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Post by n8ivetxn on Sept 9, 2017 12:10:07 GMT -8
Hi y'all, this is my first post. I've been lurking for quite some time.... I really appreciate all the great minds and sharing of information, awesome forum
I had to stop reading threads and post my own. At first, I was so excited. After watching many youtube videos and reading sites, I was ready to get started, but one phrase keeps coming back to haunt me: the devil's in the details. Language is my thing, I am not a numbers girl. I'm also a very visual learner.... I'm seeing all these equations, and to be honest, now I'm doubting myself. People on youtube make it look so easy.... but then math happened. I never saw any of them with a measuring tape, much less a calculator!!
My greenhouse is 18L x 15W x 14H. It's very tight and has double wall polycarb sheeting (R-value is 1.54) and a brick floor. I live west of Olympia WA, halfway to the coast.
I was prepared to build a 6" J-tube with a 55 gal barrel and 6' long bench. For my application (greenhouse heat/PNW), do you think the 6" system will provide enough heat? Should I go 8"? Do I need a longer heat exchange?
- I have some photos, but can't get them uploaded. I keep getting a message that says this forum has exceeded its limit...bizarre.
What are your thoughts?
www.flickr.com/photos/158311195@N04/
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Post by wiscojames on Sept 9, 2017 15:29:23 GMT -8
You need to upload your photos to a third party service and link them in your post.
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Post by n8ivetxn on Sept 9, 2017 16:42:32 GMT -8
Thanks, got it! There should be 3 photos, available for all to see.....
Another thing.... I've been looking at Andrew Brunning's Endeavour page, I like his batch box.... all of this is so foreign, I don't know which way to go!
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Post by Dan (Upstate NY, USA) on Sept 10, 2017 18:03:16 GMT -8
I'd go the entire length of the back side of your greenhouse, one straight shot then out the wall and a vertical chimney outside that just goes over the roof... but that's me... 6" or 8" will work, you will have to fire the 6" more 2times for the same heat output as the 8inch.
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Post by pinhead on Sept 11, 2017 6:06:20 GMT -8
I'm partial to the Batch Box design, personally. A 6-inch batch box would be plenty for that space.
If you're measurement-averse, the j-tube is simpler because the Batch Box requires specific dimensional ratios in order to function well. On the other hand, there's a chart that you can easily follow showing the dimensions of the Batch Box. I'd guess 6-inch Batch Box or an 8-inch J-Tube would suffice.
I'd build a bench down the length of the greenhouse, though you should leave a gap between the bench and the wall - and insulate that gap if possible as well; you don't want to radiate 33% of the heat through the back wall. At the very least, in my opinion, a decent radiant barrier should be used in that gap.
How you build your bench will depend mostly on what materials you have on hand. I much prefer bells over tubes due to the bell's higher efficiency and simplicity (a bell is simply a large open chamber).
No matter which you choose to build, there's plenty of knowledgeable folks on the forum to bounce ideas back and forth with!
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Post by n8ivetxn on Sept 12, 2017 16:54:09 GMT -8
Thank you both so much for the input..... I really like the idea of a wall-length bench, but I have a water feature with a living wall at the far end. I guess I could dismantle them, but I'd rather work around them, if possible....
The Batch Box design is my favorite too. I saw the spreadsheet and I think I can navigate through that with little, or possibly, no help.
For the back wall, when you say "decent radiant barrier," would a 4x6x8 (concrete) brick wall be sufficient? I thought about adding a cement board attached to the wall, prior to setting the concrete blocks.
I also like the idea of bells, due to their efficiency, but I think I'm a little vertically challenged - the back poly sheets slant a little. I wish I had more time to experiment a little, before the weather changes... If people are using the tops of barrels and bells for cook tops, there must be tremendous heat rising off them. I'm scared that whatever I build, I'll melt the polycarbonate sheets! ....
I was hoping to start this 2 days ago, but now I have family coming in 2 days, so I have to wait until next Monday to start work.... I'll be posting more pics as I go along....and probably asking for more input!
Thanks again, y'all rock!
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Post by pinhead on Sept 13, 2017 5:01:03 GMT -8
Thank you both so much for the input..... I really like the idea of a wall-length bench, but I have a water feature with a living wall at the far end. I guess I could dismantle them, but I'd rather work around them, if possible.... The reason I recommended a full-length bench is so it can radiate fairly evenly down its entire length and heat the greenhouse evenly. I wouldn't dismantle and/or destroy what the greenhouse is made for (growing plants) for the stove, though. The Batch Box design is my favorite too. I saw the spreadsheet and I think I can navigate through that with little, or possibly, no help. For me, the most difficult part was the heat riser - because the better it is insulated, the better the stove will run. Sliding 1 inch of ceramic-fiber blanket inside a stove pipe is super easy and extremely effective. For the back wall, when you say "decent radiant barrier," would a 4x6x8 (concrete) brick wall be sufficient? I thought about adding a cement board attached to the wall, prior to setting the concrete blocks. Radiant barrier would be shiny metal - usually aluminum or stainless steel. Luckily, radiant barrier foil is fairly inexpensive: Radiant BarrierI also like the idea of bells, due to their efficiency, but I think I'm a little vertically challenged - the back poly sheets slant a little. I wish I had more time to experiment a little, before the weather changes... If people are using the tops of barrels and bells for cook tops, there must be tremendous heat rising off them. I'm scared that whatever I build, I'll melt the polycarbonate sheets! .... Bells don't have to be very tall! The bench, itself, can be a bell - I've built bells as short as a foot tall! The only requirement for a bell to work is for the inlet and outlet to be at the bottom of a large open space. For instance, in my work shop at my parents' place, I used a barrel split in half length-wise laying on the floor, covered with cob. A 55-gallon barrel is ~24 inches diameter so the roof of the bell was a measly 12 inches and it works wonderfully. I was hoping to start this 2 days ago, but now I have family coming in 2 days, so I have to wait until next Monday to start work.... I'll be posting more pics as I go along....and probably asking for more input! Thanks again, y'all rock! Good luck!
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Post by n8ivetxn on Sept 18, 2017 11:34:28 GMT -8
Excellent! That's encouraging .....a split barrel with cob?! That sounds so cozy, lol, I wouldn't get anything done...
Now that everybody is gone, I have a whole week to myself! I got some radiant barrier foil on order, it'll be here in a couple days, so I'm going out to get started on a foundation for this beast ;-) Since my floor is brick, I thought I'd put down a layer of sand, to help even the base.
.... I might pry the living wall just a bit and try to wedge some foil up behind it. It might help keep those plants a little warmer on that end....
Hopefully I'll have some progress pics later today,
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Post by pinhead on Sept 18, 2017 12:35:19 GMT -8
Excellent! That's encouraging .....a split barrel with cob?! That sounds so cozy, lol, I wouldn't get anything done... Now that everybody is gone, I have a whole week to myself! I got some radiant barrier foil on order, it'll be here in a couple days, so I'm going out to get started on a foundation for this beast ;-) Since my floor is brick, I thought I'd put down a layer of sand, to help even the base. .... I might pry the living wall just a bit and try to wedge some foil up behind it. It might help keep those plants a little warmer on that end.... Hopefully I'll have some progress pics later today, Just remember one thing when using any radiant barrier: It ONLY works in conjunction with an air gap! Reflection and emissivity by surfaces can ONLY occur in SPACE. The ideal space is any dimension 3/4" or more. Smaller spaces are also effective, but decreasingly so. Where there is no air space, there is conduction through solids. When a reflective surface of a material is attached to a ceiling, floor or wall, that particular surface ceases to have radiant insulation value at the points in contact.
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Post by n8ivetxn on Sept 18, 2017 13:24:03 GMT -8
"Mind the Gap!" I'm glad you gave some dimensions, I wondered how much gap...."at the points in contact," I also wondered about that... interesting stuff....
Question: If I decide on the Batch Box (I'm leaning that way), I've read that a circular heat riser creates more turbulence than the square riser (which makes sense) - can I smooth some mortar in the corners to create some curve? Is there a better method for creating better turbulence in the square riser? I know you can cut firebrick to form a circle, but I'm not sure I could do it without creating other issues.
Ok, I'm going to hop over and re-read the dimensions spreadsheet....
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Post by n8ivetxn on Sept 18, 2017 20:43:42 GMT -8
Instead of using mortar to round out the corners, I think I'll go ahead and try cutting them to shape. I just hope I don't ruin a bunch of them....
So, just to be clear, if I'm building a 6" Batch Box, I use the following data:
Heat Riser Dimensions: 1’ riser gap, 2” gap around sides Length: 43 3/16
Box Dimensions: Width: 8 10/16 Height: 12 15/16 Depth: 17 4/16
Port Dimensions: Width: 2 3/16 Height: 9 8/16 Depth: 2
P Channel: Width: 2 3/16 Height: 10/16 Overhang: 10/16
.....And, all of these are internal dimensions, given in inches? .....interesting. I hope this thing works. It sounds too good to be true.
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Post by peterberg on Sept 18, 2017 23:59:09 GMT -8
Yes, all dimensions provided by the spreadsheet are internal. And yes, the thing will work like that, no doubt about. I feel a bit suspiciously about that 2" side gap though, all the tests were done with a bell set-up, primitive in most cases. So a side gap around the riser has been no less than 6" in the reference design.
It would be a good idea to set up the combustion core in the garden and see what is going on for yourself. Beware though, dry stacking bricks isn't a good idea, too much leakage and it won't work as promised.
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Post by pinhead on Sept 19, 2017 5:24:12 GMT -8
I agree with Peter. In my stove, the OD of the 6-inch riser is eight inches and the barrel is 24 inches ID. I also have a good 10 to 12 inches above the riser. The heat riser has always been the most difficult part for me when building rocket stoves. Luckily I've found a super simple way! It's so easy anyone can do it! I use an inch-thick ceramic fiber blanket as my heat riser, formed inside an eight-inch stove pipe. The density of the ceramic-fiber holds itself in shape. It works wonderfully. If you're good at salvaging materials, you can find superwool beneath the glass of a glass-top cook stove. If you'd rather not salvage materials - and would like to have plenty extra for future builds - Walmart sells the stuff: UNITHERM Ceramic Fiber BlanketThis is the inside of my riser:
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Post by n8ivetxn on Sept 19, 2017 7:43:38 GMT -8
Yes, all dimensions provided by the spreadsheet are internal. And yes, the thing will work like that, no doubt about. I feel a bit suspiciously about that 2" side gap though, all the tests were done with a bell set-up, primitive in most cases. So a side gap around the riser has been no less than 6" in the reference design. It would be a good idea to set up the combustion core in the garden and see what is going on for yourself. Beware though, dry stacking bricks isn't a good idea, too much leakage and it won't work as promised. Hi Peter About the 2" gap - I took that part from some other thread, here on the forum. I think I must've misunderstood what was being discussed.....thank you for correcting it.... So no less than a 6" gap.... Oh, I saw something else last night, reading a thread. A gentleman said his chimney would be 8' tall. There was discussion that this was not tall enough and he would have problems. How tall should a chimney be for a 6" system? I realized I forgot to get a hacksaw in town yesterday, so I need to get one for cutting the feed chamber bricks..... I will set it up in the yard for a test. I'm really excited about this!
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Post by n8ivetxn on Sept 19, 2017 7:53:50 GMT -8
I agree with Peter. In my stove, the OD of the 6-inch riser is eight inches and the barrel is 24 inches ID. I also have a good 10 to 12 inches above the riser. The heat riser has always been the most difficult part for me when building rocket stoves. Luckily I've found a super simple way! It's so easy anyone can do it! I use an inch-thick ceramic fiber blanket as my heat riser, formed inside an eight-inch stove pipe. The density of the ceramic-fiber holds itself in shape. It works wonderfully. If you're good at salvaging materials, you can find superwool beneath the glass of a glass-top cook stove. If you'd rather not salvage materials - and would like to have plenty extra for future builds - Walmart sells the stuff: UNITHERM Ceramic Fiber BlanketThis is the inside of my riser: Wow, that is cool! And it's so simple! - I should get a roll of it, I may be building some more of these things, lol.... So, you use a barrel, instead of a brick riser? Ok... I was thinking mine would be brick. No particular reason.... And you have a lot of "gap" in there too, nice. If I use brick, would I need to make the top removable for maintenance or any other reason? I just thought of something else. I don't know a welder out here..... I saw a suggestion on this forum, about using threaded pipe with an elbow (to make L shape) as a substitute for the p-channel. Does that sound feasible? What are your thoughts on the height of a chimney? Tomorrow my radiant barrier foil will be here! Thank you both for the words of wisdom
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