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Post by sebgreen on Jun 14, 2011 3:59:03 GMT -8
Hi
I recently got interested in all of this rocket stove buisness and thought I might try making one myself to be able to cook outside in the summer without using the barbecue.
If you take a look at the pic attached, thats the sort of thing I'm looking at building; not the type with flames coming out of the top. My main aim is to make it as compact as possible( roughly 1 metre high) , hence the shared wall between exhaust and cooling chamber.
I would like to make it out of brick. Given it's usage (cooking and therefore no need for heat storage or long burning periods), is it necessary to insulate the combustion chamber or can it just be made from brick ?
Cheers
Seb
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Post by sebgreen on Jun 14, 2011 4:01:28 GMT -8
Oh, and also, if I bolt the metal cooking surface to the top will it crack the brick structure when it gets hot ? I'm guessing it will cause it needs to expand.
Cheers
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Post by Donkey on Jun 14, 2011 9:25:57 GMT -8
Heat risers work BEST when insulated. You could make it all out of brick and it will work. It will work better if it's insulated, though just insulating the brick really do anything for you.
I like using heavy gauge steel pipe as heat risers and insulating that really well.
Likely that it WILL crack the brick.
If you want to cook on it outside, why the down after the heat riser and the separate chimney??
My favorite wok stove is just open at the top with three cob blobs (or brick pieces) to allow flow around the wok.
As a general rule, the less stuff you put between the fire and the food, the better.
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Post by sebgreen on Jun 14, 2011 9:49:52 GMT -8
Hi, The only reasoning behind that design is because I dont want to get soot and residue all over the pans. Adding to that the rest of my family would probably rate it as "safer" if the fire is hidden  Having said that maybe the chimmeney is unnecessary and maybe to save on masonry I could use a kind of 'double J' shape or just scrap the chimmeny and just stick a hole. ( Illustrated below) I figures having that downdraft would give it more draw... |
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Post by canyon on Jun 14, 2011 9:52:43 GMT -8
Also, you might consider going with a horizontal fuel shelf approach (approvecho) for easier control and lighting. I have found that you do need quite the coal/ash pit area under the heat riser with a grate so it doesn't get choked out. The cooking plate will work much better if you have fins on the bottom for turbulence/ more efficient heat exchange (if you look on wood fired ranges they usually have them cast in to the cooking plates).  |
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Post by sebgreen on Jun 14, 2011 9:56:55 GMT -8
Also, you might consider going with a horizontal fuel shelf approach (approvecho) for easier control and lighting. Don't vertical fuel inputs have the advantage of having a more autonomous combustion ? |
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Post by canyon on Jun 14, 2011 22:47:29 GMT -8
Self governing combustion is not necessarily an advantage for cooking. For cooking you really want control of your heat. By the way, you don't need to have your exhaust go down after your cooking surface if you aren't going to use the heat at a lower level, however, having a vertical stack flowing up after will certainly help your draft. |
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Post by sebgreen on Jun 15, 2011 0:42:02 GMT -8
By the way, you don't need to have your exhaust go down after your cooking surface if you aren't going to use the heat at a lower level, however, having a vertical stack flowing up after will certainly help your draft. That's the problem, how can I have a tall vertical stack if I don't force the smoke down first ? If I wanted equal stack length without the exhaust going down it will be very tall ;D |
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Post by canyon on Jun 15, 2011 8:29:39 GMT -8
What is your height restriction? It doesn't need to be very tall and doesn't need to be masonry, even three feet would be helpful. If you have the downward flow my intuition says that you will have to do a primer fire or other preheat method to get the thing to draw when cold. If you have a height restriction then you are better off just exiting straight out the side. The heat riser is the stack of importance here. Just my thoughts. |
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Post by sebgreen on Jun 15, 2011 12:57:53 GMT -8
Hmm , I dont want to have to pre heat ... Hight isn't a problem I just dont want to make it to big ( money and garden size) Would this design be better. ( how tall should it be ??) Thanks for all your advice,  Seb |
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Post by sebgreen on Jun 15, 2011 12:59:03 GMT -8
The more this thread goes on the simpler my drawing gets ! Rock on !
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Post by canyon on Jun 15, 2011 19:26:42 GMT -8
If you don't have any height restrictions then I would do a short stack (could even be single wall steel or ss that you put on when cooking and remove between uses so the wind etc doesn't damage) after the cooking surface to get the exhaust out of the cooks face. Height of heat riser comes down to practicality of height for the cooking surface, make it as tall as you can. If you can work in an access door to the ash pit with a removable ash pan it will make clean out way more pleasurable. You can buy ready made cast iron ash doors and frames to set into your masonry from masonry stove supply houses such as north stone heat supply in Washington where I get mine (not sure where you are?). |
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Post by josephcrawley on Sept 22, 2011 11:57:57 GMT -8
You can definitely make the burn chamber out of bricks. Your best bet would be to use a blend of perlite or vermiculite mixed 50/50 with a pure potters clay. It may crack a little but will stay together. Plan on a 10% shrink as clay dries. You could also use a 50% saw dust mix and the saw dust will fire out when you get the bricks dry and hot enough.
You may also want to place the fire closer to the cooking surface instead of the long heat riser. This is the way a cookstove is designed and it seems in the enclosed stove with a chimney your thinking of it makes more sense.
I've had the same complaint about the rocket stove sooting up the pots. I switched to an outdoor wood cookstove I found at the scrap yard for summer cooking.
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