Monday, January 17, 2011

Rocket Stove



I have been watching rocket stove videos on YouTube for some time now – they fascinate me.
These are stoves that are basically shaped in a J. The fuel goes in the lower horizontal end and the heat and flame exit the vertical part of the J at the top. They are extremely fuel efficient as all of the heat goes straight up to your pot. They are also efficient in that they take twigs and scraps.

I decided before Christmas that I’d eventually get around to making one. I think these would be just the thing for emergency off grid cooking. Some folks build beautiful ones. Some folks turn them into cob oven home heaters. Some folks charge way too much money for them if you want to buy one. Anyway, I had some free time today so here we go!

I won’t go into explicit detail concerning how I built mine – there is plenty of better stuff in video. Just go to Google video and type in “rocket stove” – you’re welcome. But the basics for mine were as follows. A friend from church gave me a popcorn tin for the outer container and I had some stove pipe of different diameters laying around for the guts. The wider pipe is vertical, the narrower stuff is the horizontal bit. I cut holes in the big popcorn tin and the vertical pipe with my angle grinder (thanks, Viking 1 for recommending I get one) and tin snips. I’m no artist with metal – the holes were ugly and ragged. This is just a prototype though.



On one video I watched, the instructor said to fill the outer container with vermiculite ( I THINK I remember that correctly – it’s not like I took notes). It is used to insulate everything and it doesn’t burn – I think.

So after cutting and fitting pieces it was time to go buy some vermiculite. Home Depot – no go. Tractor Supply – no go. Chinamart ...(Yes, I went there and I’m hanging my head in shame...) – no go. My wife said I should have ordered 50 pounds of it on the Internet a month ago because, “no one is going to have it now and we could use the excess in our garden”. Whatever...

Finally, the place I should have gone to FIRST – ACE Hardware – had it. At least they are semi-local and not huge corporate monsters...

Back home I assembled the pieces – they did not fit perfectly because I did not cut the holes perfectly so when I poured in the vermiculite and started tamping it around the stove pipe it spilled out of the gaps. So I filled the gaps with aluminum foil. Ugly. Un-professional. Hey, it’s a prototype and it’s for ME – I’m not selling them.

I drilled three holes just outside of the vertical pipe hole and put 1 ½” bolts through them to act as a pot rest or trivet or whatever.

Finally, I cut up a metal gallon soy sauce container (that was destroyed by sorghum but that is another story entirely) to serve as the shelf in the intake tube. You put the fuel on top of the shelf and air flows (rushes) in underneath it – thus creating the “rocket” I guess.

We needed to par boil some chicken for supper and I needed a test so we set it up outside and had a go. I rigged up a hasty wind screen of aluminum foil around the top to concentrate as much of the heat as possible on the pot.

Normally one would use twigs but our twigs are currently soaked so I split kindling even smaller to replicate twigs and used that. Start with a piece of newspaper shoved in the chute and feed the twigs across the shelf. Wow – these things DO work well. The only downside is it turned the botom of our pot black.



One thing I failed to do was insulate the bottom from the picnic table and now we have a scorch mark. Ah well, as my daughter says, “THAT’S why we can’t have nice things!”

Hey – I’ll see ya out there.

And Samuel said unto the cook, Bring the portion which I gave thee, of which I said unto thee, Set it by thee. – 1 Samuel 9:23

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If you have any comments I’d love to hear them.
If they really interest me, I may even post them.
You can reach me at Joe

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5 Comments:

At 21/1/11 10:27, Blogger Muddome said...

Congrats on your rocket stove. My wife and I are hooked on them. We've built several of different sizes and will be soon working on the rocket mass heater for our earthbag dome home.

 
At 21/1/11 13:57, Blogger Rhetoric Camel said...

That is awesome. Thanks for the info, I've never heard of them. I will be looking into these now.
No need to worry about looking ragged that's the joys of making your own things from home with limited tools.

 
At 23/1/11 05:50, Blogger Anji said...

I've never heard of this before. Does the 'rocket' effect mean that things cook quicker?

 
At 23/1/11 05:51, Blogger chinasyndrome said...

Ah,Wifes and Daughters!Working on a couple of designs myself.Everyone you make they get a little better!

China
III

 
At 24/1/11 05:59, Blogger Joe said...

Anji, I think "rocket" comes from the effect of wind/air rushing in and up. Things cook quicker with much less fuel as all of the heat from the fire is concentrated onto the bottom of the pan - unlike with a campfire where most of heat radiates out and away.

Also - you use "trash wood" - little sticks and twigs so using one in an emergency is very fuel-conservative.

 

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