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Concrete block rocket stove

 
pioneer
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Location: Southeast Missouri
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OK, I'm relatively new to the permaculture world, and I know that concrete block rocket stoves as seen on Youtube aren't exactly green, nor efficient, nor much of a rocket.  That being said, I like trying new things and wanted to give it a go.  Right now all our time and energy when we get out to our property is devoted to building our house so we can get moved out instead of having to drive back and forth on days off.  I love bbq, and I love cooking outdoors, so once we get moved into our home I'll be building a pavilion constructed similar to a Viking or Saxon house to house a rocket oven, rocket stove, smoker, and grill.  We use our fire pit or my little Weber grill to cook when we go out, and I thought since I already have concrete blocks, why not give a concrete block stove a go.  I know the concrete blocks won't be very durable, put at $1 each I'm not out a bunch of money.  Any damaged or destroyed blocks will be broken up and added to the rocks around the driveway culvert to prevent erosion.

I used a masonry disc in my angle grinder to cut the end out of one of the blocks, the proceeded to crack the block when taking out the end that I cut.  Oops, but at least it doesn't pour smoke out through it.  I decided to use 5 blocks instead of 4 so my pan would be up higher and I wouldn't have to bend over.  I squished a piece of 4" duct that I had lying around so that it had a flat top.  That was put into the burn chamber and sticks placed of top of it.  The thought was that it will provide a channel for combustion air to be drawn it under the fuel.  I had a terrible time getting it to burn at first.  I took the top block off and was able to get a good fire going.  When I put fifth block back on, it continued to burn well.  I was impressed with how much heat I was able to get out of twigs and small branches I picked up off the ground.  It was much more efficient to use for heating a pan of beans than the fire pit.  Instead of using several logs to get enough fire for cooking, I used a bunch of sticks I picked up off the ground.  Pretty cool!

Rocket-Stove.jpg
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Rocket Stove, version 1
 
gardener
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Location: Galicia, Spain zone 9a
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I think I will try this. We have the blocks, we have the technology .
 
pollinator
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Wet cinder blocks can explode if exposed to a lot of heat. I presume it's the water inside expanding under the heat.
 
Mandy Launchbury-Rainey
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Graham Chiu wrote:Wet cinder blocks can explode if exposed to a lot of heat. I presume it's the water inside expanding under the heat.



But after reading this, we may not have the balls....
 
Graham Chiu
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Just stack dry fire bricks to make your rocket stove for cooking. Concrete is formed cold, but fire bricks are made inside high temperature ovens.
 
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Sorry, I need X posts before I can create a thread?  I did not see the option.

I learned about rocket stoves a while ago and had two failed attempts.  I cannot find proper fire bricks in my part of rural Arizona--or Phoenix.

I tried to modify The King of Random's backyard foundry, but his design relied on thermal mass, not insulation.

Rocket stoves are supposed to burn cleanly, right?  How much smoke would you see from each type of coal?

Thanks!  Have a great day!
 
Graham Chiu
pollinator
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Maybe one of the admins can move your question into a new thread. Coal really burns hot and needs more oxygen. Haven't heard of it being used.
 
James Harold McNeil
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Thanks.  I keep reading posts, but I do not have any good questions or anything to contribute.
 
Posts: 91
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Cinder blocks don't need to be wet to explode.

When portland cement cures it is chemically binding water, when heated to a certain point it releases the water rather quickly. The reason you've seen youtubers getting away with it is most cinder blocks are pretty porus and also have higher flyash content
 
James Harold McNeil
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I am sure they do not use rocket stoves made with cinder blocks long enough for them to fail or they keep their failures to themselves.
 
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