Field and test information
With the eighth warmest January on record, and an almost equivalently mild February, this has been an unusually temperate winter thus far here in New York State. Daytime temperatures have occasionally been as high as 60 F (16 C), down to perhaps 15 F (-9 C). Nighttime temperatures have lacked their usual bite. There has also been little snow in the LTR period, though there's been an unusual amount of rain for this time of year. The one major snowstorm of the period missed us, and clobbered New York City instead. Elevations at which the stove was used varied from 500 ft (152 m) to 4000 ft (1219 m), sometimes in heavily wooded settings.
Product Use and Performance
The Xtreme Stove (courtesy Coleman)
I had hoped that I would be able to test this stove in the bitter cold of a true New York State mountain winter, but conditions have frequently been closer to spring this year! As a consequence, in the Long Term Report period I've only been able to test the Xtreme Stove in the field (with several backpack trips to local peaks) in what I would really consider only moderate cold, down to around 15 F (-9 C). At these temperatures it has operated extremely well, lighting easily and providing a strong flame. It has proved a great stove for snow-melting (we do have some snow at elevation, thank goodness), as well as routine cooking.
As the weather has not been sufficiently cold for determining true low-temperature performance, as I had wished at the outset of this test, I have had to resort to "bench tests" to emulate performance in colder environments. I've cold-soaked the stove and canister overnight down to around 0 F (-18 C), using my big food freezer. I'm happy to report that the performance at such temperatures also seems satisfactory, although I have a few caveats, as noted below. The stove is still easy to light when cold, and, once it has run for thirty seconds or so, it performs like a blowtorch. If the weather during what's left of our winter provides an opportunity for more testing in the field at low temperatures, I will provide an addendum to this report.
So far as I am able to judge, the stove performance is uniform, or close to it, whether a new canister or one substantially empty is being used. The stove burns well until the canister is exhausted. There's no liquid gas detectable by shaking the canister, something that's borne out when it is opened with the Green Key for recycling. The amount of gas remaining in the canister causes some slight hissing on opening, but no more than that.
I have had some continued problems attaching the canister when both it and the stove are cold, despite replacing the components of the valve assembly as detailed in the Field Report, a procedure that I had hoped would address this issue. There seems to be some improvement, but I still have to exercise what seems like undue effort before the canister can be twisted to lock it in position. If the stove and canister are being truly stubborn, I have found that it helps if I warm the valve assembly slightly under my arm. This doesn't on the face of it seem to be a major issue, but it can be a tad irritating in the field. It is conceivable that it will become progressively easier as the stove receives still more use and the valve components compress or wear, allowing a little more play, but this is speculation only.
Also of note, I've had one of the two replacement probe seals (these are gaskets between the canister and the stove valve) come off when the canister is being removed. These tiny seals are held in place only by friction, and unfortunately the absence of one is not something that's at all visually obvious. The good news is that there seems to be no gas leakage even if one strays. To test this, I immersed the entire valve assembly in water with the canister attached, and there was no evidence of any escape of gas. Still, this was a little disquieting.
At low temperatures the stove burns a trifle irregularly for the first thirty seconds or so (only when it's very cold). There's some initial sputtering in this circumstance, presumably as the pre-heat tube warms up. This quickly goes away, and it doesn't seem to represent a significant concern, at least within the temperature range at which I have been able to test.
Though the built-in windshield, which cups the burner, helps shield the burner to a degree, I have found that using an external foil windshield is very useful (to the point of being essential) when there are strong cross-winds. I've tried using the stove without this when it's windy, but boiling times appear significantly slowed and there's obviously a great waste of fuel. I now use the stove without a windshield only in comparatively still air.
What follows are my original questions from the Initial Report, with my commentary, based on my experience with the stove.
1. Efficiency: How efficient is the stove at low temperatures? Does it light easily (both in warm and cold)? Does the flame burn cleanly, without flare-ups? Does the strength of the flame vary over the life of the cartridge? Does the flame pattern lead to any serious hot-spots? Is this an effective stove for snow-melting? How controllable is the flame; will it turn down low for simmering (a failing with many otherwise excellent stoves)? How long will a cartridge last with this stove under varying conditions?
COMMENTS: The stove pumps out a lot of energy when going full-bore, and it's important to use the control valve to moderate the flame. The stove does light easily and cleanly, and I've found the flame consistent, other than some slight irregularity immediately after lighting, and that only at low temperatures. I've not noticed any decline in heat output over the life of the cartridge, and the burner is well designed, with no serious hot-spots. A fairly small pot, such as my MSR Kettle, is quite practical, although for maximum efficiency a larger pot is desirable (there is slight flame leakage with a small-diameter pot on all but the lowest settings). This is a dandy stove for snow melting, but it serves equally well for simmering, or for cooking. My experience has been that under winter conditions, a single large Powermax canister will serve for both cooking and snow melting for at least two days, and (with care, use of a windscreen, and a large diameter pot to maximize efficiency) possibly three.
2. Utility: Does the stove assemble swiftly and easily, with easy movement of the legs? Is assembly also straightforward with gloved hands? Can I be certain that I have a tight seal to the canister? Is the stove stable on its tripod legs under different loads, and the pot secure on its supports, (a couple of liters of snow melt can put quite a strain on a stove)? Do I need to warm the cartridge for optimum performance at low temperatures, and if so, what's the best way of doing so?
COMMENTS: Assembly is easy enough, although attachment of the canister may prove a little awkward at low temperatures. The stove legs spread easily; actually, a little too easily for complete comfort, as a couple of times I've accidentally nudged them out of position. Provided that there is a probe seal visible in the valve assembly, I can be confident of a tight seal, although it is possible for one to become dislodged, and visual inspection is therefore important (though this is true to some degree for any stove). So far, I haven't had to warm the cartridge, but I haven't been able to test in the very coldest conditions.
3. Durability: Will I need to use the repair kit in earnest? How easily may field repairs be conducted? Can repairs be done in gloved hands? Will it stand up to the usual abuse of camping? Will spilt liquid (boiling over, etc.) cause corrosion problems?
COMMENTS: So far, I've had one occasion to use the repair kit, but not in the field. Given the small size of some of the parts, this is work best done with bare hands, or perhaps very thin liner gloves at a pinch. There's no significant wear and tear to the stove evident, and there are no corrosion problems.
4. Packing: Does the stove fold down to a small, neat size? How much room do the Powermax cartridges occupy, and do they need any special protection? How easily and safely are the empty cartridges recycled?
COMMENTS: The packed size of the stove is fairly compact, and the canisters fit well into the outside pockets of some packs. The canisters appear very strong, and are not in need of any special protection. Preparation for recycling is quick and easy, but should certainly be done outside, away from a flame.
Summary
This is a solid cold-weather canister stove, and I'm generally pleased with it. In comparison with most standard canister stoves when used at low temperatures, the performance is comparatively worry-free, largely due to the liquid feed technology. I do have a few low-level concerns, especially in regard to the attachment of the canister.
