Flames coming up pot sides and effect on efficency

[Starchild]

It seems like the ideal case is to get the flame on the bottom of the pot only, not coming up the sides. This has made people look to get wide bottom pots. However I've heard one voice saying that he tested this and found no appreciable difference in efficiency so he stays with a narrow pot which is the lightest option that he has.

It makes sense that if the flame comes up over the side there may be a loss of efficiency, especially if the flames come over the liquid line in the pot, but really I took that at face value and didn't question it. So was wondering if anyone had any data points on this from actual testing. I may do some and report back.

[colorado_rob]

I carefully tested two stoves some years ago, the Jetboil (original aluminum) vs. the MSR pocket rocket with a 0.9L Ti pot. The pocket rocket definitely had some flames wasted coming out the sides, and I tested this stove at a couple different power levels, trying to minimize the side flames. It was slightly more efficient at lower power levels, meaning that the side flames did indeed waste some energy, which is obvious to me, at least. I cannot remember the number of boils at high vs. low, but in both cases, I used up an entire 4oz canister boiling cold water. I did this out on my deck in 50-60 degree weather. So yeah, it makes a small difference, at least, to minimize flames out the side.

The Jetboil was approximately 30% more efficient than the pocket rocket, and this makes complete sense in that there are no side-flames wasted, the Jetboil fins capture this energy. If I remember right, I got 20 2-cup boils out of the Jetboil, 15 out of the pocket-rocket at a lower power level. The PR at this lower power level also took much longer for its boils, for obvious reasons.

The trouble with a wider pot is that you have more metal surface area losing heat to the air, and of course the trouble with a narrow pot is you have more flame-leakage on the bottom. A wide pot with a cozy is the best option, and in fact this is what I carry in the winter for use with my liquid fuel stove (good old MSR Wisperlite).

Bottom line is that the Jetboil solves both problems, and now that they have the Sol Ti, the weight is much reduced from the original Jetboil (8.9 vs. 14+ ounces), and it is basically a no-brainer, assuming all you want to do is heat water. Those that actually cook in a pot have other priorities, of course.

[Starchild]

Ran my own test (yes some extra time this AM)

3 pots and 2 stoves checked.
Pot 1 is MSR Kettle - 4.5 in diameter
Pot 2 is Toaks 550 - 3.75 in diameter
Pot 3 is Snow Peak 450 (with the MSR kettle lid)

Stove 1 = Starlight (center flame)
Stove 2 = Vargo Decagon (side flame bloom)

Water was 350 g, tap tempature start, full boil stop, indoors, no wind effects, no windscreen

Starlight was totally consistant at about 6 minutes boil all 3 pots and 10 g fuel. For the Snowpeak the was some flame spillover and the handle was very hot at the boil.

The Vargo was consistant with the MSR and Toaks pot with 4m30 seconds boil, 12 g,11g fuel (respectivally), but for the Snowpeak which had almost the entire flame up the sides it went up to 14 g fuel and boil time went up to 5m30s.

Conclusion:
It appears only to make a difference if the flames hit the bottom or not, spillover does not seem to factor in. I would suspect a difference if the spillover flame exceeded the liquid level inside but did not test that.

[Starchild]

EDIT/ addition the Snowpeak 450 was 3in diameter, the smallest of the 3

[Connie]

I like having the flames come up the side of the pot.

I have a Vargo Sierra 750. It has sloping sides.

It is 2-inches deep, 6-inches diameter at the top, and, 4-inches diameter at the bottom.

The flames come up the sides. The food has an even heat source.

Add to that, the folding handle locks in place. I like it.

I have other cookware: GSI Hallulite Minimalist and teapot, I use for Rest Stops on the highway, or, for car camping at the parks.

I have not made comparisons, except to notice I no longer have burnt food.

I also have a JetBoil Zip for hot boiled water, right now. I make hard boiled eggs and use the water for cocoa, while traveling to the coast. In my experience, JetBoil is not useful for a heavy stew, but it will do a non-creamy soup.

My Summary: In my experience, a concentrated flame at the bottom of thin cookware is not "efficient". Only JetBoil is faster.

[billsandysprings]

Isn't the caldera cone supposed to solve this? Don't have one yet but have the same problem and was considering. http://www.traildesigns.com/stoves/caldera-cone-system

[billsandysprings]

Well now I see it's maybe not for petroleum stoves....

[peakbagger]

I rigged up a hanging side shield for my pocket rocket that hung off the burner arms and saw a big increase in real world efficiency compared to the open pot on an open burner. When simmering I could turn the flame down a lot farther and still keep simmering. It made it a lot nicer to use on an open picnic table in a breeze.

[MuddyWaters]

DependsDepends on a bunch of particulars, but generally yes. The poster child is the supercat stove, which might boil in 4 min by engulfing pot in flames, but takes .75 oz to do so. Whereas my setup does it on 0.4 oz, but takes 7.5 min.

With a canister, my gnat will boil 2 cups on 0.18 oz fuel. As good or better than than jetboil. Just have to turn it down very low, to alcohol times. Boil in 3 min and it will take twice that or more, depending on setting.

I used canister on JMT and used half of a 100 gm canister this way. Others used multiple large canisters.

Anytime you apply heat faster than the pot can absorb, you are wasting fuel. This is all the time, significant heat is always lost to surroundings. But you can definitely make it worse.

[July]

A little flame licking up the side is not that big of a deal. Unless your burner width is wider than the dang pot...

[Odd Man Out]

I use the Olicamp XTS pot with and alcohol stove. The pot has a heat exchanger to maximize efficiency and the stove is a center burning stove. When I switched to this system, I noticed that my wind screen no longer gets hot (or even warm) when the water water boils suggesting much better efficiency. I attribute this to the heat exchanger preventing heat from going up the side of the pot. The increased rate of heat transfer also allow to get high efficiency and high power at the same time. Now I boil 2 cups of water in 4 min with just under 0.5 oz fuel which are much below "alcohol times". Also, this pot has a ~1/1 height to diameter ratio which minimizes surface area and thus maximizes heat retention. Since then heat exchanger distributes heat around the perimeter of the base, I don't have problems with food scorching due to a hot spot in middle.

[The Cleaner]

The Svea 123 in afterburner mode solves this problem....

[soulrebel]

Recently picked up a toaks ti alky stove top jetted, it seems to work really well with the chickenwire stand. I saw that zelph had a top jetted as well...minibulldesign bios micro stove was the smallest bloom i could find and i used that for the last couple of years...

[July]

Recently picked up a toaks ti alky stove top jetted, it seems to work really well with the chickenwire stand. I saw that zelph had a top jetted as well...minibulldesign bios micro stove was the smallest bloom i could find and i used that for the last couple of years...

Sounds like a Thesis' in Work. Don't Stop

[MuddyWaters]

A little flame licking up the side is not that big of a deal. Unless your burner width is wider than the dang pot...

Most of time it does not matter.

But sometimes, when you have to go long distances between resupply, it can.

Some people also enjoy carrying minimal precise amounts of consumables. They derive fun from accurate planning and execution.

Stupid? Could be. But then again maybe so is the guy with the heavy pack.

HYOH.

[Connie]

If efficiency is the least amount of fuel, and, getting the hot water only, then, what stove and what cookware will do that best?

Is that the efficiency you are after?

[Starchild]

If efficiency is the least amount of fuel, and, getting the hot water only, then, what stove and what cookware will do that best?

Is that the efficiency you are after?

Was more looking at the more specific case of how does flame spillover the sides effect efficiency, and if spillover should be avoided if practical to increase efficiency.

As pointed out in my experiment above spillover does not seem to matter at all as long as the flame touches the pot bottom directly first before spilling over.

However spillover has the issue that the pot handles could get to hot to touch directly.

[Just Bill]

As far as I know- Zelph has been the only one to point out spillover as a non-issue. Obviously a good source and knowledgeable fella, but only one source.
As you also mention- spillover has other problems like pot handles or lids overheating. I think Zelph was also referring to the more mild flames of an Alchy stove, rather than the racing high octane spillover of a gas stove (I could easily be incorrect though).

Odd Man Out's 1:1 diameter to height ratio makes lots of sense for lots of reasons. Until he said it, I hadn't thought about it much, but you are using the least amount of metal for the largest volume of water held as well as getting the reduced surface area he mentioned.
The old rule of thumb was short and fat is better than narrow/tall- I think OMO's rule is a better one.

My opinion has always been, size the stove to the pot regardless and avoid spill over. Many stoves are made with group, winter, and larger pot needs than many long distance solo hikers. So the big burner heads for 1 quart plus pots don't make much sense. I've never been a fan of the MSR stoves for that reason, although the newest pocket rocket seems to have a fairly small burner.

Two excellent small burner head stoves.
The Olicamp/Firemaple stove has the most compact burner head. The top burner vortex is very efficient and tight. It's basically a water boiler though.
My longtime favorite prior to that was the SnowPeak Giga stove (not the TI which has a different burner head) The giga has an acorn shaped side burner.
http://www.rei.com/product/643058/snow-peak-gigapower-stove-with-piezo
This is a much better "all around" stove and easy to cook on.

After matching burner to pot- as many mentioned- simply "taking your foot off the pedal" results in big increases in efficiency. Waiting an extra minute is probably worth getting an extra few boils per canister.

Clearly the heat fin technology in Jetboil, Olicamp and others is very useful.

If I were to experiment with anything- it would be to answer the question-
Is the Olicamp AL pot actually lighter than a comparible TI pot when you factor in fuel efficiency?

[Odd Man Out]

If I were to experiment with anything- it would be to answer the question-
Is the Olicamp AL pot actually lighter than a comparible TI pot when you factor in fuel efficiency?

I can't answer that. The pot isn't exactly UL, but you could shave an oz or two if you fabricate lighter handles and lid. Both can easily be swapped out for lighter options, if you want to.

I also like the 1/1 dimension for eating out of. Not too deep, not too shallow.