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Post by craypappy on Jan 15, 2018 9:10:24 GMT -8
I’ve recently finished an 8” batchbox. Its performing very well so far. I built the door with a glass panel so I can view the fire. Problem is the top half of the glass keeps getting blackened with soot. Is this typical for a batchbox? Or is this a sign that something’s not right?
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Post by craypappy on Jan 12, 2018 17:04:47 GMT -8
Thanks Peter. Will do. I do have a CO detector that has not alarmed (yet).
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Post by craypappy on Jan 12, 2018 12:33:36 GMT -8
I finally completed my 8” batchbox and fired it up a few days ago. Yay!!
Bell is 2 layers of brick laid flat. Upper part (starting just below the top of riser) of the inner layer is firebrick to withstand the highest heat. Very pleased with its performance so far.
Issues (minor I hope): 1. A vertical crack developed almost immediately near the top of one wall of the bell. Crosses at least 6 courses of brick. Crack is widest at the top, probably 2mm. I’m presuming this crack developed from the inner “ring” of bricks becoming hotter and expanding more than the outer bricks. Should I have included an expansion joint? Do I need to be concerned about this crack? It is my understanding that there is negative pressure inside the bell, so no danger of noxious gasses leaking out through this crack into my house. Correct?
2. Somewhat unpleasant smells are venting from heater for 2-3 hours following firing. I’m presuming this is normal from the new bricks and other materials being fired for the first time and will subside over time. True?
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Post by craypappy on Nov 5, 2017 5:22:11 GMT -8
Thanks for input, everyone. I believe I will leave it as is.
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Post by craypappy on Oct 31, 2017 18:16:05 GMT -8
Situation: I am nearing completion of an 8” batchbox. My riser height is 10x base. My bell cap is 12” above the top of the riser.
a. Peter recommends a 12” minimum gap above the top of the riser, and comments that more is better. b. Recommended riser height is 8-10x base. I’m assuming that maximum riser height (10x base) is better than minimum (8x base).
Question: which “more is better” recommendation (a or b) dominates?
I could easily shorten the riser to 8x base which would increase the gap above the riser to almost 24”. Or split the difference and go 9x base and 18” gap. Or leave it as is.
Which would give the best predicted performance?
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Post by craypappy on Sept 16, 2017 14:59:54 GMT -8
Thanks so much for info!! I believe I'm going to love ceramic fiber board!
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Post by craypappy on Sept 14, 2017 14:03:56 GMT -8
Very cool. Thanks so much for great video. Makes me ponder other uses, including the following.
Peter recommends putting insulation over the top of a slab of casted refractory concrete when capping the bell. I'm wondering if one could do better with having the insulation beneath the slab instead?
Questions: 1. Is ceramic fiber board strong enough to reliably support itself across a 2+ foot span? 2. If so, would the natural compressibility of the ceramic fiber board form a natural seal around the perimeter from the weight of the heavy slab? 3. Is the insulation from the ceramic fiber board sufficient to permit the use of regular reinforced concrete for the slab instead of refractory?
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Post by craypappy on Sept 13, 2017 16:39:30 GMT -8
What material is best to use for capping the top of the bell - refractory castable or firebrick? The outer measurements are 610mm x 1150mm. If I use refractory castable - what is the minimum thickness and the approx. area a 25kg bag of 1600C castable will cover for that thickness so I can work out how many bags I'll need? I can source 610mm x 230mm x 76mm firebrick but it will work out expensive! Is the roof of the bell above the heat riser? Or are you utilizing the classic "barrel" heat exchange above the riser channeling down to the bell? If you're using the latter design, simple materials will suffice - I used classic cob supported with corrugated steel. Speaking for myself, roof of bell is above the riser. I'm planning to use castable refractory. Will probably go with 80mm thick slab for peace of mind (Peter above says 50mm is sufficient). I would feel even better if I could add some support underneath but what will withstand the heat? My fear is if slab fails and falls into void, my house will burn down. Am I being paranoid?
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Post by craypappy on Sept 7, 2017 12:47:15 GMT -8
The 1600C is probably over-specced. You need two slabs to span that stove, both can rest on three sides that way. Minumum thickness 50 mm, cover with isulation. How wide will 50mm thickness safely span across top of bell? Wondering how to avoid disaster of it fails? What type of insulation do you recommend? I see this is an old post. Have recommendations changed?
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