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Post by belgiangulch on Mar 9, 2020 20:45:28 GMT -8
Hi All; Getting close to having everything ready to switch my shop J tube over to an 8" batch box. Few more pieces needed and I'll be ready to tear into it.
Was out in the shop yesterday,building a Mock up with my Skamol insulated bricks. Turns out they are 9 1/8" long ... not the standard 9". Good thing to know. I built it with an octagonal design to set the 5 minute riser on. It looked really good. But then I started thinking maybe I'm overbuilding?
I'm wondering if I can just go with 8" square base ? Much simpler to build and lot less bricks needed. I seem to recall reading, that there was no noticeable difference?
What is the current thinking about this?
If I were to build with a square base do I need to cut angled brick for the bottom back edge?
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Post by peterberg on Mar 10, 2020 5:43:48 GMT -8
I built it with an octagonal design to set the 5 minute riser on. It looked really good. But then I started thinking maybe I'm overbuilding? I'm wondering if I can just go with 8" square base ? Much simpler to build and lot less bricks needed. I seem to recall reading, that there was no noticeable difference? In case you can, build a square riser with the Skamol bricks. Close to ideal, simple to build. The difference with a round or octagon riser is small, one would need a Testo analizer to proof it's there. But... in a very early stage I found out halfway changing from square to round is problematic. Didn't burn that well, felt second rate so were the results. Best to have it round from top to bottom, or square for that matter. If I were to build with a square base do I need to cut angled brick for the bottom back edge? In a square riser, no. In a round or octagon riser, doubtful. Especially in combination with a floor channel.
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Post by belgiangulch on Mar 10, 2020 5:54:16 GMT -8
Thank You Peter;
I will see if I have enough Skamols on hand to build a square riser with them.
If not, then in order to use my 5 minute riser I should stick with the round base design.
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Post by peterberg on Mar 10, 2020 6:11:29 GMT -8
An 8" batch box rocket is a hefty heater, this design tend to scale up rather fast. You're sure you want such a biggie?
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Post by belgiangulch on Mar 10, 2020 6:32:38 GMT -8
Hi Peter; Yes, I think so, this is in a 25' x 30' high ceiling, only marginally insulated auto shop.Where the large doors will be opened from time to time.
My bell was sized to be apx 6" batch size (its currently an 8" J tube) , so I expect to be raising the walls higher to capture the extra heat.
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Post by peterberg on Mar 10, 2020 8:51:09 GMT -8
Hi Peter; Yes, I think so, this is in a 25' x 30' high ceiling, only marginally insulated auto shop.Where the large doors will be opened from time to time. My bell was sized to be apx 6" batch size (its currently an 8" J tube) , so I expect to be raising the walls higher to capture the extra heat. Might not be enough, my friend. A 6" batchrocket system is able to serve 5.3 m² (57 sq ft) of ISA, an 8" system 9.4 m² (101 sq ft). That's quite a lot more, somewhere that 44 sq ft need to be found. Otherwise just calculate what maximum sized bell you could build and scale the core accordingly. It might turn out a 7" system is a better fit in your situation.
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Post by belgiangulch on Mar 10, 2020 13:54:10 GMT -8
Thank You Peter! This is why I post. Feedback on my hair brained idea's! I'll be doing some measuring , maybe a 7" would be better.
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Post by belgiangulch on Mar 11, 2020 14:00:02 GMT -8
Hi Peter; A few questions. What would the dimensions of the 7" floor channel be? Would the 1.75 x 1.75 x 1/8" that was to small for the 8" work for a 7"?
You may not remember, but my shop stove uses a 55 gal barrel on it. I have the head room to add a second. If my buddy and I can do math a second barrel added on my first would add 21' of isa?
I'm hoping if I were to add a second barrel and bring my bell walls up another foot, I may reach 7" isa size.
One last question, Is it a problem, if the riser is taller than the size listed in the batch chart
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Post by peterberg on Mar 12, 2020 7:20:17 GMT -8
What would the dimensions of the 7" floor channel be? That would be 5% of a round riser's csa. In your case, 1.4" square duct (inside) would be just right. Would the 1.75 x 1.75 x 1/8" that was to small for the 8" work for a 7"? That duct would be 1.5" square inside. It's ever so slightly oversized but certainly would work, yes. You may not remember, but my shop stove uses a 55 gal barrel on it. I have the head room to add a second. If my buddy and I can do math a second barrel added on my first would add 21' of isa? Yes, a barrel is a bit better in extracting heat but in practise you say it's the same as compared to brick. One last question, Is it a problem, if the riser is taller than the size listed in the batch chart Good question. As a guess: a couple of inches won't make any difference but a foot is overdone.
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Post by belgiangulch on Mar 12, 2020 8:22:36 GMT -8
Thank You very much Peter! Really appreciate your monitoring the forums and quickly responding to share your knowledge with the rest of us.
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