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Post by johndepew on Mar 29, 2015 13:21:33 GMT -8
This morning I threw together a little different conviguration in the driveway to test this idea: Basically I turned the tall dimension of the batchbox sideways, so it was roughly 9 inches tall and 13 inches wide. Same port dimensions as usual and a 48 inch refractory riser inside a barrel. 2 inch pipe along the firebox floor from the front for secondary air just ahead of the port. My cooktop is roughly 16x24, and I thought, wouldn't it be cool to be able to bake a 12" pizza on the firebox floor? I don't have a testo or anything, but it rocketed quite well once everything warmed up, boiled a quart or so of water in about 5 minutes, and seemed to burn clean with the air intake closed down to normal dimensions. Definitely worth some more experimentation, I think.
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Post by ericvw on Mar 29, 2015 17:59:58 GMT -8
johndepew- what is the height of your port into the riser? Eric VW
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Post by johndepew on Mar 30, 2015 17:15:44 GMT -8
ericvw-in this configuration, it ended up being the full height of the firebox, 9", which I don't think is ideal, but that's how it worked out with the materials I had handy.
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Post by johndepew on Mar 30, 2015 17:17:20 GMT -8
The riser is cast with the port size according to the spreadsheet, but the cooktop butted up against it and covered the top half inch or so. Do you see a glaring problem in this?
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Post by ericvw on Mar 30, 2015 17:52:41 GMT -8
Shoot- I'm no expert johndepew! If the think rockets, it's a rocket! Now then, pics ARE in order, sir!  |
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Post by shilo on Mar 30, 2015 22:46:24 GMT -8
peter try the horizontal box and find it's not good
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Post by johndepew on Mar 31, 2015 7:08:03 GMT -8
shilo I"m in no position to argue with Peter. I do think that our goals may differ slightly, as my standards of efficiency are probably not as high as his at this point. ericvw Here is a picture of last night's configuration, more or less what I hope to install inside. The space below the firebox has a horizontal baffle halfway up that runs from the back to about 12" from the front, routing the gas from the bell under the firebox to the front wall, where it falls below the baffle, reverses direction, and moves out the chimney exit at the bottom rear. I think the whole chimney may have to be insulated to pull this off. In the final installment, I also plan to put a bypass flue out the top rear of the bell for preheating and summertime use.  Last night after I stacked this all up, I fired it and the thing started audibly pulsating, shooting flames very strongly out the top of the 44" riser-I could see through some small cracks in the bricks. Will it do this when everything is mortared in place? And what causes that kind of behavior?
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Post by ericvw on Mar 31, 2015 17:15:26 GMT -8
johndepew, Nice! If it's worth doing, experimenting is the way to go. Help me out if you can, for some reason (long day at work a good one?) I can't picture what you're describing. Can you sketch on a napkin or something exactly what you've done there, internally? If ya can't, that's fine. Just curious.
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Post by Daryl on Apr 1, 2015 2:08:31 GMT -8
This morning I threw together a little different conviguration in the driveway to test this idea: Basically I turned the tall dimension of the batchbox sideways, so it was roughly 9 inches tall and 13 inches wide. Same port dimensions as usual and a 48 inch refractory riser inside a barrel. 2 inch pipe along the firebox floor from the front for secondary air just ahead of the port. My cooktop is roughly 16x24, and I thought, wouldn't it be cool to be able to bake a 12" pizza on the firebox floor? I don't have a testo or anything, but it rocketed quite well once everything warmed up, boiled a quart or so of water in about 5 minutes, and seemed to burn clean with the air intake closed down to normal dimensions. Definitely worth some more experimentation, I think. This is how I ventured into tandoori cooking. I was building brick rockets and saw how hot the brick riser became and how long it held the temps. So yes, I do believe you could bake in the firebox. It is basically the same principle as the standard wood oven. |
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Post by satamax on Apr 1, 2015 2:46:39 GMT -8
Johndepew, so, does that cooking plate get hot? Daryl, i've done that two years ago, with the green machine. Don't know if it was the first test, but it was not far  |
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Post by johndepew on Apr 1, 2015 6:43:24 GMT -8
satamax, I'm actually a little concerned about the cooking plate being too hot to cook on when the fire is in full burn. It puts out a LOT of heat. I haven't yet tried to bake inside. I think for long baking your idea of putting some sort of slabs or bricks on top of the cooking plate will probably be an easy solution. ericvw, Here's a picture of the firebox and back wall with port.   And a quick sketch of the whole machine, in theory. I haven't gotten it to draft very well outdoors in warm weather with no mortar 
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Post by ericvw on Apr 1, 2015 13:50:15 GMT -8
johndepew, Well, I see you've definitely had a fire in it! Do you think no mortar is the main reason for poor draft? By this I mean if peterberg has said no go(by way of shilo mentioning it), I feel the longevity of the thing my be questionable... That said, it never hurts to keep trying! Thanks for putting a sketch up, too. Seems a ways to go for flue gas, don't ya' think? But hey, this forum ain't subtitled " Experimenters Corner" for nothing! Eric VW
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Post by johndepew on Apr 5, 2015 15:20:19 GMT -8
Yeah, I've pretty much decided to eliminate the shelf thing and just leave the bottom part hollow. The idea behind was that was just to get the best heat extraction from a very limited footprint while building the firebox at waist height. If I just make everything behind and below the firebox one big chamber that pulls out the back, I think I"ll lose more heat, but it will definitely be easier to get it to draft. I tried baking a couple pizzas a few nights ago, with no mass on top of the cooktop, and it really didn't work too well, as would be expected. I plan to try it again with the cooktop covered up with brick. if that doesn't yeild satisfactory results, I'll probably switch back to the stock batchbox for this project and leave this idea for another time.
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Post by satamax on Apr 5, 2015 23:15:58 GMT -8
John, one thing which i have learnt; when baking with the batch box, you need to stop all draft. Otherwise, the air entering the stove washes all heat out of the firebox.
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Post by johndepew on Apr 6, 2015 14:05:43 GMT -8
That explains some things. I was pretty surprised at just how fast the thing cooled off. So I'm going to need to go to the trouble of having a pretty tight system before I can get a good idea of whether it will work or not...That might take a little time.
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