The Coleman Xtreme canister stove is arguably the best winter canister stove on the market, outperforming almost any liquid fuel stove around. It is very easy to use, highly reliable, emits a negligible amount of carbon monoxide, and does not die in the cold. Its only downsides are the special Powermax canisters (which are however fully justified) and the weight - more than an upright canister stove but still less than for liquid feed stoves.
- Liquid feed works below -20 C (-4 F)
- Easy to operate
- Can provide any power level from gentle simmer to snow-melting roar
- Very low carbon monoxide emission at all power levels
- Stable design
- Very reliable
What's Not So Good
- Heavier than summer canister stoves
- Powermax canisters not globally available
|2006 Xtreme (eXponent range)|
|4.1 kW (14,000 BTU/hr)|
|11.0 oz (312 g), magnesium, stainless steel, brass, braided fuel line|
Stove leg radius
|100 mm (4 in)|
Stove pot support radius
|75 mm (3 in)|
Stove pot support height
|110 mm (4.25 in)|
|Claimed: 180 x 100 x 100 mm (7 x 4 x 4 in)|
Burn time (on high)
|1 hr for 300 gram canister|
This is a specialised canister stove designed for very cold winter conditions. It has a three-legged burner and a 140 mm (5.5") flexible hose leading to a remote "Powermax" gas canister. These Powermax canisters are designed for this series of Coleman stoves, and both the shape of the canister and the connector are different from the standard screw-thread canisters. The stove has a pre-heat or "generator" tube just before the jet. This makes the Xtreme usable in the snow under conditions where an upright canister stove would quickly die.
The construction uses magnesium, brass and stainless steel. The stove has three magnesium legs, each with a flattened tubular serrated stainless steel pot support. These legs rotate together to fold up for packing. They open out to positive stops to give a support diameter of 150 mm (6"). The curved shape of the pot supports is meant to prevent pots from sliding off, and is quite effective. The bottom ends of the legs have plastic feet which are moderately effective at preventing slipping. The manufacturer advises that the diameter of the pot should not exceed 200 mm (8") and the weight should not exceed 3.6 kg (8 lb). That's a pretty big pot.
The hose between the stove and the control valve is made of heavy rubber sheathed in braided stainless steel and the ends are protected by heatshrink tubing. Despite this construction it is more flexible than many others. The valve assembly is cast magnesium and includes the connection to the Powermax canister. The valve is on the liquid side of the pre-heat tube. The coupling houses a conventional needle galve that is activated by the large black knob. In summer time it is very likely that the valve will take liquid from the tank and let gas out into the fuel line, but in winter it will have liquid in the fuel line.
In the photo above the fuel line and its connection to the stove look rather innocuous. They are not. The straight bit of the fuel line under the stove is more than just a brass tube; it also contains a thin brass rod which fills a lot of the volume. While Coleman don't say why this rod is there, I believe it acts as a secondary restriction on the flow of liquid fuel and also as a heat exchanger. This combined role helps to convert the liquid fuel to a gas in a controlled manner by damping the flow down. Without such an arrangement the flow in the fuel line can oscillate back and forth in a disconcerting manner, a behavior I have observed with other stoves during experiments. The flow of fuel in the Coleman Xtreme seems to be nicely stable.
A nylon packcloth bag is provided with the stove. The stove legs have to be collapsed together and the hose has to be folded around the body to get the stove into this bag. However, the bag is heavy and I have replaced it with a lighter one. The instructions which came with the stove were in English, French and Spanish. They were fairly comprehensive.
Powermax Fuel Canisters
A Powermax canister cut open to show the feed tube
The Powermax canister is included in this review because you can't run the Xtreme stove without one; they have been designed to work together. The Powermax canister looks like, and likely is, a slender anodised aluminium hairspray can. Being made of aluminium it is light - much lighter than the steel shell used for the more common screw-thread canister. It has its own version of the "push and twist" connector that is different from the other "standard" cartridges on the market (screw-thread and CampinGaz). That is why there is a hexagonal hole in the black plastic, shown in the photo under Reliability. It grips the spigot on the canister to provide the 'twist' part of the connection. I find it is easiest if I hold the valve in my left hand and the canister in my right hand, push the two together firmly, and then twist with my right hand for a quarter turn. The action is quite definite and the connection is positive.
|Large Canister||Small Canister|
|Nominal Contents:||300 g (10.6 oz)||170 g (6.0 oz)|
|Gross Weight:||386 g (13.6 oz)||240 g (8.5 oz)|
|Canister weight:||86 g (3.03 oz)||70 g (2.47 oz)|
|Diameter:||65 mm (2.6 ")||65 mm (2.6 ")|
|Length:||220 mm (8.7 ")||135 mm (5.3 ")|
|Gas Composition:||60% butane, 40% propane|
|MSRP:||Not found on web site|
I believe the choice of a unique connector was done deliberately for some good interlocking reasons. Briefly they are as follows, but I will enlarge on these later.
- First, the basic concept of the Coleman Xtreme requires a liquid feed for proper operation in the snow. Using a gas feed would result in the canister chilling down (as with other upright stove) and soon not working any more.
- Powermax canisters are specially designed to provide a liquid feed when lying on their sides. They have an internal feed tube which draws fuel from the bottom of the canister as shown here. A screw-thread canister would have to be tipped upside down to provide a liquid feed like this (this has since been done with the Coleman Fyrestorm stove).
- Putting a screw-thread fitting onto one of these Powermax canisters might (would!) result in someone using one with an upright stove and getting liquid butane/propane mix out the jet. This would yield an extremely dangerous fireball - and many lawyers.
My understanding from Coleman is that the Powermax canister contains a 40% propane / 60% butane mix. This mix should let the canister work down to almost -26 C (-15 F), although you would be well advised to try to warm the canister up a bit when you are down near those temperatures! You can safely warm a canister to near body temperature, and it certainly will work a lot better if you do. Anyhow, this gas mix is quite similar to a mix of 30% propane / 70% isobutane, and as far as I know these two mixes are the best available for cold weather apart from straight propane. However, straight propane does not come in these lightweight canisters: its vapour pressure is far too high. For more information on this see Exploding Gas Canisters: The Dangers of Overheating.
Morning coffee is coming ...
Our normal practice in reviewing a piece of gear is to first use it in the field for while. We did the same with the Coleman Xtreme, except that I have been using one of these stoves in the snow for about six years. I think I understand it rather well by now! I graduated to it from a kerosene stove, and after my first trip with it never looked back. The reasons for my "conversion" are quite simple:
- I can set the stove up and get it running in under a minute - contrast this with the time it takes for a white gas or kerosene stove.
- It does not flare up when I light it - contrast this with the typical white gas fireball.
- It has more power than any white gas stove around.
- Despite the high power available, it can be turned down to a very gentle simmer - unlike most white gas stoves.
- It emits very little carbon monoxide, so I have no qualms about using this inside my tent in any weather.
- It is lighter than any white gas or kerosene stove.
- It doesn't smell, unlike a kerosene stove.
Setting this stove up requires just two actions. First, I open the three legs out into the tripod arrangement. That takes a few seconds. Then I connect the valve to the tank, which requires that I push the two together and then twist the tank a quarter turn. This normally takes me about ten seconds, although I am aware that a few people have reported problems making this connection in very cold weather. When I enquired about this I was told that Coleman was aware of the reports, but their staff had not been able to reproduce the problem. Anyhow, if the connection is not made correctly, you just don't get any gas out, which is safe. If this happens, undo the connection and try again. I have not had this problem myself once I realised that I need to press the valve and canister together with a little bit of force in the cold.
Anyhow, that means I can have the stove set up and ready to light in about 20 seconds. Contrast this with the drama of getting a white gas or kerosene stove ready. Actually lighting the stove is very simple, but I always take it gently. First of all, don't expect there to be gas the instant you open the valve: you have to flush the air out of the hose first. This takes a couple of seconds. For safety reasons I usually have a flame at the stove waiting for the gas to arrive: it does no harm to be careful. Also I don't crank the valve wide open right at the start: I open the valve a little bit, light the gas, and let the preheat tube warm up for about 10 seconds. Mind you, I usually put the pot straight on the stove once it is lit: no waiting around ages for "priming." There is no fireball period with this stove.
Cooking dinner in the tent with poor weather outside
You will see from the pictures that I always use a windscreen around the stove. That's reality as well - when the wind is blowing you simply have to use one if you want your pot to boil. In this case of course the canister is outside the windscreen, as with the common white gas and kerosene stoves which come with windshields. I find it useful to orient the windscreen so the gap points towards the canister, and to insulate the canister from the snow. This lets the canister warm up a little from the radiation from the stove, which keeps the pressure inside the canister up so the stove works well. Of course I monitor the temperature of the canister while I am cooking and don't let it get hot to the touch at all. Since the canisters have to take storage up to 50 C (122 F) this is quite within the manufacturer's specifications.
The stove has three legs, with little plastic padding at the ends. This is fine on a hard surface, but not so good on a soft surface like sand or snow. You will note in the photos that I have a little disk of rigid 3-ply wood under the stove in the snow. I recommend that you use a similar platform to prevent accidents from happening. Light aluminium foil is just not rigid enough for this job.
The really great thing about this stove in my opinion, unlike some other stove, is the very low level of carbon monoxide emitted. This applies at both a gentle simmer and full power. Of course I make sure there is good ventilation above the stove when I use it this way. You can see the open tent door above the stove in each of these photos. The almost hysterical warnings given by some stove vendors about never ever using a stove inside a tent must have been written by someone living in fairyland - they are simply unrealistic. I am not going to sit outside in the bad weather to cook my dinner! I expect my stove to be clean and safe for use inside a tent, and in my experience the Xtreme is.
Finally, I have to add my wife's comments on the subject. White gas frightens us both - we have seen too many accidents in our time, so for many years I used a kerosene stove in the snow. It stank the tent out, and my wife, sitting as far as possible up the back of the tent, used to complain very quietly about the smell. Since switching to this Coleman Xtreme stove I have not heard a single word of complaint about any smell. In fact, these days I am far more likely to hear something like "Where's dinner?"
Dinner cooking as the sun goes down
I don't conduct machismo-laden boiling-time competitions. Running a stove absolutely flat out simply sends most of the heat up the sides of the pot, where it is wasted. I'm carrying that fuel! I am far more interested in using my stoves intelligently and economically. Coleman claim a boil time of 3 minutes for 1 litre; I would normally run the stove to get a boil time of about 6 minutes. What difference does 3 minutes make anyhow?
This stove is rated to 4.1 kW (14,000 BTU/hr), and that is far more than I shall ever need or use, and more than most any other light stove I have seen. Suffice to say that this stove will match or exceed most any other stove I have tested for power output - and that does include white gas and kerosene stoves!
Popular myth has it that you must have a white gas stove to get good snow-melting power, and that canister stoves don't have the power. Well, I have yet to find a white gas stove which can put out 4.1 kW (14,000 BTU/hr)! As discussed in Selecting a Canister Stove for Cold Weather Backpacking Part II: Commercially Available Canister Stove Systems, the butane/propane fuel used in canister stoves is not fundamentally different from white gas as a fuel. The canister stoves just have more power! Perhaps I should add here that the myth probably comes from attempts to use an upright screw-thread canister stove, or even one of those old Bleuet stoves, in the snow. They are not winter stoves, but this one is.
While the Coleman Xtreme can roar, it can also be turned down to a very low simmer. It is after all a canister stove. Getting the fine control requires a little more care than with an upright canister stove. The valve works on the liquid flow, so I need to turn the valve down gently and monitor the change in power. But then, you should always monitor your stove while using it. A change at the valve can take about 5 seconds to be fully effective at the flame. Nonetheless, I can get the stove turned down so low that an open pot over the flame will slowly come off the boil and start cooling down on a cold night in the snow. That is a low flame!
The crucial connector and O-rings
As I said above, I have been using one Coleman Xtreme stove for our winter trips for about 6 years now. In that time I have done zero maintenance in the field on it. At home I have gently removed the little black O-ring shown here and greased it with silicone O-ring grease a few times, but that is all. I use a wood toothpick to extract the O-ring: no sharp metal points or edges which might damage it please! Look after this little O-ring: it's what stops the gas from leaking out when you use the stove. Because I am paranoid, or maybe just careful, I carry a spare O-ring in my repair kit as well, but I have never needed it.
I mentioned above that you have to squeeze the valve/connector and the canister together with a bit of force to get them to mate properly, and that some people have in the past had some problems here in the cold. I explored this problem some years ago and came to suspect that it might be partly due to the cold making this little O-ring harder, and I passed this comment on to Coleman. Rubber does after all get harder in the cold. I notice that the latest version of the connector is slightly different from the old one: it now features two O-rings stacked up on the small tube. You can't see the second O-ring: it is embedded in the brass backing which is visible beside the O-ring. It seems they have just hollowed out a ring around the tube to make the necessary space. Having two O-rings there makes it a bit easier to push the valve/connector onto the canister. It is nice to see that Coleman is willing to fine-tune their designs like this.
I did wonder whether the stove could have been made a little lower to the ground, to get more stability and perhaps slightly less weight. To be sure, the legs could be shorter. However, this is a powerful stove, and if it was placed too close to the ground the heat radiated downwards might become a hazard. The small cup under the burner does block some of the downwards radiation, but the flames spread quite wide at full power, beyond the reach of that cup. I think I will leave it just as it is.
- The first genuine liquid feed canister stove really designed for winter use
- The extremely low CO emission level
- The sheer reliability in the field
- The special lightweight Powermax canisters (although these can be harder to find)
Recommendations for Improvement
- Reduce the weight even further
- Put a swivel on the fuel line