The Xtreme Stove, courtesy Coleman
Field and test information
In the approximately two-month period discussed in this Field Report, I conducted three backpacks with the stove. In each case, it was used in sub-freezing weather. The elevations at which the stove was deployed ranged from 1200 ft, 366 m (Harriman State Park) and 3500 ft, 1066 m (Catskills). Daytime temperatures ranged from 30 F to 60 F (-1 to 16 C). Cooking was conducted at temperatures ranging from freezing down to 20 F (-7 C). I also conducted one bench test in preparation for the Long Term Report, in which the canister and stove were cold-soaked overnight outside at temperatures close to 0 F (-18 C).
Product use and Performance
November was generally mild, though night temperatures were typically below freezing. We had snow late in the month and we've received several storms since. My first trial of the stove was on a chilly night on the col between Friday and Balsam Cap Mountains in the Catskills, on about eight inches of rather early snow, while leading an Appalachian Mountain Club backpack. There was a strong wind, which gave me a good opportunity to test the built-in windshield on the stove (all of the testing so far was done without a windshield. This cups the burner and (in my experience so far) prevents most gusts from affecting the flame from the burner.
On this trip I was using a MSR one-liter (one quart) kettle, about three-quarters full, with a mix of water and snow. I didn't measure the boiling time (with so many variables in the outdoors, boil times are irrelevant), but the stove made extremely short work of the job. I was pleased to see that I could, by adjusting the valve, prevent most flame "leakage" up the sides of the pot, though on full-blast naturally this did occur. The valve indeed efficiently regulates the output of the stove, and a low simmer is possible, although the flame burns with a faint sputtering sound on low settings.
There were no problems lighting the stove and keeping it running. Others in the group, using standard canister stoves, experienced some difficulty getting their stoves to run properly, and I was able to help by providing a pan of warm water with which to warm the canisters. The Xtreme stove, because it uses a liquid feed rather than a conventional vapor feed of the kind used by most canister stoves, was unaffected by the colder temperatures.
I deliberately left both stove and canister out overnight. Towards dawn a warmer wind blew in, and the temperature was hovering around the freezing point. My stove had a fair amount of slush snow on it as a result. I shook it off, and it lit without fuss (I generally protect my stove overnight, but this was for testing purposes).
My next backpack was in Harriman State Park, north of New York City. Temperatures were a few degrees below freezing at night. As an experiment, I decided to do all my water purification on this trip by boiling, in order to test fuel consumption. I started with a new canister. I boiled my water (which was at about 50 F, 10 C) for two minutes. I boiled approximately one liter (the rest I carried in). I weighed the canister on return and I'd used about 1.4 oz (40 g). The cartridge I was using (Coleman's large size) contains 300 g of fuel. The boiling water I prepared was used in the preparation of food and hot drinks, so this fuel consumption figure is for both sterilization and cooking.
Before testing the stove at lower temperatures, I wanted to ensure that it would operate properly under such conditions, as I didn't want to be out in bitter cold weather with no hot food or the means to melt snow for water! During a cold snap, I left the stove and canister outside overnight, at temperatures which approached or fell below 0 F (-18 C). The stove lit well in the morning, without any noticeable balkiness. I was quite impressed, though I did experience some problems attaching the fuel bottle, which wouldn't easily engage with the O-ring/locking mechanism. At the time I had ascribed this to possible clumsiness on my part, but I had the same experience on my next backpack, which was under winter conditions.
On this trip, with a group of friends (including one BGT stalwart) I did a snowshoe traverse of Panther Mountain in the Catskills. The night was fairly cold (20 F, -7 C), and we were camped on about a foot of crusted snow. Again, the stove lit well, but once more I had a little bit of a fight beforehand to get the fuel bottle attached. It did attach, but only after a couple of minutes of trying (I also warmed the O-ring slightly with my hand, which in harsher conditions would not necessarily have been safe or feasible). I didn't have much trouble in the morning, but the temperatures had moderated slightly overnight. This is an issue that I will be closely examining in the long-term phase of the test. Once alight, the stove dispatched quantities of snow very efficiently. I didn't see any significant variation in the intensity of the flame as fuel was consumed.
I contacted Coleman customer support anonymously about the issue with mounting the canister, to see if mine was a common complaint. Given that it was only a few days after Christmas, I was pleasantly surprised to be quickly speaking with a Coleman employee. She told me that this was not a documented issue with the stove, and suggested that I replace the seal assembly, to see if that improved matters. Once I hung up the phone, that was exactly what I did.
The replacement procedure involves unscrewing the three Phillips screws that hold the valve assembly together (the leg just pops out of its mounting holes first). The cam (this locks with the faceplate when the canister is attached) has to be pried off its brass cylinder with pliers, and the plastic faceplate then falls free. Although the quality of the photographs in the instructional insert that comes with the repair kit could be a lot better, I found the process pretty intuitive and straightforward regardless, though not something that I would care to do with cold, numb fingers (with gloves, forget it). All was done with a Leatherman multi-tool, on which I used the Phillips screwdriver, pliers, and knife attachments.
My stove uses a pair of O-rings. I was interested to note that the replacements in the kit were red rubber, rather than black, the color of the originals. My hope is that the new ones will be more ductile at low temperatures. as I'm pretty sure this is the root of the problem; the rings won't easily compress when cold. Reassembly was easy, and the canister attached smoothly to the completed valve assembly. I won't know until the next cold spell whether this replacement has helped.
In use, I found the stove stable, though I did need to be slightly careful that the legs were correctly deployed (as they don't lock into position, there is potential for instability if they are not correctly spread). The pot was retained firmly on the pot-rest, and overall I was extremely pleased with the performance of all aspects of this little unit. My only wish is that it were a few ounces lighter, but the weight is comparable with most liquid fuel (read winter) stoves, and it is in fact far lighter than many.
I did have occasion to use the Green Key to prepare a spent canister for disposal. This was extremely straightforward. It should be done outside, and there should be no flames in the vicinity. Although no gas was detected when I shook the can, a fair amount of hissing occurred as the small hole was punched (this is no more difficult than using a church key tool to puncture a can of juice, and works on the same principle). There was a brief but noticeable smell of gas. It was a pleasure to be able to toss the empty canister into the recycling bin. I wish all canister stoves had this feature!
Summary
The Coleman Exponent Xtreme stove has proved to be a well-performing winter stove so far. The fuel use is a bit higher than ideal (during the Panther trip, I used about 7 oz (200 g) of gas between snow melting, dinner and my breakfast drink). Still, this was using a small-diameter pot (I usually use at least a 2 L, 2 qt pot for serious snow-melting) and no external windshield. This is far from an ideal situation for a stove of such high thermal output. A great deal of heat is, I feel certain, being lost. Having demonstrated to my satisfaction that the built-in windshield is effective at deflecting most wind from the burner, I will now be using the stove within a snow pit (when feasible), with a larger pot, and with a foil windshield around the whole. I'll be interested to see how this changes fuel consumption.
Future testing Strategy
In my text above, I have discussed many of the concerns mentioned in the testing strategy section of the initial report. I will continue to examine these as the test continues. The biggest new issue is the ease of attachment of the fuel bottle to the stove at lower temperatures. I will carefully evaluate whether this is an issue of major concern, and see if there are strategies to prevent it. I'll also evaluate fuel efficiency with a full windshield, larger pot etc. At the end of the long-term test period, I will further use the kit to disassemble the stove and examine crucial areas such as the screen (which filters the fuel) and nozzle.
Pro:
- Easy control of heat output
- Consistent output, not dependent on the level of gas in the canister
- Easy disposal of empty canister
- Burns readily at low temperatures
Con:
- Somewhat difficult to attach canister to stove at low temperatures
I thank BackpackGearTest and Coleman for permitting me to participate in this intriguing test.
