Nov 19, 2013 at 9:47 pm #1310030Nov 20, 2013 at 7:22 am #2046450
It apears that the data may be skewed somewhat. You didn't take into account the number of BTU's produced from a given amount of fuel, nor, the the maximum efficiency at any given temperature. For example, the Reactor seems like it is the most efficient. But, it may simply be burning fuel at a lower rate, and NOT producing as much heat output, hence wasted heat, when you measure the actual BTU output. I would guess around 6000BTU based on what I am seeing. Only the heat exchanger and close fitting pot make it efficient enough to use that small of a stove in cold weather. Typically, a winter stove pumps out 8000-10,000 BTU, some more.
But, measuring a stoves true output can be difficult. Some don't even function in any meanfull way at 0F. Caffin's stove works well with a cone or tight fitting wind screen. The same may not be possible for the Reactor or any upright canister stove. As you say, a lot of questions.
Many still consider melting snow at 0F to be a challange. I never go out when it is that cold,so I cannot say. The physics say that the ice will require more heat to melt betwwen 0F and 32F(water) than 32F(snow) to 32F(water.) Convectional heat loss (wind,) radiative heat losses, and insulating value of the sides and lid, the material the pot is made of (and any coatings,) the actual color of the pot, heat exchanger, etc, all make a measurable difference in fuel consumption when you are making water for groups. Things like this are much easier to measure in large quantities.
A good start Ryan! Looking forward to the rest of the parts to the article whether or not you ever measure the BTU outputs. Thanks!Nov 20, 2013 at 12:51 pm #2046577
@danepackerLocale: Mojave Desert
I'll stay with my MSR Dragonfly when temps are near or below zero F. I KNOW it will work and even save fuel with its great simmering ability.
Coupled with my 1.5 L. Jet Boil pot (W/ heat exchanger fins on the bottom) and a Backpacker's Pantry oven covering the pot my winter liquid fuel setup is quite efficient.
My "other" winter stove is a Trail Designs Sidewinder with the woodburning Inferno insert that makes it a highly efficient gassifier stove. Even with fast burning evergreen wood it is a reliable stove.Nov 20, 2013 at 12:56 pm #2046578
@glettsLocale: Northern California
Hey Ryan – wondering how you're measuring the GSI 5 L pan…typically capacities are measured to the rim. The GSI Base Camper Large 5 L pan is 5 L to the rim. Obviously that's not the useable capacity, just as you can't use the whole liter on a Jet Boil Flash or the .85 L with an MSR Titan Kettle.Nov 20, 2013 at 4:38 pm #2046651
Interesting article. I'm slated to spend 4 days in the Adirondack High Peaks the last week of December with 3 or 4 other people. As a result, this series of articles feels particularly relevant to me.
Will you be adding any heat exchanger pots to the mix? I own one of Roger Caffin's new LW invertible remote canister stoves, as well as a Whisperlite. I'm torn on which to take, and I still don't know what pot would be most appropriate.
I have a 2L stainless Steel pot, and I have an MSR clamp-on heat exchanger. It's a very heavy winter system. I would be very interested in whether something like the Primus Etapower HX pot, or something similar but larger, would perform.Nov 21, 2013 at 7:03 am #2046827
I'm new to winter and cold weather mountaineering. Wondering how elevation would affect stove performance in addition to the cold temps you plan on testing. Love this article – thanks for posting!Nov 21, 2013 at 12:58 pm #2046943
I've used a white gas stove up to nearly 20,000 feet, and I never noticed much of an serious effect of elevation on fuel usage. Obviously it gets colder up there, so you tend to need more snow melting and cooking going on. Also, snow tends to be colder and drier up there, so the entire snow melting process tends to be a little less efficient than at sea level.
–B.G.–Nov 22, 2013 at 8:35 pm #2047326
@jamesdmarco, who wrote: "You didn't take into account the number of BTU's produced from a given amount of fuel, nor, the the maximum efficiency at any given temperature."
I know. Of all the times that I've freezing my butt off trying to get dinner done so I can go to bed, I'm not sure if I have ever, ever, EVER thought about BTU's or E = f (T). ;)
Seriously, though, I'm only interested in trying to collect data that will allow some extrapolation into field scenarios, and then try to validate it as best as possible with some actual field scenarios.
@Danepacker – sounds like you have a good setup here. Do you have a feel for how much fuel your setup consumes per "pot" of water at cold temps?
@gletts – I'm measuring nominal capacity at a volume of 3/4 to 1 inch below the pot rim. This allows for a vigorous boil without a rowdy spillover.
@jjmcwill – I hadn't considered heat exchanger pots yet (other than the MSR Reactor 2.5L being tested in this series) but I certainly would, if it's consistent with the theme (large water volumes). Do you have a recommendation?
@leverett – I won't look at elevation per se in this series because previous tests that I've done don't show a lot of differences at the elevations we have in the US. For example, on any given winter trek I might travel between 7k and 12k, which isn't a lot of change. Note that water boils at a lower temp at higher elevation, so in theory less fuel is required to reach boiling. I've looked at the math, and it doesn't justify much investment of time to consider fuel needs until you get to altitudes frequented by high altitude mountaineers.
I will definitely will look at temperature range – from about 40 deg F down to minus 20 deg F or so. These stoves are more sensitive to temperature differences that we're likely to see in the winter than they are to elevation differences.Nov 23, 2013 at 7:09 am #2047388
I am personally looking at the Primus Eta heat exchanger pots for my trip. They are the only ones I can find that are offered in larger sizes. They sell 1.0L, 1.8L, and 3.0L sizes.
It would be interesting to know if the cost and weight penalty make HX pots worthwhile over standard aluminum models.Nov 23, 2013 at 11:06 am #2047437
OK, I'll add this pot to some tests, and if the results look promising, we'll investigate further. Do you know if the heat exchanger can be easily removed from the bottom? It would be neat to have one version with and one version without for side by side comparison.Nov 23, 2013 at 11:52 am #2047445
I do not think the heat exchanger is removable. I don't have one yet, so I could be mistaken.
I look forward to the test results! :-DNov 23, 2013 at 3:40 pm #2047502
@anthonyjhuhnLocale: Mid West
Would Ruta Locura make you a carbon fiber lid for that popcorn kettle? ;)Nov 23, 2013 at 10:22 pm #2047573
Some time back I ran some tests of my own that are related to this. I took my 4 qt Open Country pot, filled it with 12 cups of water at 50 degrees starting temp, and at 40 degree air temp, in a garage with the door open but effectively no wind. so very similar there. However, the stoves were White gas stoves. – Whisperlite and Simmerlite. Results: each stove brought the 12 cups to a boil using 43 grams fuel.
The really interesting thing to note is that this number is precisely half of my average fuel usage for solo snowcamping trips where I have to melt snow, and I typically produce about 2 liters twice a day, each time lighting the stove once and running it continuously until I have the water I need and the water for my meal is boiled. So this is an excellent simulation of my actual usage.
Another data point: Analysis of my fuel usage from snowcamping trips where I have tracked both fuel usage and the number of days I found running water yields the info that a melting day consumes 1.5 times the fuel of a non-melting day. Note that these are spring ski trips, where during the day I am able to add snow to my water bottle and it will melt, so that I can start the day with 3/4 of a liter of water in my bottle and drink all day by just adding snow to the bottle every time I drink. So I only need to melt the morning and evening water. For deep winter trips more melting would be required.
Given the numbers you've come up with, it looks like only the Reactor (so far at least, we'll see what the Caffin stove can do) can beat the Simmerlite for weight efficiency for a week-long trip. Fuel usage by weight is the same, and fuel container weight is lower for white gas since I can carry it in plastic bottles. Using a half-liter Sigg bottle for the tank and refilling from plastic, I can carry 21 ounces by weight in 6.3 ounces of container, and as the trip gets longer the average container weight goes down since it's all in plastic after the first 12 ounces by weight.Nov 23, 2013 at 11:00 pm #2047575
Paul, why not just carry the fuel and use it out of the same 1L Sigg bottle?
On ski tours, I never plan my fuel on being able to find running water.
–B.G.–Nov 24, 2013 at 4:31 am #2047584
I'm just doing a personal assumption check.
I recall energy density of various fuels being discussed somewhere in the forums in the past but can't find it, and I couldn't remember how canister fuel compared to White Gas.
Maybe most of those discussions were related to alcohol vs canister fuel.
I DID find a table of fuel energy densities on the Optimus website
Does this seem fairly accurate? Is the entry for LP gas good enough when discussing the 80/20 Isobutane/Propane canister and comparing it to white gas?
If there had been a significant difference in the energy density between white gas and alcohol, one might have argued that, despite the weight penalty of a white gas stove, it would have been more weight efficient once you reach a particular quantity of group water to be boiled or snow to be melted. However, the chart referenced above would indicate this would never be true, because canister fuel and white gas should both provide similar energy per weight.
If so, the only other advantages of white gas, as I'm sure have been discussed often in the past, are fuel cost and packaging.Nov 24, 2013 at 6:13 am #2047589
Jeff, Yes, pretty much.
WG and canister fuel have about the same energy density.
Alcohol has far less.
I usually use a balance of around 20,500 BTU/lb when checking this. WG has around 19,500 per pound (note that it is mostly pentane, hexane, heptane.) Similar.
Alcohol has about 11,000 average (blend of ethanol, methanol.) On long trips in winter, it makes no sense to use alcohol, especialy for group cooking. There just ain't enough heat in the fuel.
However, you cannot have canister gas without a canister. These weigh about 30-40% of the fuel weight, much reducing the fuel overall density. The same applies to WG, of course, but you can carry WG in a 1 ounce container(6,8,10,12,16, 20 or 24oz, or 1 liter & 2 liter) soda bottle for anything up to 69-70 fluid ounces. Note that canisters are already in mass weights. WG is not and WG is in FLUID ounces. Mass/density is close to .78 that of water so to carry 12floz of WG fuel, we multiply by .78 to get 9.36oz of weight. With a 1oz fuel bottle we get around 10.36oz in weight. This is for roughly 11407 BTU's in fuel.
12oz soda bottle: 1oz
12 floz of WG: 9.36oz
Fuel efficiency: 11407BTU/10.5oz or 1086BTU/oz
For canisters we get a total weight of around 220g + can = 308g or about 11oz for roughly 10067 BTU's in fuel.
Can: 88g (3.14oz)
Fuel: 220g (7.86oz)
Fuel efficiency: 10071BTU/11oz or 916BTU/oz
Clearly, based on fuel, the WG is superior to take. However, for shorter trips, smaller groups (ie, less fuel used,) you consider the weight of the stove. WG stoves, are heavier, on average, than canister stoves. Usually offsetting the weight of the fuel. So, this is why canisters are so popular, even though they are less efficient, fuel wise. In the above, Ryan was trying to decide on the best performing stove for winter group use, but this can vary based on all the criteria he mentions, eg pot size, wind, etc and the base BTU efficiency of each stove.Nov 24, 2013 at 7:05 am #2047594
Is it safe to carry white gas in soda bottles? I'd never tried that before.
On our mountaineering expedition, we carried spare fuel in metal MSR fuel bottles. We even had two or three big ones: 40oz or 1.5L or something like that. If they were anything like the Primus 1.5L fuel bottles, the bottle alone had to weigh 9.6oz or more.Nov 24, 2013 at 8:18 am #2047607
Bob – using the smallest sigh bottle I have and then carrying the rest of the fuel in plastic is lighter – my larger bottle weighs more than the small one plus the plastic.
On expecting running water – I don't always, but depending on snowpack and how late in the spring I'm going, I may. If it's mid-May or later, I've found I usually find water even in a big snow year; if it's closer to mid-April it has to be thin snowpack. I keep track of how many days I have to melt, to help with planning future trips. Campsite choices play a big part as well. If I'm going to be up on the ridges then there's much less chance.Nov 24, 2013 at 8:24 am #2047608
Jeff – I've carried WG in plastic safely on several trips up to 9 days. I do look for more robust bottles. Those really thin wall water bottles seem to flimsy to me. Before I tried it on a trip, I tested by storing gas in a plastic bottle for several months with no effect on the bottle or cap.Nov 24, 2013 at 9:54 am #2047627
I would guess that the heat exchanger becomes less important as the pot diameter increases, but that's just a guess.
Heat exchangers on the bottom of the pot probably won't be removable, since there needs to be a good thermal connection to the pot, and I think that a clamping system would be far heavier than welds.
The MSR around-the-pot removable exchanger is 170 grams, and I don't know whether it will fit any of your pots. It obviates that tricky aluminium-titanium weld that's problematic on the Jetboil Al/Ti pots (you don't want a titanium heat exchanger because Ti is such a poor thermal conductor, and the two don't love being welded together).
Jetboil has 2 options that may be of some interest:
3.0 liter heat-exchanger pot: 550 grams, probably usable on non-Jetboil stoves.
1.8 liter sumo heat-exchanger pot: 225 grams for Ti (or 325g for Al). Aspect ratio is probably too high to be useful on non-Jetboil stoves or to be easy to shovel snow into, but you could carry 2 1.8-liter pots at less weight than their 3-liter pot, which may or may not be more versatile. No reason other stoves couldn't clamp Jetboil pots, but AFAIK they don't…Nov 27, 2013 at 5:32 am #2048537
Jeff, Yes. There is always saftey concerns with carrying any type of fuel canister.
Some things to consider:
Resistance to the materials being contained
Temperture(min & max)
Expansion and contraction of the fuel, air, water and container materials
PET bottles (a standard clear plastic soda, or water bottle) covers all these things fine. However, the caps for soda bottles have a seal that breaks down over time. After two years of use, I needed to change the caps I use because of this. Some car gas, with the additives and any impurities in the refinement process' can also attack the cap seals rapidly, thou much slower on bottles. It is fine for a month though.
The actual fuel cans are usually plastic. No difference.
However, there IS a concern with mixing these bottles up with your drinking water. Or, having someone else with you that will grab the wrong bottle for cooking, etc. I used to make a fuel "bladder" by heating the pet bottles carefully over a flame while filling them about 1/10 full with some fizzy soda. This actually forces the dumples out and removes the "flat" bottom. Sort'of the reverse of the blow moulding to create the bottle. This shape is not one anyone is familiar with or would mistake in the dark. Still, a light sanding with 1000grig sandpaper and marking with a permanent marking pen "XXX FUEL" around the bottle makes these a bit safer. Solo? I never bother with this and just use a different bottle. A coke or pepsi bottle for fuel. Gatoraid for water.
I tried the very thin water water bottles. But after 3 trips, I had one develope a small leak on one of the small bottom dimples. I just carried the bottle upside down after noticing a smell. Might be a bad bottle, but they might be too thin. I never tried it again.
The weight of WG stoves is not a lot different from a lot of others. The Simmerlite (now opsolete, but some are still available) was about 9oz and makes an excelent winter stove. You cannot cook or simmer on it, though. My SVEA 123r weighs about 17oz for the stove and wind screen, but is too small for two in winter. The weight of my old XGK is about 17oz (plus the fuel bottle for pressurizing 2.5oz.) The Reactor weighs about 11-12oz. The Windpro weighs about 7oz. A few ounces, compared with 30 pounds of pack weight for Winter, doesn't make much difference. Gone are summer's SUL trips. Even UL and Winter in the same sentence is sort of joke. Winter shoes and socks weigh more than the stove. Hey, ha…unless you do like Roger C's avatar.
I have heard on this forum that it is possible to rig a pump on PET bottles, but, I never tried it. They do contain several bars of pressure, though. Probably enough to feed a Simmerlite or the like. Some sort of thread adapter was undobtedly used. Perhaps a Gatoraid bottle for the larger mouth? Anyway, getting way off topic. My apologies.Dec 5, 2013 at 10:27 am #2051114
I've been waiting for a couple of months to do some patio tests of a canister cozy concept that I've come up with. So we finally are 'enjoying' our first sub-zero *F temperatures of the season here in Boulder. Time to do some testing. I'm posting about it in this thread, because it seems to be somewhat relevant to the theme.
But first, I'd like to report on something that I learned last week, before this cold wave hit. I am using a Snow Peak Giga stove with an integrated wind screen and reflector. A detailed description of this setup can be seen in this 2 year-old thread:
The aim of this test was to compare the boil times and fuel consumption of 2 cups of 50* tap water with different levels of flame intensity in high wind conditions. It was a very windy day (gusts of up to 45 mph), with ambient temperatures of 50* F. I did 2 tests at each level of flame intensity, and averaged the results, which were as follows:
Flame intensity, Boil time, Oz. of fuel consumed
Very low, 6:00 minutes, .25 ounce
Medium, 4:45, .25
Medium-high, 4:00, .20
High, 3:40, .20
What is curious to me is that this stove was actually a little bit more fuel-efficient when I opened the valve more fully, which goes against conventional wisdom. The bonus is that the water also boils faster.
OK, enough of this. Let's get to the cold weather tests. I came up with an idea that I thought might help when using a canister stove in very cold conditions. I made a canister cozy from Reflectix and duct tape. In the following photo you can see the components. I cut the compass off an REI zipper pull to give me a cheap thermometer, which I secured to the bottom of a fuel canister with duct tape. This is there to allow me to monitor the approximate temperature of the canister, to be sure that it doesn't overheat. There is also a 1/8" piece of Lawson's Evo pad, and a slightly larger diameter piece of titanium foil. These act as a stable non-conductive base for the canister. What is not included in the photo is a single chemical toe warmer, which is the key to this whole setup.
The next photo shows the canister inserted into the cozy, and sitting on the insulating base:
This final photo shows the stove and windscreen attached to the canister, ready for testing.
Yesterday morning the air was +10* F, it was lightly snowing, and there was no wind at all. I had placed everything on the patio table the night before, to let things get as cold as possible. I took the cold pot inside and put 2 cups of 50* F tap water in it and stepped outside to see if I could fire up the stove. For this first test I did not use a toe warmer, so everything was +10* F. I was somewhat surprised that the stove actually lit, after holding a Bic to it for about 5 seconds. There must have still been a little propane in the mix (Snow Peak canister fuel = 15-20% propane, 80-85% isobutane?). I had to open the valve fully to maintain a flame. The boil took 7:30 minutes, and it consumed .20 oz. of fuel.
For the second test, I placed a toe warmer under the canister, and fairly well sealed the bottom of the cozy against the Evo pad underneath.I didn't want to completely seal it, as the toe warmer needs a bit of air to feed its chemical reaction. I let the warmer do its stuff for 15 minutes before I fired up the stove. Just before I lit the stove, the little thermometer showed 45* F–it warmed things up nicely. By this time the morning sun was shining on the black duct tape of the cozy, so that might have helped to warm things up. The air was still only +10* F though. This time the stove fired right up. I only had the valve open about half way, which is all I needed for a robust and steady flame. The water boiled in 5:00 minutes, and again, used just .20 oz. of fuel. After the boil, the canister thermometer read 35* F. I assume that the canister had cooled itself slightly. The cozy and toe warmer combination seemed to do what I'd hoped.
Alrighty then, now comes the Phase II trial. At 5:30 AM this morning, the ambient temperature on the patio table was a bracing -9* F! Not a hint of a breeze, not snowing, just friggin' cold. All the stuff was left out on the table overnight, as before. Now I could find out what the real deal was. I put on my WM Flight pants, my warmest parka, my beloved BR beanie, and the BR down mittens Doug sold me, grabbed a mug of joe, and went to it.
The stove wouldn't even give a hint of lighting without the toe warmer setup. So I placed one, and went back into the house for 15 minutes. The toe warmer raised the canister temperature to +10* F, and the stove did light after a few seconds with the Bic. I had to turn the valve completely open to keep things lit. The flame was pretty weak, but it kept burning, slowly. I finally got a boil at the 23:00 minute mark. The boil consumed .25 oz. of fuel.
I think I learned what I wanted to know. The toe warmer concept does does seem to sort of work, at least until the temperatures go really low (its performance decreases as the temperatures drop). My results with the toe warmer setup at +10* F were about the same as the windy 50* F day test I first reported on, but at -9* F it sucked. Maybe a hand warmer with its higher heat output would work better. But I'm thinking that only something like an inverted canister or a copper wire feedback thingy will achieve decent results at 0* F or below. White gas, anyone?
These results confirm for me Ryan's observation that one uses about the same amount of fuel for a boil at any temperature. I also feel certain that very cold conditions will sap heat from the system, prolonging the time to boil. I'd love to have one of you physics types to tell us about partial pressures and how fast each type of gas gets used up. Would a canister composed of 25% propane-75% butane (eg, Optimus brand) function well at zero degrees until the propane is depleted? Actually, I might have learned something about this. Read on, I haven't told you everything yet.
I also tested my new 1.0 liter Reactor under the same conditions (I first tested the Snow Peak/cozy, and while it was cooling down I did the Reactor). For the Reactor, I used a new Optimus 25%-75% canister, no cozy, no insulating base, and no toe warmer. The results:
On the +10* F morning, The reactor fire up right away, it took 5:30 minute to boil, and it consumed .25 oz. of fuel. A slowish boil, twice as long as usual, but still OK.
But this morning, at -9* F, it was a far different story. It took 20 seconds with the Bic, and then it barely heated up. Never a bright orange glow, but just a bluish dancing flame. I placed the pot to capture what heat I could, and then after 4 minutes the blue flame went out. The higher propane content didn't do much at all, so I'm thinking that the Optimus blend is a dud for cold conditions. Maybe next time I'll try the MSR blend–it's likely the best-of-breed.
Thanks for indulging me, folks. Now I'll read what I've posted and correct my spelling errors before BG whaps me.Dec 5, 2013 at 12:14 pm #2051152
No whapping, Gary.
I was just staring at the first two photos. I tried to figure out how you get that butane canister to work… the one marked Empty.
–B.G.–Dec 5, 2013 at 1:23 pm #2051173
That's a diversionary tactic, Bob, so that the little kids next door don't burn my house down when I'm not looking (they can't read). Blank canisters are also good for attaching a stove when I want to stare at a stove setup from across the lving room, like when the ball game is getting stupid, or when the news anchor is reporting something that doesn't interest me.
Thanks for not whapping. I must have gotten my spelling corrected just before you checked out the thread post. Hey, you hiking this week? You are getting a weenie version of this storm front we are enjoying. Don't forget your toe warmers.Dec 5, 2013 at 1:29 pm #2051176
@retiredjerryLocale: Oregon and Washington
Good test Gary – thank goodness for winter so it gets cold enough to do tests : )
You did two tests of each and averaged. What was the range of these two and how does that compare to the difference between low and high (.25 and .2)? This would give an idea whether that difference was due to randomness or really due to flame level.
When I was testing, it seemed like low level uses maybe 5% less fuel than high level but it could have been due to random errors.
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