small woodgas

[Jason Griffin]

Would it be possible or practical (burn time) to make a small enough woodgas stove to nest inside a trappers mug or firelite 550?

[Christopher Williams]

I own a BushBuddy, and can say that the burn time would be terrible. You would likely have to constantly feed something smaller. As it is, I need to feed my BB every 3-5 minutes, or it goes out.

I would think that something 1/2 the size would be too small. Besides, you would have to break the sticks down so small that they would burn up instantly it seems.

[Keith Selbo]

The firebox on my stove is a pint paint can. I have to stoke it about every 3 minutes. It doesn't bother me to do that.

Basically, when it stops smokin', it's time for stokin'. I find things to do that can be interrupted like sorting my gear, or filtering water from a dirty bag to a clean one.

[Michael Skwarczek]

I made a woodgas stove using this 12oz steel can and, essentially, a steel tmto paste can for the inner. Same essential design as a BB. I've made a few in a variety of sizes. This one just wasn't efficient. Not enough heat output, needed to be fed continually, and died out often. Looks nice, though.

[Dan Yeruski]

It's possible to make one.

Make a Garlington Stove stove from a vegetable can Read his instructions once and then throw them away.

We want to call his stove a top lit wood burner.(disregard all that other stuff he says about down draft gassifiing) That's all it is. Once lit, gasification starts taking place on it's own and proceeds to burn it's way down to the bottom of the can. It's clean burning if dry twigs are used and one load of compacted twigs will heat 2 cups of water to 200 degrees no problem.

When I find my photos and vodeo I'll post.

[Sam Haraldson]

> …Make a Garlington Stove stove from a vegetable can Read his instructions once and then throw them away.

Haha! "read them once and then throw them away." Good one, Zelph!

[Michael Skwarczek]

I'm going to re-investigate this. I was determined, previously, to use this woodgas stove with my heine pot. The goal was a stove to fit in the pot for packing. But with the tall, narrow design, I just couldn't bring it's 16oz to boil. Maybe with a SUL-550 I would have results similar to the 2oz of twigs reported by Zelph. I'll do some twig gathering tonight and check it out.

-michael

[Dan Yeruski]

>Haha! "read them once and then throw them away." Good one, Zelph!….

Dan smiles alot……

We have to take everyting we read with a grain of salt, take the better part of what we read and run with it. Try it, try it again and then if it works we ventured and we gained. No matter what happens, we gain experience.

The Garlington Stove works BUT, it's finicky as all get out. Needs to be watched carefull on start up. As long as the small twigs are packed close to gether it should burn all the way to the bottom with plenty of air holes feeding in from the bottom. If your twigs are dry, the stove will burn without much smoke at all. Buildong and test the stove was a good experience.

I have not been able to find my photos of the Garlington as of this writing =(

[Dan Yeruski]

Not able to load video, sorry folks. Let me see if i can get a link to it.

Alright see it this works Garlinton Wood Stove by Zelph

[darren stephens]

It was interesting to see the clock in the background. I think it would be more relevant if you started the clock before you collected the sticks..

[Dan Yeruski]

There are no clocks on hiking trails and off the trails.

You must be a canister user and don't have time to smell the flowers. Point A to point B do not deviate!!!!!!

Jason Griffin might be interested in the amount of time 1 load of wood burns in the small can.

[Keith Selbo]

"It was interesting to see the clock in the background. I think it would be more relevant if you started the clock before you collected the sticks.."

We pick up our sticks as we hike, but if you'd prefer not to make multiple use of your time, I've never had to go more than ten feet from the fire ring to find all the twigs I need to cook dinner. It takes a minute or two.

[Dan Yeruski]

If we go back and look at the diagram of the King of Woodburners, we see that initial air control is necessary for start-up and further burning.

Fuel burning too fast, reduce air flow.(fewer holes or smaller size.

See the last post in this thread

[Michael Skwarczek]

I have no time for testing or tinkering these days. I feel lazy here, but all I can do is ask questions.

Dan, have you tried a control valve such as a sleeve to change the size of the oxygen intakes in the outer sleeve?

Also, what do you think about the aluminum sleeve for providing heated air to the upper intakes? I'm pretty excited by the idea of replacing the built-in outer sleeve with this lightweight solution, if it's actually a helpful component. Frankly, I haven't really built or tested anything but the BB design. And I know you often espouse the virtues of a simplified stove design, minus the outer sleeve.

cheers,
-Michael

[David J. Sailer]

I designed a gassifier based on what Rick "Risk" Allnut and Ray Garlington have done, plus some other sources and experimentation. See http://www.imrisk.com/woodgas/ddstove.htm and http://www.garlington.biz/Ray/WoodGasStove/ for their work. The Zen Stoves site also has a bunch of info: http://zenstoves.net/LinksGeneral-DIY.htm#WoodBurningStoves

My design is at http://ultralighter.blogspot.com/2008/06/gassify-me.html

I don't use it much, preferring alcohol for convenience, but it works well. Burns extremely hot (like a blowtorch) for 10 to 12 minutes, tapering down to a warm glow. More than adequate for heating two cups of water for hot food, plus a cup or two more for coffee or tea if you can switch pots fast enough.

I deliberately used a small can to make it, which may be a problem if you have large (i.e., normal-sized) male hands. Weighs 3.8 ounces, and is all one piece. Steel too.

Plug: More info on a couple of books I've written and other stuff at http://ultralighter.blogspot.com/

[Dan Yeruski]

Michael, I have not tried to control the air in the outer sleeve. I really can't see how heating the air in the outer chamber is going to help combustion. The fire inside the inner container is blazing hot and doing quite well on it's own. It's burning hot as all get out. When the flames and gases reach the upper rim of the single can stove they mix just fine with air and combust like right now. My single wall stoves burn hot and heat 2 cups in 8 min or less. (Globe Stove, Veggie Strainer Stove, Martha Stixx stove, Hobo Elite stove and my Modified Zip single wall stove)
The modified Zip with one wall removed proved to be more efficient than the double wall.

Michael, remove the outer wall from your stove and do some test burns next week when you can make some time for some fun stove work.

I don't think the double wall is worth a hill of beans.

Nobody that pays the extreme price for a BB is going to admit there are any cons about the stove. Let's be realistic, a small veggie can stove can do just as well as a BB. The ones that have purchased the BB will do nothing but say good things about it because they paid the price, don't want to be known as a sucker. They got Stainless Steel for their money, just like the ones that buy Titanium goodies. Just some quality metal, that's all.

Nobody is going to prove to me that air traveling 4 inches up the outer wall is going to have an effect on the ignition of gasses coming out of the inner can. It's hype to sell a stove. My modified Zip stove tests proved to me that the double wall is insignificant in the performance of the stove.

High Performance car engines introduce cold air for better performance. Think on that for a while. It's not apples and apples, but something to think about.

Nobody questions my findings, why? Where are all the big guys that develope these third world country stoves? Why are they not sucessful in their sales to those under developed countries?

Cheers
Dan

[Nia Schmald]

I've been wondering about the double wall stoves since I first saw Zelph's zip stove test. Although I still went ahead and made one. They do look cool.

Any interest in a wood stove test BPL article? This could be similar to the one done on alcohol stoves a couple of years back.

[Derek Goffin]

Dan Alphabeta "Nobody is going to prove to me that air traveling 4 inches up the outer wall is going to have an effect on the ignition of gasses coming out of the inner can. It's hype to sell a stove. "

I can't prove to you that the outer jacket has any effect because I hav'nt tried my stove with and without its outer.
I accept that the double wall is not essential because the most I would expect would be a little more efficiency and a little less smoke. Neither of these make a lot of difference even if I could prove it.
However:
1) the air in the double wall is very hot as even the outer jacket is scorching hot. The outer stops this air being blown away and the chimney effect injects it into the top of the firebox in a way which looks more effective than the "secondary air by accident" effect which you mention.
2)If you mix the secondary air with the fumes well, rapidly, hotter and lower down you should give the flames more time to burn before they are quenched by the cold pot. I would have thought that whilst "When the flames and gases reach the upper rim of the single can stove they mix just fine with air and combust like right now" these flames have mostly escaped the pot stand before they start burning and are less likely to effectively heat the pot.
3) My aluminium outer only weighs about 10 grams and nests with the pot.

I agree about the engines wanting cold air but that is quite different they are after more molecules of oxygen per cylinder to get more performance. It is widely accepted that in stoves secondary air is better preheated. So you are out on a limb if you claim no effect at all. Engineers go to great trouble to mix the fuel and air quickly, turbulently and by injection in engines. I know that is a different situation from a stove but it fires the imagination.

[Dan Yeruski]

Hi Nia, I agree the little jets of air coming into the main burn chamber makes the stove look cool. (same with alcohol stoves that have little jets)

At the present time I have not considered doing an article on wood stoves. Maybe in the future.

You mentioned seeing my results of a test conducted on my Sierra Zip stove. I have provided a link to the thread on my web site so others can view the results of the test.

Roger, the results of my testing the Sierra Zip double walled stove against a Modified Sierra Zip (inner wall removed) is what puts me out on limb and makes me stand firm on my beleifs that the double wall is insignificant in the performance of the backpacking size stoves that we see being marketed(BushBuddy)and being made by DoitYourselfers.

I belive my tests were conducted in a fair manner. They were conducted on the same day aunder the same weather conditions. Please view Modified Sierra Zip Stove thread and see how I conducted the test and the information that I have made available.

My tests stand alone until someone else takes the time to conduct one similar. The above link will show how I went about cutting the inner wall out of the stove and the tools used.

Those of you that may have built double walled stoves may want to eliminate one of the walls to do a comparison test as I have with the Sierra Zip.

[Michael Skwarczek]

I'm going to commit myself to testing this weekend.

Twig resourcing is a pain in the heart of LA. Even in the nearest trail system, my pickings are scrub.

So, I used equally sections of knotty pine for testing at home. What would you recommend, for consistent results, that I could source for a hardware store. Doug Fir, Birch, and Pine are cheap. There's hardwoods too, but that seems a waste, not to mention expensive.

-Michael

[Dan Yeruski]

Michael, I used clothes pins and craft sticks(popsicle size and large tounge depressors. Easy to count out for each test burn. No need to weigh them, they are uniform in size. Dowel rods are also available but are more costly. At the larger lumber yard stores you can purchase packets of shim stock(tapered wedges) used when framing-in doors and windows. They also are of the same size usually, easy to control fuel amounts pretty darn close.

Good to hear you will be doing some comparative test burns.

Dan

[Keith Selbo]

A double wall offers some advantage, but mostly if you fill the space with insulation. That keeps the heat inside the stove from whence it moves to the pot.

There is a lot of academic research out there on small cook stoves. I think people would benefit from reading it and building on it rather than starting from scratch. Here's the conclusions I extracted from one paper:

If one were to draw up a preliminary list of “steps” that one could take to get good heat
transfer efficiency, it would look something like the following.
1. Match the size of the fire to the size of the cooking task. A 3 kW fire at 50%
efficiency delivers the same power to the pot as a 5 kW fire at 30% efficiency,
while burning only 60% as much fuel. It is easier to get high efficiency out of a
small fire than a large one.
2. Choke off the excess air as much as possible without sooting.
3. Do not allow the hot gases to rise in an unconfined plume (like an open fire). (this pretty much puts the BushBuddy out of the running)
Cool air is entrained into the rising plume of hot gas, cooling it and reducing the
potential for heat transfer.
4. If possible, use a confined passage under the pot, and a skirt. Use a large pot if
possible. Tight skirts, narrow flow passages, and tapered flow passages that keep
the flow area constant appear to not be worthwhile.
5. For the simmering phase, use as small a fire as possible, and a lid on the pot.
Note that the amount of power required to keep a pot simmering with a lid is very
small, hence it is likely that the fuel consumption during the simmering phase will
depend more on how small a fire can be used and maintained, preferably without
operator intervention, than it will on the heat transfer efficiency. In other words,
such a stove will have low specific fuel consumption, even though it may not
have a high percentage of heat utilized.

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