What's the difference between a woodgas stove and a hobo stove

What's the difference between a woodgas stove and a hobo stove - Stove Mods theory lesson

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9 жыл бұрын

What's the difference between a woodgas stove and a hobo stove - Stove Mods theory lesson
Some people wonder what the difference between a hobo stove and a woodgas stove is.
I will answer and explain this question using some graphics showing a cross section of a woodgas stove.
A woodgas stove can be shaped very similar to a hobo stove but it uses a second system to transport more air/oxygen into the burning chamber and create a more efficient fire.
Unlike a hobo stove the woodgas stove needs two walls. Once the walls become heated up by the fire inside the stove the air between the walls will expand due to the heat and move upwards. At the upper end of the inner wall are holes that allow the hot air to leave the space between the two walls and enter the burning chamber. There the extra air causes a secondary burn and helps burn gas that otherwise just would have left the stove without being used. Thus the stove burns very efficiently!
A diy hobo stove or diy woodgas stove is a great solution for outdoor cooking or camping.
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Пікірлер: 84

@dineshjoshi4100 3 жыл бұрын

Thanks for explaining it in such a understandable way. Much appreciated.

@stovemods8231 3 жыл бұрын

Thank you :-)

@Seamus3051 5 жыл бұрын

Excellent tutorial; thanks for your clear and concise explanation ... Cheers.

@stovemods8231 5 жыл бұрын

Thank you very much :-)

@briannugent5518 3 жыл бұрын

For anyone still seeing this video. It should be mentioned that some wood gas is drawn downward thru the bottom holes of the inner burn pot and mixes with the incoming air providing a hot fuel air mixture at the jets, not just hot air. If the air supply comes from a small computer fan with a select-able power, then the flame size can be varied in strength though it remains orange and sooty and the bottom hole arrangement is poor for a fan assist. Instead 1) place the bottom holes as a ring around the bottom of the inner burn pot sides such that the combined area of all the bottom holes is about 1/3 the combined area of all top holes and the ring should be about 1 or 2 cm from the bottom of the burn pot at the level of the coals. 2) direct the fan to blow thru a single large opening in the bottom of the outer can such that it flows up the annular gap for a few cm before passing over the bottom ring of holes to suck up wood gas from the pyrolysing fuel. Little baffles could add turbulence for better mixing. 3) now varying the fan will mix the wood gas so the jet flames range from lazy orange colour jets with black sooty tips all the way up to very turbulent bright whitish yellow flame jets with blue hints and at the base of each flame jet. The latter is super clean and consumes the fuel much faster. Dr Tom Reed pioneered gasifier stoves decades ago so just search "reed inverted downdraft gasifier stove" for best designs, and detailed gasifier theory. Using a fan makes these inverted downdraft wood gasifier stoves operate with positive pressure but you can also set such a stove (with out a PC fan) inside a large thick steel metal box which has a controllable extractor fan for the chimney thus operating the stove on negative pressure. The flames looks the same in either mode.

@stovemods8231 3 жыл бұрын

Thank you for your datailed Input! There are always things left to learn :-)

@joebourgoin6554 10 ай бұрын

Do you have any videos of these designs? Sounds super cool

@briannugent5518 10 ай бұрын

@@joebourgoin6554 Sorry no, I have experimented with these stoves for personal knowledge then dismantled everything. Search for designs based on Tom Reed stoves and add a PC fan with variable control. Other experimenters have made videos. The flames are hotter, has more bright yellow hue than orange, is more turbulent because of good air mixing, there is much less soot / unburnt smoke (wood gas). Search wood gasification for more general results.

@greenwood4020 8 жыл бұрын

Great Great diagrams and explanations of the air flow. So many get these basics wrong On the question of BOTTOM UP or TLUD 1 - If your only using it for a small amount of heat ( eg. to boil 1 cup water) the bottom up method works fast and you can add just enough fuel as required to complete the coking/boiling process and you have very little waste/unburnt fuel at the end 2 - But if doing some serious cooking then the TLUD (Top Lit Up Draft) method gives a longer more controlled burn and you don't have to hang around feeding the fire, lifting on and off a big pot of boiling water/food to add more fuel TLUD = Top Lit Up Draft the fire burns longer and more efficiently if wood is packed in and lit from the top like it is designed to be used. The fire then only heats and gasifies the wood near it and heats the sides of the internal metal cylinder causing the vents to let out warmed air to ignite the rising wood gas. This gives an even and controlled longer burning process from a bigger initial batch of fuel. If BOTTOM LIT, the fire heats ALL the wood ABOVE IT rapidly gasifying it often giving off more gas than the air vents can cope with. This results in lost/unburnt wood gas= blacker bot bottoms = lost potential heat = short lived fire = less efficient fuel use If you mainly use bottom lit, then the secondary air holes need to be bigger or more numerous It just depends what your cooking each time, which method you choose to use standing on the shoulders of others

@stovemods8231 8 жыл бұрын

+Greenwood Thanks a lot! This is a very good explanation in my opinion. Having bigger secondary air holes for burning more wood at once sounds pretty smart as well. That confirms what I saw when I made the holes for one of my stoves bigger. The boiling time improved and in fact I lit it from the bottom in that case. Thanks again!

@reptilespit4433 3 жыл бұрын

Somple and excellent, now I can show off my Wood Gas Stove to my mates with logic 😅

@stovemods8231 3 жыл бұрын

I'm glad I could help ;-)

@wlacalle 6 жыл бұрын

Great example 👍 Thanks

@stovemods8231 6 жыл бұрын

Thank you very much!

@user-vb5fs1sf2y 8 жыл бұрын

A great explanation, the drawings make things really clear. Thanks

@stovemods8231 7 жыл бұрын

Thank you:-)

@gregscountrycabinoutdoors7359 8 жыл бұрын

Very few people understand the concept of the woodgas stove. Thank you for getting it right. Very good explanation of how it works. I have seen too many video's telling us that there is an inversion that causes the fire to burn down. that is BS. you nailed it.

@stovemods8231 8 жыл бұрын

+Gregory Bergschneider Thank you! In fact I have been told twice recently that I am supposed to start the fire in a woodgas stove from the top and let it burn down. I did not test it jet but there is also a recognizable effect with my woodgas stoves if I light them the usual way!

@TimpBizkit 7 жыл бұрын

When my powered fan woodgas stove burned out I did notice some smoke pouring out the secondary burn holes. It's possible that a bit of the smoke from the fire got sucked through the smaller holes at the bottom by the air moving through the walls but I don't think it was meant to be an inverted downdraft gasifier, although you can get them. Unfortunately I didn't look after it that well so it got old and rusty and it had also been repaired due to an internal fire I had burning some old cooking oil when I was a stupid kid. I used to put more volts to the fan and also it would burn coal and probably saw more heat than it was supposed to and got wet.

@Waldlaeufer70 7 жыл бұрын

You can easily burn a wood gas stove from top to bottom. However, the air does not move down, no matter how you use them. The hottest part of the stove is the compustion chamber. So, there is the strongest draught upwards. In fact, the flames of the secondary burn don't come out of the upper holes, they rather develop where the wood gas and the hot air meet just along the edge of the holes.

@lylemyers5931 7 жыл бұрын

Waldläufer70 n

@marcoilsanto 3 жыл бұрын

Hi, I recently discovered this pyrolysis phenomenon and in fact it has become my hobby of the moment. There are some things that are not clear to me, however. Strangely enough, the first tutorial I saw was with only one can, and in fact so I built my first stove. When the pyrolysis stops, a lot of smoke comes out. Then I saw that most stoves are made with 2 cans, and so did I. In addition to seeing the flames that come out of the holes above, when it ends, not all that smoke comes out. In this drawing you explain very well how the flows of air and gas occur. Can you also explain how they happen in one can?

@stovemods8231 3 жыл бұрын

Wow, this is a very specific question and I hope I can answer everything correctly. From what I understand pyrolysis is a thermo chemical process that happens without oxygen and therefore - from what I understand - is not happening in any oven. This is certainly a lot simplyfied but when wood burns the heat turns the wood into gas/smoke which reacts with the oxigen after being ignited and then creates heat which turns the wood into gas/smoke and so on. The usual reason why smokle occurs during such a scenario is the lack of oxigen so the gas/smoke can not react/burn. All the two cans do is transport additional oxigen to the upper end of a stove and inject it there into the burning chamber. Therefore the jets you see are driven by air/oxigen and not smoke and the gas that just would have left the stove without burning receives oxigen to burn. Therefore the double can uses the gas more effectively and clean. Now with one can the whole thing is a lot simpler. You have your firebed and wood in the lower part of the stove. The gas/smoke burns but only up to the point where no oxygen is left over (the upper end). The flow in the can goes just straight upwards. From the holes where the air is pulled into the stove through the burning chamber and out again at the top, pretty much like a chimney. This is the reason why when having just one can (which I personally prefer a whole lot) my advice always is to drill some additional air holes at mid height of the burning chamber. This adds some air as well but it is not injected with pressure into the chamber. Did this help?

@lalystar4230 6 жыл бұрын

what if you make a feeding hole on the side (low, like a rocketstove) and then sealed it closed in both the innerwall and the outer wall, so air won't leak at those points? You could even limit the amount of air intake through that hole by making a lid for it?

@stovemods8231 6 жыл бұрын

Sounds interesting but I am not quite sure if I can du that with my rather limited technical options. Have to think about this!

@CrlMchd 8 жыл бұрын

Greetings and congratulations from Argentina!

@stovemods8231 8 жыл бұрын

+Carlos Machado Thank you! Greetings to you as well:-)

@timwarneka5681 2 жыл бұрын

Thank you sir! Very clear explanations and drawings. A question regarding the 'top part' you discuss at around 2:40: does this top part have to be a solid piece of metal with an opening? Or can it be something perforated, like wire mesh? I've seen different opinions. Thanks in advance!

@stovemods8231 2 жыл бұрын

I would rather suggest something more solid because it is supposed to support the weight of the pot. Like an upward extension of the stove with holes. Also something like I used in this video on top of the stove might work in my opinion: kzfaq.info/get/bejne/qtOFdM-n2tjPm6c.html

@elmerdonasco4603 7 жыл бұрын

Nicely explain and very easy to understand. Thank you

@stovemods8231 7 жыл бұрын

Thank you!

@gustavgnoettgen 3 жыл бұрын

The gasifier stove can easily produce high power, but it's not so easy to let it burn with low power for a long time (until you have a good coal fire going). But it's possible. You need the best dense fuel you can get and you will need to build up experience with the stove and the fuel. The best you can find almost everywhere are thumb thick branches, just too thick to break them by hand. I highly recommend bringing branch shears. Cut them 1-2 thumbs short, that way they should burn for about an hour long evenly. But starting the fire is always different, it can be too fast easily.

@stovemods8231 3 жыл бұрын

Thank you for the detailed explanation :-)

@itsrickeritsricker 8 жыл бұрын

thanks for a good explanation time 2 play now :)

@stovemods8231 8 жыл бұрын

+Leon You are very welcome:-) What are you planning to build now?

@itsrickeritsricker 8 жыл бұрын

A bean can concoction lol

@stovemods8231 8 жыл бұрын

+Leon Sounds good:-)

@user-lz9de8nn7n 3 жыл бұрын

Thanks sir

@manasseskamau5327 11 ай бұрын

For the first time I have understood the theory behind the design.

@stovemods8231 10 ай бұрын

Thank you, I am happy to hear that :-)

@guillermoariast 4 жыл бұрын

Te best explanation I found

@stovemods8231 4 жыл бұрын

Thank you :-)

@nathansharp3193 5 жыл бұрын

Awesome! Just what I was looking for. I’m going to try using aluminum foil wrapped around my Ikea hobo stove and see if I can make it burn cleaner. I’m going to use (real) duct tape and aluminum foil to close off most of the holes going up the sides of the Ikea silverware holder. Then wrap another piece of foil loosely over the whole thing to create the outer wall/hot gas chamber. I already have the whole thing sitting up getting good airflow underneath. I think it will work according to your nice drawings. We’ll see if my execution works. If it does, I’ll post a video of it in action.

@stovemods8231 5 жыл бұрын

Please, if this works and you make a video send me the link! I am curious about it :-)

@nathansharp3193 5 жыл бұрын

Stove Mods : I did it! I made a video too, but haven’t uploaded it yet. I wrapped a piece of aluminum foil folded over in thirds around the middle holes of the sides of the tall Ikea hobo stove. I then made a ‘gasket’ out of some crinkled foil and wrapped a ring around the top rim. I have a fairly rigid piece of aluminum that I use as a windscreen that goes about 2/3 of the way around the hobo stove. I used that rigid aluminum as the outer wall and closed the rest off with more aluminum foil wrapped around the whole thing. Everything was secured using real duct tape - the aluminum adhesive type. It worked! I really don’t know if it was any better than just using the plain stove but it did make some nice jets of flame come out of the upper holes. The nicest thing about it was as it burned down and stopped producing the jet flames it burned very clean, almost totally blue and used very little fuel. It didn’t radiate heat to the sides so it’s definitely not as good of a ‘space heater’ as the simple hobo stove, nor is it as fun to watch burn because you pretty much have to look down into it to see much. This was just a proof of concept and I could smell the tape adhesive burning. I didn’t burn it very long, but nothing failed horribly in the 20 minutes or so that I was testing it out. It was dark so the video shows the flames well, but not much else. I’ll do some daytime video tomorrow. Hopefully I can edit it all together and get a decent video made. I’ll keep you updated.

@stovemods8231 5 жыл бұрын

@@nathansharp3193 Congrats :-) Seeing jets come out the upper holes and blue flames sounds like it worked quite well to me. I am really forward to see your construction :-)

@wangfeng175 2 жыл бұрын

very clear.

@stovemods8231 2 жыл бұрын

Thank you 🙂

@PaulOutdoors 7 жыл бұрын

A great explanation. Thank you. I always top light my wood gas stove having gauged the amount of fuel I need for a particular boiling or cooking task. I can add fuel if needed but it is rarely necessary depending on density of fuel, conditions etc. Thank you for sharing. Paul :)

@stovemods8231 7 жыл бұрын

Sorry, I obviousely overlooked your comment for months. Thank you a lot! I definitely need to learn more about lighting this type of stoves from the top!

@kisuke6517 2 жыл бұрын

what if i will put a controlled fan in the wood gas stove does it fuction the same

@stovemods8231 2 жыл бұрын

I never tried that but I guess that depends very much on the details of the build. Flow resistance and other factors might come into play even more. Apart from that I am not sure if it is that useful. From what I understand the woodgas stove is optimized for functioning the way it does. Adding a fan is a whole different ballgeme and might make the way a woodgas stove is built obsolete.

@frepi 7 жыл бұрын

I am sorry but this is not a complete explanation of the workings of a wood gas stove. The composition of the gases coming up in the double wall space is not strictly air but also gases expelled by the burning wood. If you take measurements of the pressure just below the holes at the bottom of the combustion chamber, you will see that the pressure is higher than in the double wall chamber. The burning wood expels gases and a big part of these gases are moving DOWN through the holes at the bottom of the combustion chamber then they are drawn in the double wall and exit at the top and ignite. The whole process is clear when looking at a wood gas stove with the outer walls made of glass. Ref: /watch?v=wzN-cYR84_Y&t=143s

@stovemods8231 7 жыл бұрын

Hi, thanks fo you comment! I think, everything you say is correct, just more precise than what I explained! By the way, somehow I can not use the link you put in the comment.

@adventurousandrew4442 6 жыл бұрын

frepi yeah, you are absolutely right.. he misunderstood the princip..

@kisuke6517 2 жыл бұрын

which is more efficient/consume less fire wood with more time

@stovemods8231 2 жыл бұрын

I have to admit I am not quite sure. My preference in use are clrarly standard hobo stoves. But I think I heard that some people use wood pellets for a very slow and efficient fire in a woodgas stove.

@lukaszoles 7 жыл бұрын

Unfortunately the description is wrong. It's wood gas stove and there is no word about "the gas". The only correct way to use it is to burn down. You fill the stove and fire it on top. Then gasification process is happening. This is why you need the secondary air chamber. It's very well described on wikipedia: en.wikipedia.org/wiki/Wood_gas#Stoves.2C_cooking_and_furnaces

@stovemods8231 7 жыл бұрын

Hi, thank you for your comment. In my experience the double wall also has a huge effect If you do not light the stove from the top, compared to stoves that do not have a second wall. Still, I know I need to be experimenting more with fueling them from the top! But I am very sure, the general principle I am describing takes place like that. But It might be true that I do not distinguish enough between air and other gas in this vid. You can always be more precise in life:-)

@lukaszoles 7 жыл бұрын

yeah, I agree that in general it helps. The think is that if you fire it from the bottom You cannot call it wood gas stove. That's all:)

@Radoslaw731 Жыл бұрын

I prefer wood gas stove because of the proven reasons you talked about and you can burn not only wood but wood pellets that are perfect fuel for these stoves, use sny type of alcohol stoves in them and the wood gas stove work as a windshield. You can use the base of the wood stove for windshield for gas stove, . In wood gas stove you can use charcoal, pinecones etc. It is really a multi fuel

@stovemods8231 Жыл бұрын

I am happy to hear it works so well for you :-)

@RAMKUMAR-mb3hc 6 жыл бұрын

Are the TLUD stoves same as wood gas stoves

@chriswass1176 6 жыл бұрын

I have the same exact question. Does it?

@stovemods8231 6 жыл бұрын

I do think they are from what I see on pictures but I do not own one and therefore can not tell for sure

@stovemods8231 6 жыл бұрын

I do think they are from what I see on pictures but I do not own one and therefore can not tell for sure

@RAMKUMAR-mb3hc 6 жыл бұрын

Stove Mods okay 😀

@DrHowbeit 4 ай бұрын

Does the woodgas stove produce less smoke? If so, what is the science?

@stovemods8231 4 ай бұрын

It is supposed to produce less smoke. The science is explained in the video ;-)

@maginalconquispe7191 Жыл бұрын

Se necesita probar. Sino es solo palabras.

@1979Spica 3 жыл бұрын

It also forces cooler, unburned gases downward. Then they mix with the fresh air and get superheated. That is why jets come out. Hot air itself will not create jets of flame. There is a better video that proves this with a outer chamber made of glass. He shows how everything flows with smoke. Much better learning tool.

@beboba2498 Жыл бұрын

It does not explain why we see flames coming from those top row of holes.

@stovemods8231 Жыл бұрын

The air in the wall moves upwards because it is hot. Eventually it enters the burning chamber through the top row of holes and reacts with fumes that have not been burned yet. This is what creates the flames.

@beboba2498 Жыл бұрын

@@stovemods8231 If you take a pipe, and push hot/cold air through it at any spot in your fire pit, you won't see any flames coming out of the pipe. This simple experiment proves that it's not just an air, it's an air mixed with flammable gases. Moreover hot air is worse than cold air for burning, since cold air is denser.

@stovemods8231 Жыл бұрын

@@beboba2498 I assume it matters where you inject the air into the fire. Apart from that somebody else pointed out the following (quote): "some wood gas is drawn downward thru the bottom holes of the inner burn pot and mixes with the incoming air providing a hot fuel air mixture at the jets, not just hot air." So as you said, it might not just be clean air but a mixture. I find it hard to tell for sure but sounds possible to me.

@adventurousandrew4442 6 жыл бұрын

The main idea of gas transporting is missing in your video..

@lorenhusky2717 6 жыл бұрын

Video is insanely quiet. Please crank your mic or talk louder!

@stovemods8231 6 жыл бұрын

Sorry, just using my phone for this.

@mp180170 3 жыл бұрын

Loren Husky turn you volume up!

@misterbadguy99 6 жыл бұрын

please turn the intro audio down. it's so loud :(

@stovemods8231 6 жыл бұрын

Sorry, I know. I am not the best editor but I will try to fix it in future videos!

@grumpyauldman 3 жыл бұрын

Tip ... if you're going to claim to explain something you should understand it first. This explanation is not correct as it implies that only air is drawn up the sides where it's actually air mixed with the wood gas that is con ected with it from underneath the combustion chamber.

@stovemods8231 3 жыл бұрын

Thank you for your insight, that makes a big difference. Always happy to learn something new :-)