cold weather performance upright canister

[Jerry Adams]

It's 23F here – coldest in 3 years I believe, so I measured a couple things

I used a Burton 8 ounce canister which is supposed to be Butane and Propane but I'm not sure. $2.50 for 8 ounces at Fred Meyer. Maybe it's just whatever happened to come out of the well.

I got a SOTO – the new Windmaster. There's a lot of talk about how SOTOs with their regulator work better at cold temperature, but no data just operating at specific temperature. Just video of filling up container with ice water or whatever.

So I heated up 15.6 oz of water with SOTO and Pocket Rocket – standard needle valve stove. Measured weight before and after to calculate fuel use. Measured temp before and after. I tried to get it to 90C but measured actual and normalized the data.

Test setup – cooking thermometer through hole in top:

SOTO – 9.2 to 93.3 C, 6.2 g fuel – 12.8 g/L/80C
Pocket Rocket – 11.1 to 93.1 C, 5.7 g fuel – 12.1 g/L/80C

They both took 6 minutes. It normally takes 3 minutes and uses about the same amount of fuel.

So, the SOTO and Pocket Rocket slow down by the same amount – SOTO offers no advantage at cold temperature. I think I'm getting down towards the lower temperature limit for this canister.

The fuel usage was a little less for Pocket Rocket, but that could easily be measurement error.

Of course, there's advantage to not having to adjust needle valve…

Then, I tried the trick of wrapping cooper wire around canister and the end into the flame. #16 wire I believe. 20 inches long. 0.33 ounces:

SOTO with wire – 10.3 to 94.7 C, 6.7 g of fuel – 13.8 g/L/80C

It took 3 minutes and 10 seconds. This is the same as at warm temperatures.

It did take a little more fuel. Could be measurement error but this is less likely because difference is greater. Probably it's because the flame was higher which makes it less efficient – more heat blows away into the air.

So, conclusion is for 0.33 ounces and some fiddling, you can operate at maybe 10 degree F colder.

[Stuart R]

The critical thing here is the temperature of the canister, which you do not mention, and the canister contents which change with use.

The copper wire obviously helps to transfer some heat to the canister, surprisingly given the tiny contact area, but how much heat was transferred from your hands as you fitted the copper wire?

As has been said before, the Soto regulator cannot make the stove work any better at the cold limit of the canister, but as you noted it can save having to adjust a regular needle valve.

[Jerry Adams]

I left the canister outside and waited 15 minutes between tests which seemed enough to stabalize – enough time to drink cup of tea – so the temperature should be the same for each test.

I just slipped the wire on, short amount of time to transfer heat. And without wire, it started fine but then slowed way down after a while from evaporative cooling. This didn't happen with wire, so enough heat must have been transferred to offset heat lost to evaporative cooling.

As has been said SOTO regulator can not make stove work any better – but that's theoretical. I thought just operating at low temperature would be a good data point.

Maybe tomorrow I'll heat my tea water in the reverse order to remove any effect from the fact that the proportion of propane in the canister is getting less because of operating at cold temperature.

[Roger Caffin]

Hi Jerry

> $2.50 for 8 ounces
That's awful cheap for a butane/propane mix – more typical of a straight butane canister. But anything is possible. Maybe the shop was getting rid of them?
I searched for *Burton* canisters and only found straight butane flyspray ones. Maybe Burton have discontinued them?

Are sure this was not Brunton? Just asking. EDIT: OK, Burton.

The copper wire trick is well known of course. You can maybe do ebven better with a strip of 1.2 mm aluminium shet, say 15 -20 mm wide, strapped to the canister and with the tip bent over into the flame. That's basically what I did in http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_winter_stove_summer_upright_stove_brunton_stnd.html

Has the SOTO any magic at all at low temps? Chuckle. Not a bit, as Stuart wrote. See also our review of the SOTO: http://www.backpackinglight.com/cgi-bin/backpackinglight/soto_od-1r_canister_stove_product_review.html where the same conclusion was reached. Spin, spin, spin.

Cheers

[Jerry Adams]

They sell Burton at Fred Meyers. That's a regional store, maybe 100 stores around the Pacific Northwest. I've seen the canisters at several stores in the Portland area over a period of more than a year. They must get a huge quantity. Very close to Brunton : ) Must be a Chinese company.

It says on the side of the can "clean burning premium blend of fuel" doesn't mention propane, butane, or isobutane. On the cash register receipt it said butane.

Maybe I'll try some isobutane for comparison – I have a Jetboil canister. But maybe the content of Burton varies depending on what they have available, so even if what I have is better, maybe the next batch I get will be just N Butane. Maybe the cheapest thing to do is just take whatever's available "from the well".

They sell them here http://www.hardwareonlinestore.com/sporting-goods/camping-appliances-fuel/propane-butane-cylinders_84903/fuel-blend-cartrdg-8-1oz-detail?gclid=CLWSgbHol7sCFWhxQgodfQcA4A $2.60 each for 12 of them, I don't know about shipping cost – I don't want to enter my address.

I tried aluminum sheet but maybe it was Bob Gross that mentioned copper wire that was in some book, which is simpler. I wanted to actually try it in cold weather.

I agree theory says SOTO can't be better – physics of evaporation. But still, nice to experimentally verify.

[Bob Gross]

"I tried aluminum sheet but maybe it was Bob Gross that mentioned copper wire that was in some book, which is simpler. I wanted to actually try it in cold weather."

Sheet aluminum will work, and copper wire will work. We used to take a #10 AWG copper wire and flatten it somewhat with a hammer. Flattening the copper makes for more surface contact at the canister end, but we used to keep it pretty short.

–B.G.–

[Nick Gatel]

I have seen bUrton stoves and canisters at discount places like Big 5 Sporting Goods. A long time ago I checked into the canisters and they were something like iso/pro 70/30. Don't know if yours is the same.

[Jerry Adams]

Since mine was working at 23 F, it must not be very much N butane. It took 6 minutes to boil rather than the 3 minutes at warm temperatures.

Maybe for $2.50 I'll buy some more, but they tend to sell out in the winter. I don't understand why people don't backpack in the winter, it's actually much nicer now, you don't over-heat.

[James Marco]

Hey, Jerry, try some aluminum wire from a house feed line. I believe this is 10ga wire and conducts heat almost as well as copper, but is lighter. (Not used for hook-up wire, but for the main feeds on panels, like 500 amp.)

[Larry De La Briandais]

If anyone is interested, shipping is $16.36 bringing the price to $4 per cartridge, but you have to purchase 12.

Added: BTW, I did not order them. Shipping made them too close to the cost of local name brands.

[Jerry Adams]

$4 is closer to the $5 or $6 that brand name canisters cost. And those reliably have isobutane and no contaminants, Burton is a bit of a crap shoot

[Bob Gross]

"some aluminum wire from a house feed line. I believe this is 10ga wire and conducts heat almost as well as copper, but is lighter"

Not exactly. The thermal conductivity of copper is almost twice as good as aluminum. Aluminum is lighter, but the mass of metal that we are using here isn't much in either case. The decision over one metal or another metal should be based on what you have laying around for scrap. If you use any wire, then the tip of it that extends into the flame may melt and drop off.

–B.G.–

[Jerry Adams]

"but the mass of metal that we are using here isn't much in either case."

the 20 inches of, I believe, 16 guage copper weighs 0.33 ounces so if aluminum was a little lighter it wouldn't make much difference

[Bob Gross]

Jerry, I don't think that you will get much good out of single 16 gauge copper for this. I wouldn't even think of doing it with anything less than 12 gauge, and 10 gauge is what we used to use thirty years ago.

If you leave it in (round) wire form, then it won't have much surface area to touch the canister. On the other hand, if you used the same mass of metal in a thin foil, then it will have so much surface area that it will radiate heat all along the length. So, we used to flatten copper wire with a hammer to get to a mid-point, maybe with the wire flattened to half thickness.

One guy got carried away. He flattened his 10 gauge wire, and then he kept rolling it and flattening it to a foil thickness with the idea that it would touch the canister best. Unfortunately, he got it so thin that the metal was weak. Once it broke off, then he had nothing.

–B.G.–

[Jerry Adams]

Okay, enginerring toolbox.com – 14 gauge wire weighs 12.4 lbs/1000 ft – I have 20 inches so that should be 0.33 oz, which is what mine weighs, so I must have 14 gauge. Plus my wire stripper "wire gauge" shows it's #14. #16 cuts into the wire. #14 has some air space between wire and stripper.

10 gauge would weigh 0.84 oz which is insignificantly heavier so that would work too.

With my 14 gauge not flattened, at 23 F, it took 3:40.

At 40 F without wire it took 4:00, so maybe the 14 gauge wire lowered the temperature it would work at by 17 F.

So if all you need is 17 F of temperature difference, then #14 un-flattened is good enough. If you need more than that, then thicker wire would be better.

Maybe transmitting the heat from the flame down to the canister is more important than conducting it into the canister. So flattening it wouldn't make that much difference. The wire wasn't real hot to touch where it made contact with canister.

[Bob Gross]

"Maybe transmitting the heat from the flame down to the canister is more important than conducting it into the canister."

How are you going to transmit heat if you don't thermally conduct it by wire?

You could use a mini-fan to blow hot air down to the canister. That's starting to get complicated.

That was one idea why one guy used to use a really thick aluminum windscreen. His idea was that it would catch some heat from the flame at the top, and then conduct it down where it squeeze-fitted onto the canister. I don't have any big problem with that concept except that it sounds heavy. Plus, by its very nature, a big windscreen has a lot of surface area subject to the wind to get cooled.

You could use a hollow metal tube filled with a liquid that carries heat well, like liquid sodium. But that sounds heavy also.

It seems that the closer you get the metal wire to the hot flame the better.

–B.G.–

[Jeremy and Angela]

You could use a hollow metal tube filled with a liquid that carries heat well, like liquid sodium. But that sounds heavy also.

NaK might work better, as it's liquid at lower temperatures. Of either metal, I'm not sure the added weight would be my primary concern.

[Jerry Adams]

For me, the problem is solved. I don't camp much below 20 F.

Isobutane works down to 25 F – boil time will be 4 minutes rather than 3 minutes which is minor inconvenience

With the 0.33 ounce #14 copper wire 20 inches long, with N butane (?), it operates the same at 23 F as at 40 F without the wire. So, with isobutane and the #14 wire, I should be able to operate at 11 F.

I think I'll get a chance to test this Saturday or Sunday morning when it's supposed to be 10 or 15 F. Probably won't get that cold here again in a few years.

[Jerry Adams]

"Maybe transmitting the heat from the flame down to the canister is more important than conducting it into the canister"

I felt the wire right where it touched the canister and it wasn't hot.

If the effectiveness of this system was more affected by conduction between the wire and the canister, it would be warmer there.

Therefore, I don't think flattening the wire would make much difference.

If this system didn't work good enough, get a thicker gauge wire. #10 would weigh 0.85 ounces for 20 inches and has 2.5 times bigger cross section so it would transmit 2.5 time more heat (?)

But this isn't well thought out, need to experiment to verify

[Bob Gross]

Jerry, I don't think that our mammalian fingertips are very sensitive when trying to feel the difference of only a few degrees F when they are around freezing. In other words, I don't think that you will feel much difference when there is actually a little bit of difference there, and it is only that little bit of difference that we are after.

Besides, why do you need 20 inches of wire? You have the wire into the flame and then going down to the canister. I would think that you need only an inch or two of wire on each side of the joint in order to conduct that little bit of heat. Beyond that, you could use a lighter bit of strong wire, like very thin steel. Depending on the stove, you might be able to get rid of half of that wire length.

–B.G.–

[Billy Ray]

Maybe try some of that copper wire that goes to the thermocouple in a hot water heater?
Is that copper wire hollow?

Billy

[Bob Gross]

Billy, I believe that is solid copper wire.

A thermocouple generates a tiny voltage, and that is conducted electrically up to something like a solenoid/valve which opens and closes, thereby turning off something like a natural gas supply line to a burner.

–B.G.–

[Billy Ray]

Hmmm, I wonder about using the copper that comes with a thermocouple on the end of it… (I think it might even be hollow = lighter weight? better conductor of heat?)

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?

Also… why not wrap it around the top where the lip is near the valve?

whadaya think guys?

Billy

[Nick Gatel]

"whadaya think guys?"

Inverted canister stove or WG gas stove. We can end the debate and go hiking :)

[Billy Ray]

Nick..

this is not a debate; it's research!

Billy

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