New Rocket Stove

It’s been a while since my last posting, but I have been working on my rocket stove and I’d say it’s just about done. My first stove was pretty small, measuring 6″ in diamater inside and 10″ outside. Well, the new one is made from a 55 gallon drum.

IMG_0060.jpgOne of the big lessons from the other stove is that airflow is key. I recently had the furnace in my house replaced and I had the guys leave the old one behing so I could scavenge for parts. One of these parts is a blower fan.

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Next, I needed a way to distribute the air into the combustion chamber (how’s that for technical jargon?) If you look closely or click on the image for a larger view, you’ll see that I’ve drilled holes on one side of each of the tubes. This is also to cause a swirling. I want the air to move around as much as possible before leaving.

Here are some shots of the barrel from below. This should give you a better idea of what’s going on.

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And here’re a couple inside shots.
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Next, I created some forms so I could line the inside with a cement, sand, perlite mix. The perlite is to make it a bit insulating.

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Instead of removing the forms, I just burned them out.

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Here are some shots of the stove in action.

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A last optimization on the stove is a lid. I haven’t tried it yet, but I think it will help it burn even better.

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Stove performance

So far, I’ve been very pleased with how the stove operates. I’ve been able to burn sawdust, woodchips, firewood and construction scraps. The main issue is with the sawdust. The problem there is that as the upper layers of sawdust turn to ash, it seals away the unburned sawdust. The fire dies down a bit and then when I stir it a bit, it fires back up. Figuring out a way to make it into blocks would be neccessary to really make it work with that kind of fuel.

Wood and woodchips burn pretty good though. I’m looking forward to seeing how the lid does.

3 thoughts on “New Rocket Stove”

  1. Miles,

    This was pretty interesting. You can weld?

    I could not see the swirling in this stove like the other one even though you designed it to do so. How about a picture with the fan off?

    How about a link to the motor controller?

    All this concrete work reminds me of a project I abandoned, maybe you can help. I wanted to make a tile mosaic table. The table is metal and is circular. The top is a metal ring with about a 1/2″ lip that is currently holding a round piece of wood. The vertical lip is about 3/4″ high. Ideally, I would have a round piece of concrete about 1/2″ thick that would replace the wood. I would add about 1/4″ of tile work on top.

    The problem is the concrete, I don’t know how to make it. I was thinking of making a rebar form in the lip and then flip it and the table upside down and fill with concrete. When it dries, flip it back.

    This idea seems reasonable but also feels like a hack. Thoughts?

    jr

  2. The “motor controller” is pretty simple. The fan operates on 110v, so it’s just a matter of a light dimmer switch. The electronic looking thing is a “kill-a-watt” which measures consumed power. You plug your fridge into it to see how much it’s costing you.

    Welding, I’ve wanted to learn for some time and when I decided to build a bigger stove last summer I had a the perfect excuse. I bought a welder off E-Bay and this is my biggest project to date. The welds are still un-attractive (not gonna say ugly) but getting better.

    It’s a downhill slope though. I’ve avoided learning metal working, but I’m a gonner now.

    On the concrete, here’s my thought. Get a piece of masonite large enough to cut a circle out of it. Masonite is the brown stuff that peg board is made out of. Cut a circle. Do you have a router? Take a board and use it as a pivot to guide the router in a circle. The stuff cuts pretty easy though so you can probably do it by hand.

    Put the masonite in table. Get some hardware cloth. You should be able to find that in the chicken wire section of homedepot. Go to the tile section and get some self-leveling thinset. You mix it up kinda runny and pour it in the table to the desired level.

    Now that I think of it though, there’s an easier way. Just get a sheet of hardibacker/cement board and cut a circle out of that. A jig saw cuts it ok. The stuff is intended as a backer for tile. it comes in 1/4″ and 1/2″ sizes. make up the remaining 1/4″ with a piece of plywood.

    The tiling part is easy. I think that’d be a great activity for the kids to make a mosaic.

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