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Post by exoplasmic on Jun 29, 2015 14:48:40 GMT -8
First Post. www.dropbox.com/s/9qc5dooj7szc2wb/newdimension2bells.tiff?dl=0.. (and first time using drop box link).[/p]
I have 34 feet of 8 inch double wall chimney pipe. My chimney will be installed soon by a professional, all according to building codes.
The room is 28 x 60 (1680 square feet; 156m2)(walk-out basement, un-insulated poured-concrete walls; 9 foot ceiling, concrete floor). Detroit, Michigan had a cold winter 2015 with typical high of 20 degrees Fahrenheit (-7 C). The top of the chimney will be above the peak of the 2nd story roof (12/12 pitch; Cape Code style house).
I have a couple questions about how to build my "batch box" 8-inch system. I would like 2 bells (see picture link above). I read somewhere on this board that an 8 inch system should get 7 m2 (square meters) of internal surface area. There will only be brick used for bells. For my first draft, I am planning on the riser within the first bell. The second bell will have a surface area (minus the floor) that is 85% of the first bell. Bell 1 and 2 share part of a wall. So the equation to calculate internal surface area (ISA): 7 m2 = x + 0.85x, where x is the size of the first bell's internal surface area. So x = 3.8 m2 and the second bell is 3.2 m2. If I use the actual dimensions of the bell and don't consider the riser the dimensions are 11.5 inches wide, 70 inches tall and 40 inches long. That would make the bell have 7670 inches squared (in2); 4.95 meters. The second bell, as drawn in the jpg file, is 40x57x11.5 = 6332 in2 (4.1m2)(2280+2280+460+656+656). The total internal surface area is 5m2+4m2=9 m2!
Question 1: Should I subtract the riser out of the first bell when calculating internal surface area? Question 2: Is the total too big? Question 3: Should I use 7 m2 as the exact ISA of the bells?
Question 4: Also, can I make the floor of the bells lower than the fire-box floor?
I can make the bells wider than 11.5 inches (0.3 m) if that would be better for stability; less likely to tip over. I can, and may likely, make the system a zig-zag (z-shaped) instead of 12 feet linear. I have Sketchup Make. I will probably try to use the software to show the details before I start laying bricks. I'll share that if anyone is interested, but may need some time to learn sketchup tricks.
Thanks, Mike
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Post by satamax on Jun 30, 2015 3:26:58 GMT -8
Mike, the best thing to do, imho, is a temporary heater. Something like this, www.permies.com/t/44806/rocket-stoves/Cobbling-workshop-heaterAnd add barrels untill you stall it. Once stalled, you substract the surface of half a barrel or one barrel, that should give you the ISA your system can cope with. jmho.
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Post by exoplasmic on Jun 30, 2015 4:55:11 GMT -8
I like that idea a lot. Thanks. Can I have the floor of the bell(s) lower than the floor of the fire box by approximately 10 inches? 8-inch Batch Box wBells_2.tif (725.82 KB)
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Post by exoplasmic on Jun 30, 2015 5:22:55 GMT -8
I like that idea a lot. That would be better than building a system then finding out it is not working properly. However, if I build it (with new dimensions in link below) using clay slip as mortar I could adjust the walls bigger and bigger until it stalls. I have 250 new fire bricks. 200 used fire brick with rough edges. And 700 solid clay bricks. Plus about 50 8x9x6 fire bricks with a weird notch on one face. I also bought 250 lbs of castible refractory. I have a large kiln so I can cure the castible properly. Castible is for tops of bells and some other parts. www.dropbox.com/s/9qc5dooj7szc2wb/newdimension2bells.tiff?dl=0Can I have the floor of the bell(s) lower than the floor of the fire box by approximately 10 inches? I'm using a wood stove made of steel for the fire box. I cut the back out of it. The length or depth was only 17 inches and I need 23 inches for an 8 inch system. It is on a sturdy pedistle that I could cut off, but I like having the firebox off the floor. Mike
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Post by satamax on Jun 30, 2015 10:29:15 GMT -8
Mike, i've asked Peter before, and yes you can have the bottom of the bell lower than the firebox. His workshop heater had the firebox at waist height.
The reason for me to use barrels for the bell test, is that metal sheds heat faster than a brick bell, so it stalls faster. Which gives you a good dimension for a brick bell, in the worse case scenario, with a foggy day, no wind or a bad wind etc!
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Post by exoplasmic on Jul 1, 2015 5:18:19 GMT -8
What if I make the bells higher by one course of brick at a time? Then I could see where it stalls. I'd keep the internal surface area size of second bell as close as possible to 85% of the 1st.
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Post by shilo on Jul 1, 2015 9:58:14 GMT -8
don't use the metal
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Post by satamax on Jul 1, 2015 10:42:06 GMT -8
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Post by shilo on Jul 3, 2015 2:04:56 GMT -8
"I'm using a wood stove made of steel for the fire box"
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Post by satamax on Jul 3, 2015 3:08:01 GMT -8
"I'm using a wood stove made of steel for the fire box" Yep true, can be done, but that's wasting efficiency.
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Post by exoplasmic on Jul 3, 2015 17:50:00 GMT -8
The metal box will be lined with firebrick on top, sides and bottom, and measure exactly as Peter van der Berg describes. The inside top of the stove's firebox will be a cast slab of refractory, when I get around to making it. It will only be 1.5 inches thick and will not fit perfectly snug against the metal top, but almost snug.
The reason I would like to use the stove is for the nice door with glass. And, I already cut the back off the stove because the only dimension that the metal box could not accommodate was the depth. It was 17 inches deep and I need 23.1 inches. The air supply is perfect too: 10 square inches.
And if I don't use it, what would I do with a steel stove with no back?
If you really think it would affect the efficiency, by shedding too much heat from the fire chamber, I'll cut the front of the stove off and just use that for the front of the firebox. The rest would be brick. Or, I could cut the sides and top off the stove leaving just the floor and the front. That way I can keep the pedistle that it sits on. In that case, I could make the top slab of refractory thicker for higher heat inside the firebox.
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Post by mkrepel on Jul 4, 2015 15:25:15 GMT -8
It sounds like you have it mostly figured out. Having your metal firebox completely lined with fire brick will make it at least as good as the setup in which Peter did most of his testing. He had at least one side that was glass. It is a good idea not to have the fit too tight. The metal will expand and contract differently than the fire brick, but you probably already figured that in. How will you install your secondary air if you use the whole metal stove? Do you plan on cutting a hole somewhere to supply that?
What you are doing sounds similar to an idea I had for a workshop heater. Please post pics as you progress.
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Post by exoplasmic on Jul 5, 2015 18:43:54 GMT -8
Yes, I plan on running the p-channel for air exactly as Peter van der Berg suggests. There's already a hole in the top from the original exhaust pipe. I plan to cover it up with bricks. The metal p-channel has to be welded steel. I have to enlist a friend to make this part for me. I want him to teach me how to mig weld with wire feed. Also, here are my new plans that show the bell going all the way to the floor: www.dropbox.com/s/uri5w6cjlt8pe5e/8-inch%20Batch%20Box%20wBells_low_res.jpg?dl=0...and the internal surface area calculations: www.dropbox.com/s/pfvbnc6rb2f100v/ISA_calc.jpg?dl=0I'll share pics of progression of the build. I'd like to test efficiency with temp, CO and O2 probe. Is that going to be expensive? Any suggestions on brand, website, make or model? Thanks, Mike
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Post by peterberg on Jul 6, 2015 0:56:18 GMT -8
Hi Mike, Finding someone with a Testo 330 isn't easy. Buying one of those analizers is even more expensive. Where in the world are you located?
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Post by exoplasmic on Jul 6, 2015 9:29:21 GMT -8
I'm in Fowlerville, Michigan. It's between Lansing and Detroit. Where are you located? I visited my relatives in Antwerp once (Van Leuvenhage and Baltazar). I also visited Amsterdam and Rotterdam back in 1989 for vacation, as well as a lot of other places using a Eurail pass.
I work in air pollution regulation. Our air monitoring group may be able to help me out. Also, our compliance folks do inspections and stack testing for the state of Michigan Department of Environmental Quality, Air Quality Division. I work there as a toxicologist but there's a lot of collaboration throughout the division.
I'll start by doing a Google search on the unit you mention. Craigslist, Amazon etc., may also have something too. Thanks for the tip.
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