Batch cookstove inspiration from Firespeaking and Lasse

[matt walker]

I spent some of last week traveling and have an awesome new thingy to share.

I went to Eugene to hang out with Max and Eva from , Lasse Holmes, Leslie Jackson, Kiko Denzer, and few other lovely people. Max, Lasse, and Kiko had been playing with variations of

They had most of the heavy lifting done when I got there, so I mostly got to relax and eat amazing cake, which was awesome. We put some finishing touches on the heater on my first day and ran a few tests the next morning. I don't have any graphs to share at this early stage as there is still quite a bit of development to do, but the initial results are very promising.

It's basically a side batch a la Adiel and Shilo, with a very short riser. Coincidentally, I had just been expressing my skepticism of short risers to Peter earlier last week. I was excited to see how this one did, and much to my surprise, it burned quite well. Not as amazingly complete of a combustion profile as our normal risered configurations, but still very clean and quite efficient. In it's initial set up, which can be tuned quite a bit, it was exceeding 80% efficiency with CO numbers down below 100 at times.

I'm really inspired and excited, so much so that I've been home just over 24 hours and already stacked up two more burn chambers of similar designs and had fires last night. There will be more on this in the coming weeks I'm sure. Max is planning a write up in his so keep checking over there, and I'll write up more as I go. I probably won't share many details of the internals and let Max, Lasse, or Kiko share what they would like about that. But, at this stage I'm thrilled with the possibilities here, and am so glad to have gotten to be a part of this process.

Here's a shot of the stove as I left it. The crew was working on the hardware so I'm sure it will be even more stunning once it gets the big windowed door on there.

[mannytheseacow]

That's a beautiful stove. Thanks for sharing that, Matt. The links provide some good drawings, too. It's awesome that they have that information out there.

I was thinking about something similar while I was away, too. The need for a shortened riser is certainly a factor with cooking surfaces, then I got thinking about your "broken riser" concept, and started wondering what the difference really is between a broken riser and a horizontal flue path. I suppose it's not as efficient as the batch as Peter designed it, but still probably worth the effort and so much more efficient than the alternatives.

Even though the cook stoves we were making in January were J cores, they always ran tremendously despite the sometimes limited riser length. All I could attribute this to was that the flue path was continued horizontally across the cooking surfaces before hitting exhaust, almost acting as a continuation of the riser. You guys are way ahead of me in the design aspect of what's going on... and perhaps this is a tangent from the batch cookstove you're showing.... just some thoughts.

Man, I love that cooking surface in the photo. And it's just begging for an oven!

[thickstrings]

That thing is really cool.....would really like to have one.... here are some more designs of various types .... http://www.ekonomka.se/

[thickstrings]

All though the stoves in the above post may not be rockets, they claim 95% eff. The hardware is the biggest problem with trying to make , as far as I can see....love me one with the oven ...except for I could only use it for about 2 months where I live.......to hot...Its a problem in the south with stoves that are to efficient...cold at night , then its 65 the day and you are opening windows.......not today though, as its still 27 outside....last week it was 70-75 during the day, 50's at night....my pizza oven was cranked. Just getting over the bread and cheese onslaught. Stromboli, Calzone...hmmm I think I"m ready again.

[pa_friendly_guy]

It will be awhile before I think about firing up the pizza oven here. High tomorrow is to be around 7* for a High, below 0* at night, maybe May or June would be better for me.

[matt walker]

Well, I'm not going to get any plans out anytime soon, so I just threw the whole photo album of my Brick Cook Stove build up, linked from my WS site.

It's here, if anyone would like to see the build photos:

http://walkerstoves.com/walker-brick-cook-stove.html

[matt walker]

I finally got around to filming a little intro to my cookstove, after a year of use. This should give you guys some more data, although it's mostly a non tech overview for the masses. Feel free to ask whatever, the basic gist of it is that I wouldn't change a thing. I am extremely satisfied with this one. Enjoy!

[dave brenneman]

awesome stuff, matt. I'd love a cookstove one day.

[matt walker]

Thanks Dave, it's great to hear from you. I'm planning on building one in the coming months if you'd care to come help. I think I'm building my little house finally, maybe even today!

[Nutcase]

Matt, this is very elegant.

Your secondary air thing ties into something I've been mulling over for a while now, as i've come to better understand how wood burns. Basically, as long as volatiles are boiling off, fuel temp is clamped like water in a boiling pot. Heat input controls rate of volatilization rather than temp. Too much volatilization can smother. A structure that heats secondary air can also reduce heat input to the fuel. So what about putting a thermo-siphon coil in the input to a J tube system to help control firecreep...Anyway, it looks like your secondary air is your main air, once the door is closed. It's rather like a torch, with regard to the volatiles, with embers keeping it lit.