first homemade wood stoves vs. commercial MSR stove

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lugnut
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Joined: Sun Aug 25, 2013 3:06 pm

first homemade wood stoves vs. commercial MSR stove

Postby lugnut » Mon Sep 02, 2013 2:29 am

Hi, I made my first two wood-burning stoves today and have a few test results. I thought you all might be able to put them in perspective.

My motivation for making the stoves was simple annoyance -- I went on a backpacking trip where we boiled all our water for drinking and eating and I was annoyed at how much white gas I ran through. I usually use a commercial MSR whisperlite international with white gas. Meanwhile there was a lot of good wood around.

So my goal was to make something that was (in concept at least) back-packable, but could boil enough water to really be useful. For me, two cups of water at one time isn't really enough -- I have other people with me. I'm more interested in boiling a whole camping pan -- about 8 cups.

I made two stoves:
The first was the hobo stove described at http://www.i4at.org/surv/hobostv.htm .
The second was the rocket stove in this youtube video: http://www.youtube.com/watch?v=vwujZFK05rY . I didn't have any vermiculite, so for insulation, I used crumpled-up and uncrumpled "blankets" of aluminimum foil.

These both are based on a 1-gallon can, which makes them a bit large for backpacking, but it's still conceivable. Especially since my goal is 8 cups of water. The wood was dead twigs and small branches from a black locust -- which burns pretty hot, but can be a little hard to get started.

I also ran my MSR white gas stove for comparison. All the tests were indoors in my fireplace, so wind wasn't a factor.

The results:

Say what you want about commercial stoves, but the MSR worked really well. It took about 3 minutes to set up, 2 minutes to prime/heat up, and only 5 minutes to boil 8 cups of water. This is probably about as fast as my house's kitchen stove could do it.

The hobo stove, as described in the link, didn't really work. It took 0 minutes to set up, and 4 minutes to prime/heat up, but when I set the pan on the top of the can as suggested in the link, it squashed the fire. After I used some rocks to space the pan above the top of the can it took about 25 minutes to boil 8 cups of water... this included adding some additional fuel. It did have a kind of cool vortex look to the flames though:
Image

The rocket stove took 0 minutes to set up, 3 minutes to prime/heat up, and after that 19 minutes to boil 8 cups of water. It didn't use much fuel but it did require frequent tending. (In a seperate test, it took 4.5 minutes to boil 2 cups of water.)
Image

I'm sure the design and execution of these things could be improved, but I'm just curious how these times compare to what else has been made.

thanks!

-lugnut

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zelph
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Joined: Tue Aug 14, 2007 1:53 pm

Re: first homemade wood stoves vs. commercial MSR stove

Postby zelph » Mon Sep 02, 2013 7:53 am

Oxygen, Oxygen, and more oxygen

Top and bottom, inlets and outlets. :D Need more!!!!

Split your twigs and choose a different species. If you have "tree of heaven" available, use that. That species is an import that is readily available in towns and cities.

Get rid of the inner can and vermiculite idea. Get accustomed to lots of wood in the stove to get your 8 cups of water to boil with one load of wood. Lots of wood packed in such a way as to leave air passages between vertical stacked twigs and light from the top.
http://www.woodgaz-stove.com/

sudden
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Joined: Tue Apr 06, 2010 5:33 pm

Re: first homemade wood stoves vs. commercial MSR stove

Postby sudden » Mon Sep 02, 2013 9:46 am

Can't tell for sure but looking at the picture you missed something important on the rocket stove.
There should be a shelf where the wood feeds in. The bottom of the shelf is left open for air to come in under your sticks. Seems like you might have starved it for air.
"People are not persuaded by what we say, but rather by what they understand."

lugnut
Posts: 7
Joined: Sun Aug 25, 2013 3:06 pm

Re: first homemade wood stoves vs. commercial MSR stove

Postby lugnut » Mon Sep 02, 2013 2:43 pm

Thanks for the feedback!

@sudden, there was a shelf there in the feed tube of the rocket stove, it's just not visible in that particular shot because the fuel sticks are curving down. No question that the shelf made a difference -- I didn't have it fixed in place very well and when it was letting more air through, the stove seemed to be working better.

So, yeah, oxygen was an issue for sure.

@zelph, there aren't many better tree species in my area, especially if we're talking about things I would actually find while camping (which is my focus for this project). I used locust because I had it in my yard, but the most common species where I am are Douglas-fir, Western Redcedar, Red Alder, and Western Hemlock -- none of which are rated very well as firewood on this table. http://forestry.usu.edu/htm/forest-prod ... d-heating/ . Occasionally there is Bigleaf Maple, which is great firewood -- but it tends to be in wetter areas so your chances of finding it dry aren't that good.

So, just out of curiosity, what would be a fast time for boiling 8 cups of water on a portable wood-burning stove? Any design that is roughly the size of a 1-gallon can or smaller? cheers -

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zelph
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Re: first homemade wood stoves vs. commercial MSR stove

Postby zelph » Mon Sep 02, 2013 8:57 pm

with the right stove you should be able to boil 8 cups in 30 min. A number 10 can without the insulation and good oxygen in and out. a grate 1" raised up off the bottom. Make sure the entire top has good tinder and is evenly lit not just in the center.
http://www.woodgaz-stove.com/

lugnut
Posts: 7
Joined: Sun Aug 25, 2013 3:06 pm

Re: first homemade wood stoves vs. commercial MSR stove

Postby lugnut » Wed Sep 04, 2013 3:25 pm

zelph wrote:with the right stove you should be able to boil 8 cups in 30 min.

So I'm doing ok so far, then? Since my first two had times (combining the priming/pre-heating time with the actual cooking time) of 22 minutes (rocket version) and 29 minutes (hobo version)? Of course these were in the fireplace, so there was no loss to wind.

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zelph
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Joined: Tue Aug 14, 2007 1:53 pm

Re: first homemade wood stoves vs. commercial MSR stove

Postby zelph » Wed Sep 04, 2013 11:12 pm

lugnut wrote:
zelph wrote:with the right stove you should be able to boil 8 cups in 30 min.

So I'm doing ok so far, then? Since my first two had times (combining the priming/pre-heating time with the actual cooking time) of 22 minutes (rocket version) and 29 minutes (hobo version)? Of course these were in the fireplace, so there was no loss to wind.


he rocket stove took 0 minutes to set up, 3 minutes to prime/heat up, and after that 19 minutes to boil 8 cups of water. It didn't use much fuel but it did require frequent tending. (In a seperate test, it took 4.5 minutes to boil 2 cups of water.)


Yes, you're off to a good start. :D
http://www.woodgaz-stove.com/


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