stove for winter

Hi Gary

Since you are in a tent, there shouldn’t be appreciable wind.

Theory and experiment may differ. Yes, we can get some mild wind inside a tent at times. That depends on what the wind speed outside is like. :-)  But normally you are right.

An important part of our day is morning tea and coffee. That’s out in the open. I still use the same windshield set up the same way for that. So I am not dependent on a still environment by any means. If it is quite windy I sometimes use a couple of micro-stakes to hold the windshield down.

When you use the term wind deflector, does that mean that you are primarily employing the wind screen to deflect heat back to the pot (and also to the canister)?

No. I use the windshield to deflect wind away from the flame, to shield the flame from the wind, so the flame hits the pot as it is meant to. That is pretty much it.

To be honest, I don’t think I have ever thought of a wind shield as being something to deflect heat towards anything. I guess it does a bit, but it only contributes maybe 1% of the energy you get from direct flame hitting the pot.

On the other hand, i have used a disk deflector around the neck of a stove to deflect radiation away from the canister. But these days I don’t bother with that either; the pot heats fast enough and I just keep an eye (or a finger) on the temperature of the canister.

All pretty simple.

Cheers

It does seem like this is all pretty simple, but I am always wondering if there’s something that I might be missing. That’s why I am asking so many questions. Thanks for indulging me, Roger.

For my part, I like to have a complete windscreen around my pots when I can, and I prefer titanium ones because of its poor conductivity. I believe this keeps more of the stove’s heat in contact with the pot, which is my goal.

So tonight I will place the stoves on the patio table before I go to bed. The overnight low temperature looks to be about +5-6* F, and a good chance to do one more test before global warming resumes.

I think the windscreen is just to keep wind from disrupting the flow of heat from the burner to the pot.

Without a windscreen even in light breeze, you can see the flame getting blown all over.  And it takes twice as long so you’re using twice as much fuel.  If it’s windier it will blow the flame out.

It doesn’t matter if there’s a gap on the lee side.

Ti is a little lighter but not much.  Ti is definitely a good marketing feature.

I’m too lazy to test this : )

“global warming resumes” – good one : )

“For my part, I like to have a complete windscreen around my pots when I can, and I prefer titanium ones because of its poor conductivity. I believe this keeps more of the stove’s heat in contact with the pot, which is my goal.”

If the windscreens are directly touching the pot all around, the difference in conductivity between titanium and aluminum might make a very slight difference, but if there is an air gap, even a quarter of an inch, i doubt the conductivity of the respective metals will matter much at all.  If anything, the higher reflectivity of aluminum might be a slight advantage.

I’m currently working on a set up inspired a bit by Matt’s earlier reply on the heat exchanger pots.  A tall windscreen made out of aluminum flashing, which goes up a little over 1/3 of the pot, and directly over that and the pot will be a heat resistant, insulated “cozy”, made out of aluminum flashing, with green fiber insulation within (we have some left over from a shed project).  The idea is that the windscreen will direct the lost heat up into the cozy, and the insulated cozy will keep it in and transferring to the pot while it’s cooking, as well as insulate it after it’s done.  For extreme cold temps.

Might be a waste of weight and volume–tbd.

Having a wind screen in direct contact with the pot won’t work at all, as you need a space for the exhaust to rise up and escape (usually a .25-.5 inch space). Taller is better, as it contains the heat longer and these gases help heat the sides of the pot as they rise. I expect that a 3/4 screen wouldn’t be as efficient as one that fully encloses the pot. Too much heat would be lost through the large opening. It will certainly prevent the main wind flow from messing with the stove’s flame, but you won’t be able to keep the excess heat near enough to the pot. The more heat you get to the pot, the better.

This is where access to the stove’s valve is important when using a fully enclosed wind screen, as we must be sure that the flame is adjusted so that the fuel is completely burned. If the wind screen is too close to the pot (say < .25″ space), the chimney effect is lessened (the exhaust gases struggle to escape upward), which will affect the combustion of the fuel at the burner head. Reducing the flame helps with this, and allows the fuel at the burner to not be starved for oxygen.

I look forward to seeing what you come up with, Justin. Your idea sounds interesting.

Fwiiw, the following is how I see it.

With an alky stove you are getting a low amount of low-grade heat. In other words, the flow of hot gas is not all that big. But the flames can be quite long: we have all seen photos of them licking up the sides of a beer can. So you need to make sure that the flame and the hot gas is as close to the pot as possible, to get the maximum heat transfer. That leads to the all-enveloping pot support / windshields we see in the alky world.

With a canister stove things are a bit different. The power of such a stove is much higher, and that means it is generating a lot more very hot air. The flames are usually much shorter as well 9or they should be), so the heat is generated much loser to the burner head. To be sure, for best efficiency you want to get as much of that heat into your pot as possible, BUT you have to cope with two other requirements as well.

First of all, you have to let the hot gases escape, because a whole lot more are coming off the flame and have to go somewhere. You simply cannot afford to bottle the hot air up the way you do with an alky. At the worst you may overheat your canister, or at least the stove and the crucial O-rings inside it.

Second, if you inhibit the outwards air flow much, you will also be inhibiting the inwards air flow, and that leads to serious problems with CO generation. If you want low CO levels, you must allow a good flow of air into the flame.

You don’t want the wind blowing the flames away from the pot of course, but even a 1/2 wrap windshield can block that. You do need to keep the rim of the windshield at least 10 mm and more like 20 mm away from the pot, to get the decent flow of air through. And only having the windshield 3/4 of the way around the pot does not alter any of that, but it does make sure the stove is getting as much fresh air in as it needs.

Frankly, the sight of full-wrap windshields around any canister stove worries me, even with remote canister stoves. You have a high risk in those cases of melting the O-rings.

Cheers

Agreed on all you said Gary.

I can see your points Roger, but i figure experimentation might show some interesting results.  My stove is a remote canister one, and i wrapped the hose connection and part of the hose with self adhesive silicone tape.  Should help to insulate it from the extra heat that will be generated with a more enclosed design.

I’m not worried about CO since i almost cook either out in the open or in a very well ventilated area.

But it does sound like maybe i should modify it, to have the windscreen on the outside of the cozy so there is a little more ventilation and hot to cool air exchange.

Hi Justin

If silicone tape was all that good an insulator, we would would not be using down in our quilts. Just remember, the flame temperature can be >1,000 C.

And the tape around the hose won’t protect the O-rings in the stove body. If an o-ring fails …

Cheers

I’m new to canister stoves (clearly).  Sounds like i should keep this for alcohol only.

Bwaah haaah haaah

Another poor soul subverted to the dark side of stoves …

Your soul is mine…

Well, now that you own my soul, you are responsible for general upkeep and maintenance….

But yes, i have seen the light in relation to canister stoves.

Well, now that you own my soul, you are responsible for general upkeep and maintenance….

Hum, well, that’s a burden I had not anticipated.
Delegate, delegate …

Cheers

With all this talk of gas vs liquid stoves for cold weather, I really just have one question, and it will probably sound stupid.  Why not solid fuel?  Folks have mentioned Esbit for emergency or for fire-starting, but why not a titanium tripod Esbit stove, with a bunch of tabs as your cooking/ melting system?  Would it simply require too many fuel tabs?  I know it leaves a nasty film on the bottom of my pot, but I can see at least a few advantages:

First advantage is the weight and simplicity of the stove itself.  You simply can’t get lighter or less finicky.  Next comes the fact that your fuel weight is going to be drastically dropping during the course of your trip.  There is no flammable liquid to accidently spill in your pack, and no canisters to sleep with.

So the downside I can see would be that they seem to take a long time to heat anything up.  On the surface it seems like such a simple solution…there must be something horribly wrong with them that I’m missing, or everyone would be doing it.  What am I overlooking?

The only thing I know is that canister stoves for cold weather are not an option for me.  I had a very negative experience with them and won’t be trying that again.  For me it will be solid or liquid from here on out.

Hi Doug

Why not ESBIT? Well, give it a try in the snow and see how it goes. Desperately underpowered, slow and messy would be the short answer.

canisters .. I had a very negative experience with them and won’t be trying that again.  For me it will be solid or liquid from here on out.

Chuckle. Canister stoves are a liquid fuel, just like white gas. They are all long-chain hydrocarbon fuels. Read some of our stove articles here at BPL for more information and education.

Cheers

A few problems that come immediately to mind;

Energy denisty — I don’t even know the numbers, but the amount of fuel needed to heat water is a practical guide, and it takes about 10-14g of Esbit to heat 500ml of water, while canister gas uses about 5g of fuel. Melting snow to obtain all water will require about 3x the normal amount of fuel for 3-season, so those numbers add up quickly against Esbit (and alcohol as well), both in weight and in bulk.

Heating speed — Canister (propane/isobutane) can bring to a boil 2 cups of cold water in about 2 minutes while Esbit might take 6 minutes or more. Melting snow for all water needs? You’d need a calendar to time it. :^)

Cost — About the cheapest price I have found for Esbit is around $5.00 for 12x 14g tabs. As above, just to be conservative it’s best to use the 14g per 500ml number (because in winter, even if running water can be found, it’ll be cold), which is 28g per day for fuel typically, compared with 10g per day for the canister. Melting snow for water would translate to 84g per day with Esbit (6 tabs at the very least) vs 30g per day for canister. Fuel cost for Esbit would be about $2.50 per day and canister about $1.65.

So within a couple of days the weight of the canister becomes a moot point, and very soon it comes out ahead in the weight department.

There are a lot more variables in play, but that’s my condensed version or why it isn’t practical for me.

edit: posting same time as Roger… Yep, if you don’t believe any of this, just get some Esbit and go on a short overnight winter trip and give it a field test. Not too far into the woods if you’re craving a hot dinner. It will provide a stark lesson about Esbit shortcomings (BTW I love Esbit for late spring, summer, early fall). But swearing off canisters after a bad experience is like swearing off automobiles after an accident. Learn from it and move on, IMO. They can work just fine in winter.

Probably mentioned it on this thread already (if not on another) but remote canister stoves work very well in winter, I use them often in sub 0F (coldest -13f) and never had an issue.

“Chuckle. Canister stoves are a liquid fuel, just like white gas. They are all long-chain hydrocarbon fuels. Read some of our stove articles here at BPL for more information and education.”

Roger, I apologize for using the wrong terminology, but you’re arguing semantics.   I’m sure you knew what I was referring to.  Your short answer was helpful, and I wish you’d left it at that.

Bob, thanks very much for your response.  I guessed that this was the reason, but having never used Esbits for melting snow, or in winter, I wanted confirmation.  I haven’t sworn off canisters for backpacking, for summer use I love my little snowpeak gigapower.  In my limited winter camping experience they were horrible, and I’m not interested in strapping a metal bar to the outside of the canister with Velcro.  I’ll stick with my white gas stove for winter it looks like.

Hi Doug

Semantics? Yes and no. Some people were of the belief that propane/butane and white gas were seriously different fuels (like comparing alcohol with white gas), so I have been emphasising that they are not.

Fwiiw, I agree with you that conventional uprights do not work well at or below freezing. That’s why I have been developing remote canister winter stoves.

Enjoy!

In my limited winter camping experience they were horrible, and I’m not interested in strapping a metal bar to the outside of the canister with Velcro.

So you’re not interested in something that completely solves your problem for a weight penalty of 1 oz, is cheap, is safe, and works with your favorite stove.

Can’t argue with that logic.

I really couldn’t care less one way or the other because I have absolutely zero profit motive, but your rationale escapes me.

Fwiiw, I agree with you that conventional uprights do not work well at or below freezing.

Without any effort to warm the canister? I agree.

But with a simple heat shunt it is a whole other story. Pictured below is my JB MiniMo (with a 1.8l Sumo cup) putting out as much heat at +4°F (-15.5°C) in the Catskills as it would on a beach in Jamaica, with no pre-warming of any kind. And it started up the next morning with no canister pre-warming after sitting out all night, although by morning the temperature had warmed up to +12°F (-11°C). I melted snow to produce about 4 liters of water on this particular burn and there was no drop-off in performance in either the evening session or the morning session. My tests repeatedly demonstrated excellent stove performance to the last molecule of fuel, and Gary Dunckel has gotten the exact same results from his tests in Boulder.

With the heat shunt I suppose it is no longer “conventional”?

Hi Bob

With the heat shunt I suppose it is no longer “conventional”?

Well,  people have been putting heat shunts on the side of the canister for decades now. Originally it was some solid copper wire wrapped around the canister; only later on (afaik) did the use of a strip of copper or aluminium come in. I don’t know where it started, although climbers/mountaineers are supposed to have been some early users of the idea.

It was always regarded as a bit unconventional, or even risky, at least by the lawyers for the stove and canister companies. Other users weren’t interested in going outside when it was below freezing?

And it started up the next morning with no canister pre-warming after sitting out all night, although by morning the temperature had warmed up to +12°F (-11°C).

You would have been running mainly on the propane in that Primus canister for a minute or two, until the heat started to flow down the strip. But that’s OK, as long as you remember that there won’t be nearly as much propane in the mix when you get down to 1/4 full.

Cheers

Well,  people have been putting heat shunts on the side of the canister for decades now. Originally it was some solid copper wire wrapped around the canister;

Yes, I have known of this for a long time, and even included a photo to illustrate the typical ramshackle arrangement. Looks dangerous and ineffective and I wouldn’t use that either. I think my solution with the copper strip, velcro strap and silicone insulator answers all those concerns.

It was always regarded as a bit unconventional, or even risky, at least by the lawyers for the stove and canister companies. Other users weren’t interested in going outside when it was below freezing?

Oh yeah, I wouldn’t be surprised in the least to get a cease-and-desist letter from somebody, even though I’m not selling them. As to safety, as I mentioned elsewhere I put myself in the shoes of a complete moron and ran the stove in ambient temperatures up to 80°F with the HX strip in place, canister in the foam cozy, stove running full blast for 1/2 hour, and I’m still here to tell the tale.

Regarded as a bit unconventional? Name something that wasn’t at some point. :^)

People not going outside when it’s cold? Not my crowd, for sure.

You would have been running mainly on the propane in that Primus canister for a minute or two, until the heat started to flow down the strip. But that’s OK, as long as you remember that there won’t be nearly as much propane in the mix when you get down to 1/4 full.

In reality, it takes an exceedingly tiny amount of propane to get the feedback loop going. During my tests in my lab (the back deck) and in the field I have run many canisters (a lot of them nearly empty) completely out of fuel at very cold temperatures, which suggests to me that once the feedback loop is going and a cozy is used to retain heat, it might well run fine with zero propane. Theoretically, my upcoming tests with pure n-butane should be a total flop, but I am not discouraged from at least trying… theory and reality quite often disagree.

“So you’re not interested in something that completely solves your problem for a weight penalty of 1 oz, is cheap, is safe, and works with your favorite stove.

Can’t argue with that logic.”

Bob, if you’re comfortable doing it, great!  I’m glad it’s working out for you and others.  I admit, my thought process is based more on emotion than logic, but I have an aversion to performing modifications to anything dealing with open flames and canisters of gas.  When you think of it in those simplest of terms, hopefully you can see where I’m coming from, even if you disagree.

Doug, I certainly see where you’re coming from, and I had some hesitation myself for that reason.

But, ultimately, I think it’s a quantitative risk decision, not a qualitative one.  Many (if not most) BPL strategies involve less robust equipment, and compensating for greater risk of breakage with skill and experience.  So there are plenty of non-stove elements of typical lightweight kit that could also get us into serious trouble in the backcountry (especially in winter) without skill and experience.

I was convinced by the thoroughness with which Bob and others have done the riskiest part, the R&D, and been generous enough to pass on their skills and experience, so that I’m won’t feel like I’m hacking around like a total noob.   Similarly with Roger’s stoves – I doubt that any commercial manufacturer has done more extensive R&D and testing.

Doug, there’s no blame at all for you taking the conservative approach. Bob has chosen to think outside the box here, and in my opinion he has come up with a true winner. This system really works, and at just a one ounce penalty. I have modified his concept slightly, and I’m thrilled with the results. The stove(s) run happily at temperatures down to +5* F by employing this technique. I don’t know how low you can go, as it hasn’t gotten colder than that this winter–at least not here at home, not yet. The mountains have seen below zero temps, but I don’t prefer to expose myself to those conditions much anymore.

Bob has reinforced my feeling about the collective spirit of BPL, where he has shared a concept with us all, without any motive for profit. People can take it or leave it, but it shouldn’t be dismissed as folly until it is tried out for oneself. I consider Bob’s offering as a type of PIF to us.