cold weather performance upright canister

"I also wonder about just using two shorter pieces… both inserted into the flame and just run both vertically down the side of the canister instead of wrapping it around. The idea being that probably only the first inch of the wrap in each direction has any warmth left in it. Place the two vertical copper wires 180 degrees apart and just use some tape or a rubber band to hold them on?"

Thirty years ago, we used one piece of copper wire. We bent it at the midpoint and stuck that bend into the flame area. Then there were two wires coming down toward the canister. When they got to a midpoint on the canister, we twisted them one turn to lock them, and then bent the remainder of the wires in opposite directions around the canister.

Think of it this way. If the gas were cold and liquified and would no longer evaporate its way out of the canister, then where in the canister would it be located? I think that is where you would want to apply the very slight heat.

–B.G.–

"Thirty years ago, we used one piece of copper wire. We bent it at the midpoint and stuck that bend into the flame area. Then there were two wires coming down toward the canister. When they got to a midpoint on the canister, we twisted them one turn to lock them, and then bent the remainder of the wires in opposite directions around the canister.

Think of it this way. If the gas were cold and liquified and would no longer evaporate its way out of the canister, then where in the canister would it be located? I think that is where you would want to apply the very slight heat."

Thanks Bob… but that's about as clear as mud to me… sorry, must be my old geezer brain, but I can't visualize what that would look like :(

billy

I just figured you have to wrap it around the canister to get it to stay put and make good thermal contact. You could have a loop of steel wire around the canister and stick the copper wire between, but it'll be hard to beat 0.33 ounces for 20 inches of #14. I'm wondering if metal fatigue will cause copper wire to break.

I think if it made good contact with anywhere on the canister, it will flow through the canister material and contents to everywhere else.

Nick, you're getting in the way of an experiment : )

There are tradeoffs to any solution.

WG is smelly. The stove is heavy. I'm tired of singeing my eyebrows…

Inverted stove is heavy – until Roger's. It bothers me a little that you run liquid through the valve which can gum it up or particles can clog it. If you know how to take it apart then you can clean it, but there's a simplicity to an upright that doesn't have to be cleaned.

If you're above 20 or 25 F, then upright is good. You can extend that downward a bit with one of these tricks, or just get Roger's stove and don't worry about temperature, at least for any temperature any of us are likely to see.

I am currently on a several months long winter hike through Southern Europe where I regularly encounter below-freezing temperatures at night. As I use a canister stove this thread is very interesting for me.

So far I have solved the problem successfully by using a canister cosy but I am intrigued by the copper wire idea. But with my specific long term application I see one problem:

How do you transport the "device" in your backpack? Of course you can leave the wire around the canister and pack it into your pot. But what do you do with the part that sticks into the flame? In order to transport it you would have to bend the wire around the canister as well and then bend it back into the flame for cooking. Although this will work a couple of times I wonder how quickly the copper wire will break from fatigue.

Any ideas? Or am I completely on the wrong track with this assumption?

First of all, you need to be careful when using a cosy (or cozy) on a butane canister. If the canister is barely above operating temperature to begin with, it will cool off as the butane is used. The cozy may act to keep the canister colder. OTOH, if you start with a canister that is very warm from the inside of a sleeping bag, then the cozy may help retain some of that warmth.

If the wire device is made out of copper wire, then you can fold it up after each use and then re-form it when you get ready for the next use. I realize that is not optimal. Some copper wires can be folded and unfolded many times, especially if you do it slowly and without sharp bends. Solid wires will break earlier than stranded wires, but it was always solid copper wires that we worked with.

–B.G.–

It would take quite a bit of repeated, even intentional, bending in a very tight bend to break the copper wire. I would think it would need to be bent much more aggressively than I can imagine for this application. In any case, I would think it would be good for at least a week or two trip. You cold always take a new piece of copper wire for each trip.

Billy

I've thought the same thing, metal fatigue

Here it is in flame:

Here it is, bent over. Probably have to bend it a little more. Note that I did not bend the part where it's sharply bent:

I don't know that this is a solution, but just what I was thinking.

Another thing to do would be to have a loop of steel wire around the canister and stick the copper wire between steel wire loop and canister. Then You wouldn't have to bend the copper wire each time you stored it.

@Bob: I am aware of the cozy problem as I have been using it for months now. I warm the canister underneath my clothes next to skin for 15 – 30 minutes before using it so it is warm enough.

The problem with a canister cozy on this trip is that I never know what type of canisters I will find. Sometimes I can get screw top ones and sometimes only the blue Campingaz ones – but they have different sizes and I have to adapt the cozy with lots of ductape…

My trips last several months and a "life expectancy" of two weeks for the copper wire is definitely not enough for me. Especially since you don't find copper wires in road side trash any more. Getting a new wire during my trip is time consuming as I would have to find a Home Depot type store in villages that don't even have a little grocery store (I am hiking through Southern Spain right now).

I might buy copper wire for two devices and give it a try though to see how long it lasts.

Is there any type of wire that seems to be most durable?

#14 solid copper. Bob said he used a little thicker – #10

I got some out of the garage and stripped the insulation off of it. Intended application is for house wiring.

If you had around the canister a loop of #18 galvanized steel wire and wedged the copper wire between it and the canister then you wouldn't have the copper wire bending problem. Just a gradual bend to get it into the flame and you wouldn't have to bend/unbend to store it. I'm not sure if there would be enough contact between copper and canister.

Or you could wedge a strip of aluminum between steel wire and canister and bend it over into the flame. I did that but then Bob suggested copper wire which seems simpler.

"Is there any type of wire that seems to be most durable?"

In general, a copper wire is what you want. My experience was always with a #10 gauge solid wire. Others went with smaller ones and larger ones. Some went with a stranded wire, and that is likely to withstand much more bending than a solid wire. For example, when they wire up a new home, they generally use #10 or #12 solid copper, because it is installed and then never moved afterward. For a portable device with an electrical cord, they always use stranded wires, since those will be flexed a lot.

The problem is that I never found stranded wire to be easy to form into a tight bend. Solid wire always seemed stiffer. But, you only need a foot or two, so you can go crazy with copper wire.

In the old days, we used to keep a butane canister warmer in a hanging configuration by holding a candle flame to it whenever it started to slow down. Obviously, if you get the metal seam too hot, it will get quite exciting. The heat of a candle flame for five seconds every minute used to keep it going normally.

–B.G.–

Or… you could get some sheet copper and cut a strip, maybe 1/4" or 1/2" wide and run that down to and between the steel wire wrapped around the canister and the canister… no bending of copper at all.If concerned about the flat strip affecting the flame you could fold/roll just that part that enters the flame to make it more aerodynamic…

Bob: I'm pretty sure that standard gauge for wiring a house in CA is #14, though some will up size to #12… but most are wired with #14…

Billy

Billy, that may be the standard now.

Some homes were built years ago with different building codes, so they have different wiring inside. My home is all-electric, so there are some big aluminum wires running to baseboard heaters and different copper wires running elsewhere. It seems as though they changed the wire gauge whenever copper prices would fluctuate. Plus, whenever there is a war and lots of brass is needed for shell cases, that needs copper, so that drives copper prices up which sometimes alters the building codes wrt copper wiring.

–B.G.–

"In general, a copper wire is what you want."

A possibility for transferring more heat: http://www.pexsupply.com/Holdrite-101-18R-1-2-Copper-Stub-Bracket-w-extruded-holes-20-Length.

Tom, that looks a little heavy. Remember, this is BPL.

–B.G.–

What about this – a piece of wire, folded in half, bent to sit in the flame at top, running straight down the side of the canister. A rubber band holds it tight to the canister. You wouldn't have to bend the wire each time you set it up. Question is whether the wire gets hot enough where the rubber bands contacts it to damage the rubber band.

Silicone band?

"Tom, that looks a little heavy. Remember, this is BPL."

It's not that bad for, say a 6" strip from the flame down the side of the canister. Maybe an ounce or so. Remember, it's perforated, but still has a lot more surface area than a wire. Just a thought for cold weather, where you could use a bit more heat on the canister.

"Question is whether the wire gets hot enough where the rubber bands contacts it to damage the rubber band.'

The way it works on my burner, the wire is hot only at the top. By the time it gets down to the canister, the heat is barely perceptible unless you leave the wire in the flame for a very long time.

Also, some people detach their canister from the burner when they break camp just in order to get everything to pack more compactly.

–B.G.–

Hi Bob..

I know… getting far afield from the intent of this thread, but I can't resist… or have too much time, I suppose. Anyway,,,

Yes, I'm sure there is a history of wire gauge codes with a bit of variance. But I assumed you were talking about houses now.

In any case, yes, houses have larger wire gauges for electric appliances such as electric range, heaters, cloths dryer, air conditioner, etc… and anything with a motor because they draw more current.
But when an electrician makes the generalization that his is going to wire your house with 14 gauge, he is talking about the majority of the wiring which is in the overhead lighting and the wall outlets. I'm pretty sure that current CA code is for minimum 14 gauge for normal overhead lights and wall outlets. And I believe it's been that for several decades… at least since the 60's or 70's.

Each appliance has it's own spec for gauge… so, yes, you can have 6 or 8 gauge for your electric range… and maybe 0 or 2 feeding the main breaker box… but the majority of the wiring in the house will be 14 or 12..

Billy

I used to have to deal with 0000 copper, but that has nothing to do with ultralightweight backpacking.

–B.G.–

German tourist…maybe you could get away with (2) upsidedown "L" shaped piece of copper. Long leg in the cozy and short in the flame. How well it works will depend on how tall and tight your cozy is.

I think cozies work well enough at extending cold weather performance as long as:
•you prewarm
•you aren't cooking for too long and
•the canister isn't too empty(as it empties there is less thermal mass to drive evaporation.

Another option that ive had success with is:
•turn canister upsidedown and fill the bowl with water.
•put cozy or other container on top and flip over.
Now run as usual with the water providing supplying heat from below.

Okay, a couple more cold mornings so a couple more data points

First, at 20 F, both the Jetboil isobutane and Burton canisters behaved the same – took 9 minutes to go from 9C to 90C. Since I'm a cheapskate, I might pick up some more of the Burtons – must be isobutane.

isobutane – time to boil – SOTO Windmaster stove – amount of fuel about the same for each case:
20 F – 9 minutes
23 F – 6
26 F – 3:40
32 F – 3

Operating at 20 F is pretty marginal, maybe 23 F is better.

Then I tried both an Al strip and #14 copper wire at 23 F when it was windy – 2 MPH gusts. They made little difference. Conclusion – when at cold temperatures you're even more susceptible to wind so you need good windscreen/sheltered location.

Then I tried 18 F in dead calm.

First I tried #14 solid copper wire wrapped around canister and up into flame. After 8 minutes it was only up to 70 C – I'de call this a no-go. Maybe Bob is right, #10 wire would be better and maybe it would help to flatten it.

Then I tried aluminum strip attached with steel wire wrapped arounde canister. 6" x 1 5/8". It's maybe 1/32" thick so that would be about 20 gauge. #18 steel wire. 0.5 ounces total. The cross sectional area of #14 is 0.004 in2. The cross sectional area of my strip is 0.05 in2, a little more than 10 x the #14 wire, so it should conduct heat more than 10 x better.

I tried it with the steel wire attached at the corners of the Al strip and it took 7 minutes. I moved up the holes a little, so it would better pull the strip against canister to make better contact and it took 5:30.

Conclusion is, if you use Al strip, you can operate at 18 F the same as 23 F without strip – this lowers your minimum operating temp 5 degree F.

If you look at that picture carefully, you can see three holes. The one that I'm using is what worked best. The one on the corner didn't work as good as described above. The third is in a little, but then the steel wire was between the Al strip and the canister so the strip made very poor contact.

So, you have to drill the hole maybe 5/8" up from bottom, as near to the edge as you can (1/8"), and you have to bend up the Al strip with pliers so that there's a space for the steel wire and the Al strip makes good contact with canister.

This was all with a mostly used up canister so most all the propane was gone. Another technique to operate at cold temps is to use new canister that has all its propane.

Maybe the technique of putting canister in water would work better. Cut off milk carton bottom weighs 0.7 ounces:

You could occasionally take some of the water you're heating up and put it in water container to keep it from freezing. As long as it's above freezing it should work good.

Jerry,
great info…

I wonder about two things:
1) using aluminized duct tape (like they use on the exhaust joints of a water heater)to hold the aluminum sheet strip nicely against the canister side…

2) would there be a way to use both the flat metal strip AND sit the canister in a small amount of water… (and how long would the water last without freezing solid????)

Billy

actually, on second thought, regular duct tape might be better as it would offer more insulation to help the heat go into the canister rather than into the air…

I'm assuming, of course, that the metal strip does not get so hot as to compromise the tape…

I would try it here today, but we're at 2 F this morning… And I have a migraine so not likely to be up for a project…

Billy

Jerry, thanks for the testing effort the information is nice to have.

Last night I came up with a new way of trying to keep an upright going in cold. So you find a flat, smooth piece of something light that happens to be larger diameter than your canister. Below I have the lid to a child sized tupperwear bowl but a dried oatmeal lid works well too.

Now invert the canister and fill with water. The msr canister will hold about 100gram water.

Now, while still inverted, place the the lid on the bottom of canister and press in the center to release any air and provide a bit of a vacuum seal when you turn it all right side up.

1gr if 32f liquid water will give up enough energy to boil 1gr of isobutane as the water freezes. So 100g could go quite a ways depending on what the heat loss to ground and out the wall of the canister end up being.

Somebody with some cold weather should give this a try(hint hint jerry) so I don't have to wait for the next cold spell to find out how much this set has to offer.