until you can hear the transition start to occur(pea size bubbles on bottom). (unless you want to purify water)

[hopefulhiker]

Just watch your pot to see when the water boils. Sometimes I let my pot go too long and that wasted fuel.. For the Jet Boil I turned it almost all the way up....
"Watch pot never boils"