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.