MELTING SNOW: Fuel Efficiency and Boil Time Comparisons of Four Gas Backpacking Stoves in Winter Conditions
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John Macri
(JohnMacri) - F
A Vote For The Coleman Xtreme on 11/30/2005 08:04:35 MST Print View

Great information from all. I have tried most of the stoves mentioned and have decided the Coleman Xtreme is my stove of choice for winter hiking. This past weekend temp's ranged down to 11F and had no problems at all with the stove. I have used it in below 0F as well with the same results. Aside from a somewhat tricky canister insertion into the stove, the problems are almost non-existent compared to my buddy's white gas models mentioned here. He gave up on the Dragonfly and now uses his whisperlite/shaker jet model. Few problems for sure but not as easy to use as the Xtreme. - John

Edited by JohnMacri on 11/30/2005 08:05:56 MST.

Kenneth Knight
(kenknight) - MLife

Locale: SE Michigan
Snow melting: fuel questions on 12/15/2005 02:09:42 MST Print View

OK, I find myself with a question. Canister stoves are notoriously flakey in the winter. At least they are for me even in temperatures above 0°F with moderate winds. I can recall trips where a canister stove just plain did not work and the conditions were reletively warm and winds nearly nil.

So, what is it about the Coleman Xtreme and/or MSR Wind Pro stoves both of which use fuel canisters that enables them to work (or so it seems to be claimed) reliably at temperatures aroun 0°F (and perhaps below)?

On a strictly stock wieght comparison why should I not obivously go with the Wind Pro overr the Coleman Xtreme every time (no, I'm not going to modify an Xtreme or Wind Pro; I doubt I have the mechanical knowhow, let alone tools, to do it)?

** Ken **

Tony Burnett
(tlbj6142) - F

Locale: OH--IO
Snow melting: liquid propane!!! on 12/15/2005 07:41:47 MST Print View

In a word, liquid propane...

The Xtreme, by design, uses canisters that have a tube in them that draws up the liquid propane. Propane boils off well below 0F (-44F comes to mind???). This allows the stove to work at sub freezing temps.

The wind pro is "just as bad" as any other canister stove in the cold, **UNLESS** you flip the canister over which allows the liquid propane to leave the canister "first". Thereby behaving, more or less, like the native functionality of the Xtreme.

Edited by tlbj6142 on 12/15/2005 07:42:40 MST.

John S.
(jshann) - F
Re: Snow melting: liquid propane!!! on 12/15/2005 07:52:31 MST Print View

If the wind pro does work that way when the canister is upside down, aren't you going to get less use of a windpro canister once the liquid propane is used up?

Woubeir (from Europe)
(Woubeir) - F - MLife
liquid butane on 12/15/2005 08:01:49 MST Print View

Actually, it's because these stoves are able to take up liquid butane, not propane. Butane has a boiling point of more or less 32°F. In normal canister stoves vaporisation takes place inside the canister and once temperatures drop beneath 32°F, the vaporisation of butane slows down very fast (vaporisation of propane continues as long as temperatures are above -40°F).

In the Xtreme and in the Windpro in upside down mode, vaporisation of the liquid fuel takes only place in the preheaeter tube running over the burner head.

Edited by Woubeir on 12/15/2005 08:05:03 MST.

Michael Martin
(MikeMartin) - BPL Staff - MLife

Locale: North Idaho
Re: Snow melting: fuel questions on 12/15/2005 10:53:42 MST Print View

Hi Ken and John-

I'd like to add a little to Tony and Tom's excellent replies:

A liquid feed canister system (home-brew upside-down, or Coleman Powermax) has two cold-weather advantages over regular canisters. But first, some background.

Current generation canisters contain a mix of Propane and Isobutane, (plus sometimes regular Butane.) The problem with regular butane is that it boils at -0.5 degrees C. So if the ambient temp is below freezing, your fuel would not vaporize. Isobutane is better in that it has a boiling point of -11.7 degrees C. (Propane boils at -42.1 degrees C.) So, why not just use Propane in the canisters?? Well, Propane has a higher vapor pressure, so requires a stronger (heavier!) can -- like the giant cans used for car camping, or your backyard BBQ. So, in order to keep the small canisters light, yet still work at low temperatures, manufactures use the Propane/Iso blend.

This blend approach is not completely trouble free, though. The different gases in the canister boil off at different rates. So, as you run the stove, the Propane is used up first -- leaving behind the (iso)butane. This explains why partially used canisters are particularly bad in cold weather -- there is little propane left in them.

To make things worse, the fuel in a regular canister vaporizes inside the canister as the stove is run. This causes evaporative cooling of the fuel, lowering it's temperature. So even if you start off with a warm canister, after running it for several minutes, it will cool and it's output will drop off or stop. That's why canisters are problematic for things like snow melting where 30-40 minute boils are needed.

Ok, so what about the liquid feed canisters:

1) Since the fuel evaporation occurs outside the canister in a preheat tube prior to cumbustion in the stove, canister cooling is minimized during prolonged usage. This allows them to provide consistant output over long burn times.

2) The liquid fuel bled from the canister always contains close to the original mix of propane/butane. Because the fuel does not evaporate in the canister, the propane doesn't get used up first. This makes liquid feed canisters perform more consistantly over the life of the canister.

[If you just invert a regular canister to get liquid feed, the final 10g or so of fuel won't come out in liquid form and operation reverts more or less to regular gas-feed operation for the last few minutes of fuel use.]

Cheers,

-Mike

Edited by MikeMartin on 12/15/2005 12:01:53 MST.