Any advantage to using cozy for butane/propane stove canister?

That depends on the starting temperature of the canister. If you have managed to keep it warm, then it may well be useful. If it's already at ambient, you won't achieve anything.

Cheers

You know how water or frost will form on a cannister when the stove is running? Putting a foam cozy around the cannister is a good way to keep that cooling effect around the cannister and not let it escape to the air. You might end up with the cannister frozen to the cozy.

A simple way to keep cannisters warm while the stove is operating is to place the cannister in a pan of water. Or tape a heat packet to the bottom–Primus once sold packs for just that purpose.

The only thing I've ever done to keep a canister warm is to take it out of my pack and put it inside my insulation jacket against my stomach/chest a little bit before use. I doubt this was necessary with our Coleman Xtreme, but it could only help. In this case, wouldn't wrapping a thin cozy around it be useful?

And if not a cozy fully covering the canister, wouldn't a piece of insulative material between the canister and snow be helpful?

EJ,
You have the same thinking as I do and it would work (I think) theoretically with the right conditions.

1) The canister is warmer then the surrounding air

2) It is stinkin' cold outside

The cozy will not allow the cooling effect escape to the surrounding air. True statement, however, this is assuming the surrounding air is warmer then the cooling effect of the canister or the canister itself. Ex. If the temperature is -30*F (-34*C) then I want to isolate the canister (which is warming in my jacket) from that air (ie. CCF cozy). At some point, the canister will chill to below it's operating temperature and you then want to introduce heat to it at which point the cozy would have to be removed.

Just this weekend I used my extreme in a small pool of cold water and the performance increase was amazing. And the water really was cold – not even warm. So in the end, I think that is the best solution.

Carter, odd that you mention the heat pack on a canister. This weekend I brought a couple of them for my toes and my buddy asked if I could just put one under the canister. I thought "what a great idea" but didn't try it as it as sitting in water. So now, I wonder if a heat pack INSIDE a cozy would be beneficial? I melt snow at night, so I could use the heat packs for the canister and then throw them in my socks afterwards for the remainder of the night…

Has anyone done this? Or did I invent the greatest winter canister setup ever?!

I believe that wrapping a cozy around a canister would be beneficial for a liquid feed stove when it’s cold enough out.
When sufficiently cold out: The canisters on a regular upright stoves (gas fed), will cool as the liquid fuel evaporates in the canister (b/c the liquid needs energy to turn to vapor). Depending on how cold it is the ambient and the ground will usually counteract this effect.
The fuel canister on an inverted stove (liquid fed) shouldn't cool b/c of evaporation since the evaporation is occurring in the preheate tube and not in the canister. The inverted canister would, though, cool b/c of the cooler air and the cooler ground; a cozy would slow this cooling.

James, you are absolutely correct. In cold weather an inverted (or horizontal Coleman style) iso-butane canister WILL benefit from a cozy, and especially a cozy with a small chemical "toe warmer" pad, so as not to overheat it.

An upright canister will, of course, cool the canister somewhat, so maybe a hand warmer sized heat pad is called for in that situation.

And Roger Caffin has a great instructional on this site for making an inverted canister stove. What's nice about the instructional is that is has been thoroughly tested and optimized with the most appropriate materials.

So Roger, what's the verdict?

In say 15F weather, wouldn't a Powermax canister warmed inside your jacket for a while benefit from a cozy?

A gas canister (any type) will benefit from a cosy only _whilst_ its contents are warmer than the ambient temp.

So, a pre-warmed inverted canister will benefit: there is no evaporative cooling and the cozy will keep the contents warm(er).

However, an upright canister is cooled from within by evaporative cooling. If it has a cosy you will not know when it has cooled below ambient so any benefit of the cozy will be short lived and then becomes a disadvantage.

For both types, there is no benefit at all if the canister has not been warmed above ambient to start with.