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Post by pinhead on Jan 31, 2013 7:15:16 GMT -8
Very interesting, indeed.
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Post by pinhead on Jan 31, 2013 7:00:49 GMT -8
Very interesting, indeed.
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Post by pinhead on Jan 25, 2013 13:42:11 GMT -8
One question: what happens when at one time it burns (smokeless) only at the bottom of heat riser and then all of a sudden the fire is in the whole heat riser and the flame looks much softer, different than below?! I've noticed the same thing with "normal" rocket stoves when burning everything from oak 2x4s to cedar to plastic and oil. From what I have been able to ascertain, before the "burning riser" phase, there are still traces of unburnt combustibles leaving the riser. Once the temperature inside the stack rises to what is required to burn those chemicals, they all-at-once burst into flames. This theory is strengthened by the observation that the better-insulated the riser is, the sooner this "burning riser" phase is reached. It would also be supported by Petersburg's measurements, with the temperature being higher at the top of the riser than the bottom during this phase, as more chemicals are burning and producing heat within the riser. Firefighters call it flashover. I suspect it would be, more specifically, a hot rich flashover.
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Post by pinhead on Jan 24, 2013 13:54:39 GMT -8
You can say, oh well, it's a slightly larger problem, I am able to solve that with a drain pipe of some sort and a water slot. And there you are wrong, when the gases are cooled down to condensation point, the chimney will get wet and the water will run down. That will eventually cool the chimney down to the same temperature as the outside air and the draw will stall. Smoke will come out everywhere. Been there, done that and believe me, I wasn't glad. Did this happen with an insulated chimney? I installed a 6" RMH in my uninsulated, very "leaky" shop. In fact, the chimney/stack is in the northeast corner, right next to a 6"x6" hole. Over Christmas break when I spent a lot of time in the shop, that hole in the wall let in a lot of cold air, so much so that there were icicles forming on the side of the chimney. The moisture was from condensation that was dripping out of the elbow where the chimney went through the wall. I haven't had any trouble with a stalled draft...
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Post by pinhead on Jan 23, 2013 6:36:42 GMT -8
If you want to take this a further, check out Earthships.
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Post by pinhead on Jan 21, 2013 13:26:30 GMT -8
To get the pics to imbed, get rid of the "S" in https://
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Post by pinhead on Jan 21, 2013 8:45:19 GMT -8
What are you using for insulation? If you're using some type of "loose-fill" insulation, you'll find that when the internal steel burns out, you'll have to rebuild the whole works. Notice, I said "when" and not "if." Metal will burn out inside a properly-functioning rocket stove.
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Post by pinhead on Jan 11, 2013 6:03:25 GMT -8
Pinhead, I see where there might be some confusion. On that top view, it is refractory that is lining the inside of the brick, not insulation. I see. I guess I don't completely understand the nature of refractories, as I assumed they were somewhat insulative. Donkey, I said octagon but I meant pentagon. ;D I've been following the horizontal-feed rockets very closely and am very familiar with their layout. You and I are in complete agreement.
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Post by pinhead on Jan 10, 2013 13:32:08 GMT -8
Forgive me if this has already been figured out... But wouldn't insulation on the inside of the pentagon reduce and eventually eliminate the temperature differential between the inside of the riser and the pentagon, thus stalling the draft?
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Post by pinhead on Jan 10, 2013 6:16:46 GMT -8
Are you going to fill that with insulation or is the pentagon replacing what would be the barrel in a typical RMH?
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Post by pinhead on Jan 8, 2013 9:34:08 GMT -8
You've probably got a "triple wall chimney pipe."
It will work great... For a while. The stainless will burn out in the elevated temperatures and low CO levels found inside a Rocket Stove. It'll last longer than a normal sheet metal heat riser, though it'll still eventually burn out -- and those triple wall chimney pipes ain't cheap!
As for your barrel height question, I personally prefer to have a quite large gap between the heat riser and the barrel -- there's a 12" gap in my rocket. But a 2.5' riser may be too short depending your chimney temps and height.
For some reason I can't remember the riser height to burn tunnel length ratio, I believe it's 2.5:1 but don't quote me on it. If that's the case, you can only have a 1' burn tunnel which severely limits your barrel diameter choices...
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Post by pinhead on Jan 8, 2013 8:39:39 GMT -8
I'm not 100% sure on their lifespan since my 3-year-old casting is still being used. You don't have to cast the heat riser with the expensive cement since it won't be bumped and/or moved around when loading and cleaning. For the riser I used clay/sand/ash (8" duct surrounding 6" duct) and then pure perlite around that (6 inches total of insulation around 6" of riser). The eight-inch duct holding the heat riser together should last virtually indefinitely. That way when the heat riser eventually burns away, the clay/sand/ash will stay in place and I still get the superior insulation of pure perlite on the outside of the clay/ash riser. So you do add the cement to the burn tunnel to add stability? Yes.
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Post by pinhead on Jan 7, 2013 12:14:49 GMT -8
I'm using a few steel 5-gallon buckets, about 12" diameter, stacked on top of each other. A 12" flue pipe would be perfectly sufficient. Anything would work as long as it won't melt from the heat coming from the stove (probably couldn't use thin aluminum). This outer "shell" won't be exposed to flame, though, so the longevity isn't suspect like the inside of the core.
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Post by pinhead on Jan 7, 2013 9:36:20 GMT -8
I'm not 100% sure on their lifespan since my 3-year-old casting is still being used.
You don't have to cast the heat riser with the expensive cement since it won't be bumped and/or moved around when loading and cleaning.
For the riser I used clay/sand/ash (8" duct surrounding 6" duct) and then pure perlite around that (6 inches total of insulation around 6" of riser). The eight-inch duct holding the heat riser together should last virtually indefinitely.
That way when the heat riser eventually burns away, the clay/sand/ash will stay in place and I still get the superior insulation of pure perlite on the outside of the clay/ash riser.
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Post by pinhead on Jan 7, 2013 7:08:27 GMT -8
By "burn box" do you mean a Peter-style horizontal feed or are you referring to the "burn tunnel" in the typical J-tube Rocket Stove?
I only have experience thus far with the latter. I cast them both. The burn tunnel will burn out more quickly than the heat riser in my experience, though the bottom quarter to third of the riser will eventually burn out as well.
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