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Post by BenAlexanderT on Jul 11, 2020 8:23:49 GMT -8
I think that you shouldn't cook while the burn cycle is at its highest point anyway since it's going to destroy the food you have in there  When I use my batch box as an oven, I put the food inside, once the coal phase starts. So, the firebrick is at a high temperature and the coal delays the cooldown of the firebricks  This way you don't lose any efficiency and there is no need to alter an already working design |
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Post by foxtatic on Sept 18, 2020 11:12:07 GMT -8
Hey all, first off Many thanks to Peter for pioneering this work! I've been studying hard on this development thread and want to do a build based on his Sketchup of a brick version. I'm ready to start gathering materials but am running into an issue: The yellow bricks measure 216 x 108 x 54mm on the sketch. The standard fire brick size available is 228.6 x 114.3 x 63.5mm (9 x 4.5 x 2.5 inches.) The length and width scale up just fine compared to the sketch, both 5.5% longer and wider. But the thickness scales differently- the 2.5 inch bricks would be an additional 9.5% thicker on top of the 5.5% scale up. 1. Since height and width scale up evenly, it would just be the wall thickness that is not to scale. Would the 9.5% thicker walls be an issue? 2. Another repercussion of 2.5 inch bricks is the depth of the port. I see that 2 inches is standard for port depth for any size batch box so would adding half an inch be an issue?  |
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Post by peterberg on Sept 19, 2020 0:38:06 GMT -8
1. Since height and width scale up evenly, it would just be the wall thickness that is not to scale. Would the 9.5% thicker walls be an issue? Nothing to worry about, just take the width of the brick as the base number and you're fine. The only thing that happens is there's more mass in the core, so it'll take slightly longer to come up to operating temperature. It helps to insulate the core all around. 2. Another repercussion of 2.5 inch bricks is the depth of the port. I see that 2 inches is standard for port depth for any size batch box so would adding half an inch be an issue? Latest thoughts about that particular point: the depth of the port equal to the width is an ideal situation. That said, any adverse effects comes into play when depth is twice as large as width, or the other way around. With that in mind, you could use those same bricks for an 8" version and be well within tolerances. |
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Post by scottiniowa on Sept 25, 2020 9:02:14 GMT -8
With the "Double Shoebox Rocket mark II" drawn out very well and proven, has there been a general consensus of what to marry it to? Since it is larger (longer than my readily available barrels) I can make it work, but in reality of my area of heating, just building for long term radiant heat will suffice nicely.
If this has been discussed, I have perhaps missed it, and please just point me in the right direction.
I have a fair bit of space, and standard 8' ceiling, my chimney port is at 5' high, but draft would be excellent.
thanks in advance.
Scott
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Post by scottiniowa on Sept 25, 2020 9:04:26 GMT -8
I might add, this is for a standard 6" OPEN stove, just as Peter has posted drawing for. NO changes.
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Post by peterberg on Sept 26, 2020 0:24:41 GMT -8
With the "Double Shoebox Rocket mark II" drawn out very well and proven, has there been a general consensus of what to marry it to? As far as experience goes, the DSR2 is able to serve about the same range of heating appliances as the original batchrocket can do. The DSR2 is a bit more picky about restrictions and friction spots I might add, presumably because of the absence of a real riser tube. So a piped bench I'd classify as a no-no, but proper bells and hollow benches have been implemented already with commendable results. A start bypass would be a real bonus for a wet and cold heater. Sizing methods of bells and so on are the same, no drastic differences as far as I am aware of. |
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Post by scottiniowa on Sept 28, 2020 14:40:25 GMT -8
With the "Double Shoebox Rocket mark II" drawn out very well and proven, has there been a general consensus of what to marry it to? As far as experience goes, the DSR2 is able to serve about the same range of heating appliances as the original batchrocket can do. The DSR2 is a bit more picky about restrictions and friction spots I might add, presumably because of the absence of a real riser tube. So a piped bench I'd classify as a no-no, but proper bells and hollow benches have been implemented already with commendable results. A start bypass would be a real bonus for a wet and cold heater. Sizing methods of bells and so on are the same, no drastic differences as far as I am aware of. Thought I had note to myself for some kind of formula for mass (and I know this varies with the mass type) but can not find. So Peter, you said "sizing methods of bells and so on are the same" is there somewhere in the huge wealth of information presented on this forum, this "sizing method" I will be glad to study it at length before I ask any foolish questions. I just can't find such an topic. By the way, I did run a test burn on the Double Shoebox Rocket Mark 2, (6") (dry stacked) and all went very well. It will be just that much better when tightly done for good. thanks in advance. |
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Post by josephcrawley on Sept 29, 2020 3:32:23 GMT -8
Thought I had note to myself for some kind of formula for mass (and I know this varies with the mass type) but can not find. So Peter, you said "sizing methods of bells and so on are the same" is there somewhere in the huge wealth of information presented on this forum, this "sizing method" I will be glad to study it at length before I ask any foolish questions. I just can't find such an topic. By the way, I did run a test burn on the Double Shoebox Rocket Mark 2, (6") (dry stacked) and all went very well. It will be just that much better when tightly done for good. thanks in advance. Riser diameter / Internal Surface area 12.5 cm (5") ISA 3.7 m² (39.8 sq ft) 15.0 cm (6") ISA 5.3 m² (57 sq ft) 17.5 cm (7") ISA 7.2 m² (77.5 sq ft) 20.0 cm (8") ISA 9.4 m² (101 sq ft) 22.5 cm (9") ISA 11.4 m² (123 sq ft) 25.0 cm (10") ISA 14.7 m² (158 sq ft) This is the bell sizing chart from batchrocket.eu |
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Post by scottiniowa on Sept 29, 2020 9:51:33 GMT -8
note to myself for formula for mass Riser diameter / Internal Surface area 12.5 cm (5") ISA 3.7 m² (39.8 sq ft) 15.0 cm (6") ISA 5.3 m² (57 sq ft) 17.5 cm (7") ISA 7.2 m² (77.5 sq ft) 20.0 cm (8") ISA 9.4 m² (101 sq ft) 22.5 cm (9") ISA 11.4 m² (123 sq ft) 25.0 cm (10") ISA 14.7 m² (158 sq ft) This is the bell sizing chart from batchrocket.eu I am glad I asked, as I had less than 1/2 the square feet presently planned...I presume this "area" is the amount that has been found to scrub the heat in the most efficient manner, as long as the restrictions are low for the flow of exhaust. I also presume, the mass thickness, in this formula does not make to much difference? I think I am fortunate in that I have a huge supply of granite pieces of the same dimensional thickness (1 1/16" and up to 24" square, so can make a nice "bell" path of nearly any dimension, and be able to preplan this shape/size before building. I now understand far better why some of these stoves are so large, I will keep working on the "plan" thanks again. |
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Post by josephcrawley on Sept 29, 2020 15:01:39 GMT -8
Riser diameter / Internal Surface area 12.5 cm (5") ISA 3.7 m² (39.8 sq ft) 15.0 cm (6") ISA 5.3 m² (57 sq ft) 17.5 cm (7") ISA 7.2 m² (77.5 sq ft) 20.0 cm (8") ISA 9.4 m² (101 sq ft) 22.5 cm (9") ISA 11.4 m² (123 sq ft) 25.0 cm (10") ISA 14.7 m² (158 sq ft) This is the bell sizing chart from batchrocket.eu I am glad I asked, as I had less than 1/2 the square feet presently planned...I presume this "area" is the amount that has been found to scrub the heat in the most efficient manner, as long as the restrictions are low for the flow of exhaust. I also presume, the mass thickness, in this formula does not make to much difference? I think I am fortunate in that I have a huge supply of granite pieces of the same dimensional thickness (1 1/16" and up to 24" square, so can make a nice "bell" path of nearly any dimension, and be able to preplan this shape/size before building. I now understand far better why some of these stoves are so large, I will keep working on the "plan" thanks again. ISA is the sum of the area of the top and sides not including the floor. Thickness will determine how long it takes to heat up and how long it will give heat back. The general rule is a hundred kilos per hour of storage. Also a thinner stove will get hotter on the exterior. |
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Post by scottiniowa on Oct 4, 2020 5:23:48 GMT -8
ISA is the sum of the area of the top and sides not including the floor. Thickness will determine how long it takes to heat up and how long it will give heat back. The general rule is a hundred kilos per hour of storage. Also a thinner stove will get hotter on the exterior. With my goal of the ISA of 57 ft squared, (6" size stove) Is this number "beyond" the outlet of the actual Double Shoebox Rocket Mark 2 ? Or do some of the sides of the stove count as well? (in the 57' figure) meaning perhaps everything on the actual stove, for actually calculations, other than the burn riser from lower to upper shoe box, (using NO changes to the full brick open design provided by Peter) with a few more tips on "sizing" ways, I will be able to show what I intend to do. thanks in advance. |
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Post by Orange on Oct 6, 2020 11:30:14 GMT -8
Peter, I was checking air inlets for DSR2. I assume "The total air inlet is 25% of riser cross section area" applies.
that 150mm model has CSA 177cm2 x 0,25 = 44,25cm2
but has 2 air inlets in the metal frame 5,6 x 3,5cm x 2pc = 39,2cm2
does it need more air or it works fine like this?
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Post by peterberg on Oct 7, 2020 2:34:45 GMT -8
Hmmm... DSR2 is a bit more sophisticated. It's a single air inlet which is more than 25% of the riser's csa. The primary air is quite a bit larger than strictly needed, for a reason. It's different in that there are several changes in direction before the air arrives in the firebox. This convoluted air path doesn't pose much in the sense of friction when the heater is started up, which is good because initially the chimney draw is not strong. The more volume of air is pulled through, the more friction there will be so the primary air will pull more air in but not overly so. In sharp contrast with the secondary air channel which is placed right behind the combined air inlet and is able to pull progressively more air in while the fire is growing.
In short: during a burn the ratio between primary and secondary air is changing quite a bit, in favor of the latter. This is done intentionally, because this emphasis shift is exactly what the combustion process is asking for.
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Post by Orange on Oct 7, 2020 3:55:25 GMT -8
ok tnx, so these two side openings are large enough! |
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Post by peterberg on Oct 7, 2020 4:19:11 GMT -8
Yes, absolutely.
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When I use my batch box as an oven, I put the food inside, once the coal phase starts. So, the firebrick is at a high temperature and the coal delays the cooldown of the firebricks 
This way you don't lose any efficiency and there is no need to alter an already working design 
