Inspired by Jim's stove reviews and after seeing many discussions on the use of Isobutane fuel cannisters commonly found on stoves such as the MSR Pocket Rocket and while we have a bit of now unseasonably colder weather, I decided to do some testing to show forum members here how these stoves perform at the freezing level.

Testing conditions
At the time of the testing, the temperature was hovering at 1C (34F), 87% humidity with a light snow fall and a 2 mile wind from the south.

Testing equipment and methods
- The 16 oz SS cup used in all the tests was run under cold water for 1 minute during each cyle of testing and to be sure that the water temperature was somewhat consistent, the water was run first for 1 minute before the cup was run under the water.

- The water for the testing is from bottled water in the fridge which the thermometer was reading at 33F.
- Between each test, the stove was allowed to cool to the point that touching the arms for a few seconds did not burn the fingers.

Two fuel cannisters were used in the test. Both were previously unused and completely full and each cannister was tested two times.

Fuel cannister #1 has been kept inside at a temperature of 18C (65F) and was taken into the house during the tests in order to try and maintain a stable and more consistent test temperature.

Fuel cannister #2 has been sitting outside on concrete and under a small roof for a few weeks. The cannister was not taken inside the house during any of the tests and again, the temperature during the test is 1C.

First Test:

Getting started.



The first test involved the cannister not being covered, set on concrete and exposed to the slight wind and falling snow.

Cannister #1 first boil water test
Water boiled in 3 minutes 32 seconds. Considering the ambient temperatures, this is fairly decent and within very acceptable times.

Cannister #2 first boil water test:

Water boiled in 4 minutes 27 seconds. After the test, there was a slight frosting of the fuel cannister which I rubbed off with a cloth before the second test below. Again this is a decent time and based on previous experience with this stove and similar weather conditions, it was very close to my estimate.

First boil test photo.



Second Test:

The second test involved the cannister being covered with a small piece of fleece that I carry for the stove when hiking in very similar weather conditions as today. The fleece is just big enough to cover and tuck into the concave bottom of the fuel cannister. Again the stove was tested on concrete and exposed to the slight wind and falling snow.

Cannister #2 awaiting it's second test.




Second test
Cannister #1 second boil water test (cannister covered with fleece)
Water boiled in 3 minutes 18 seconds. Note that this is 14 seconds faster then the first uncovered cannister test at 3:32.

Second test
Cannister #2 second boil water test (cannister covered with fleece)
Water boiled in 4 minutes 14 seconds. Note that this 13 seconds faster then the first uncovered cannister test at 4:27. After the test, there was no notable buildup of frost on the outside of the fuel cannister as compared to the previous test. Although the water boiled faster in this test, it appeared to me that based on the sound and size of the flame that the stove did not have have same high output as the first test.

Second test photo


In summary, the Isobutane stoves can and does work reasonably well at temperatures around the freezing point whether the fuel cannister is covered or not. However keep in mind that as you use the fuel, the pressure will drop and you will see substantial time increases for boiling water and more frost/ice buildup on the cannister.

As the temperature drops further and as Hikin_Jim and DougR have already noted and also based on my own personal experience of using the stove down to the -9 -10C (14F) temperature level, these stoves need a lot more attention to keep working. Again based on my experience, the cannister needs to be kept warm (in an inside coat pocket etc) before using, then covered while the stove is in use, otherwise you will be having some difficulties getting a decent flame and heating your water.

Anything much more below this and if you are relying on your stove to keep you alive, then you need to have a liquid fueled stove.

do a test with a windscreen,pulled in close and set up in a normal manner and see what times you get.i know my Gaz stove will run much better with a screen in temps that run in the mid 50's and damp.

Why do you put the fleece on? If the canister is as warm/cold as the environment, covering will just cool the canister down even more. Canisters get colder in use, now you are insulating it against the 'warmer' outside.

Pretty cool tests!

One thing that struck me was that even though the tests were conducted in temperatures above freezing (just barely, but above), the cold was affecting the tests. The warm canister beat the cold canister by about a minute, and this using an isobutane/propane mix. Isobutane vaporizes at 11F (-12C) and propane at -44F (-42C). The air temperature was some twenty degrees Fahrenheit (about 10 Celsius degrees) higher than the closest vaporization point, but the tests were affected.

I think you may see where I get my recommendation of 20F as about as low as you want to go with an isobutane/propane mix (except in liquid feed mode) even though isobutane will continue to vaporize for another nine degrees Fahrenheit below my recommendation.

It would be interesting to see your tests repeated with nearly empty canisters -- after the majority of the propane is gone and most of the mix will be isobutane only.

HJ

True. If the canister is colder than the surrounding environment, you don't want to cover it. If the canister is warmer than the surrounding environment, then you do want to cover it.

HJ

Pretty much true with "normal" gas stoves (where the fuel is fed in as a vapor). If you have a stove where the gas canister can be inverted (you need a pre-heat loop for this to work), then a gas stove working in liquid feed mode can be used down to at least 0F/-18C.

Sometimes there's a tendency to see the stove world as either gas or liquid fuel. There is a sort of "middle ground" where you have gas stoves operating in liquid feed mode that shouldn't be overlooked. In inclement weather, it's awfully nice to be able to cook safely in a tent or vehicle. I'd generally prefer to cook indoors with gas than liquid fuel just because of priming. I've primed hundreds of stoves and rarely have a dangerous flare up anymore, but still...

HJ

it's also about knowing your environment.i've been looking over some stoves for a canoe ditch kit and a tiny Gaz burner with a pizo lighter and one of the smallest Optimus Gaz carts looks like the best bet.i know the temps i'll be facing will be well above freezing,it's a spring to fall canoe season.i know once the burner is lit i can fire up something close at hand like a small stick or bit of birch bark and use that to heat the Gaz cart and get a bigger flame which will carry heat to the cart to keep the process going.if i was looking at being someplace where the temp could drop below freezing after normal day temps,like the mountains,i would want a white gas or kerosene stove of some sort.it's like a knife,in a jungle i would want a machete while in canoe country a simple Mora would be just fine.i have posted a photo here of a Gaz stove i was warming up with spoons of warm,but not hot water.once the cart warmed up a bit the burner took off and kept the cart warm enough to bring the water to a boil and keep it there while i heated a can of stew in the now hot water.

Thanks Jim. Any further testing is going to have to wait as a urgent family matter has come about overnight and we are getting ready to leave in about 2 hours. By time we get back, probably sometime next week, our cold spell here will be over...

Something similar, I have a stove that use those slim butane canisters, and even in ambient temperature in the high 20's, after some use the canister would get cool enough to unable to supply a strong flame,

I don't think the "big picture" can be emphasized enough, things like weather, terrain, elevation, etc. A stove that makes perfect sense in one set of circumstances can be completely useless -- or worse, hazardous -- in another.

Spoonfuls of hot water. I love it.

HJ