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Post by peterberg on Dec 22, 2014 1:21:29 GMT -8
Certainly on most rocket stoves the first bell, in the barrel, is smaller than the second bell, the bench... This isn't correct I'm afraid. The barrel is not a true bell because the inlet and exhaust aren't both close to the bottom. Most rocket mass heaters does sport a round duct in the bench, all the gases are following the same path. In that same bench there isn't a larger space where the gases are allowed to stratify, the most significant hallmark of a bell. So, neither the barrel nor the bench qualifies as a bell...
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Post by patamos on Dec 22, 2014 11:24:25 GMT -8
Yes. Best to locate the bypass exit about 1/2 way down the side wall of the downdraft chamber (technically the barrel outside the heat riser is not a bell). And then the exit from the (actual) bell located somewhere close below that so the tie in is simple.
If you are doing two bells (with all input and exhaust ports set low in the chambers) the second bell is smaller because there is less heat available to extract. Ultimately, you do not want to stall the process with cool gasses.
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Post by pinhead on Dec 22, 2014 12:55:53 GMT -8
Certainly on most rocket stoves the first bell, in the barrel, is smaller than the second bell, the bench... This isn't correct I'm afraid. The barrel is not a true bell because the inlet and exhaust aren't both close to the bottom. Most rocket mass heaters does sport a round duct in the bench, all the gases are following the same path. In that same bench there isn't a larger space where the gases are allowed to stratify, the most significant hallmark of a bell. So, neither the barrel nor the bench qualifies as a bell... Shouldn't the top your double barrel tower be considered a bell? It, too, has a low inlet and outlet - the "floor" being defined by the top of the riser.
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Post by peterberg on Dec 22, 2014 13:47:50 GMT -8
Pin, Yes, you could see it this way, you could be right. An RMH "by the book" doesn't have much room above the riser. Both my workshop tower and the 8" batch box in Montana does sport a bit more than a whole empty barrel as the top gap. But... on the other hand, I've seen the wildly turbulent flame fountain inside it. Not a chance stratisfying would occur in that when running flat out.
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Post by wrekinwanderer on Dec 27, 2014 4:53:30 GMT -8
Thank you for the clarifications regarding bells.
A question: is the ISA of the barrel, the downdraft chamber, included in calculations to measure the total ISA?
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Post by peterberg on Dec 27, 2014 5:22:48 GMT -8
A question: is the ISA of the barrel, the downdraft chamber, included in calculations to measure the total ISA? In the sense that it is indeed a heat extractor, the answer is yes. I would regard the barrel as a steel bell, a bench built as a bell as masonry.
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Post by daniel on Oct 11, 2015 10:40:51 GMT -8
Certainly on most rocket stoves the first bell, in the barrel, is smaller than the second bell, the bench... This isn't correct I'm afraid. The barrel is not a true bell because the inlet and exhaust aren't both close to the bottom. Most rocket mass heaters does sport a round duct in the bench, all the gases are following the same path. In that same bench there isn't a larger space where the gases are allowed to stratify, the most significant hallmark of a bell. So, neither the barrel nor the bench qualifies as a bell...
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Post by daniel on Oct 11, 2015 10:56:31 GMT -8
Certainly on most rocket stoves the first bell, in the barrel, is smaller than the second bell, the bench... This isn't correct I'm afraid. The barrel is not a true bell because the inlet and exhaust aren't both close to the bottom. Most rocket mass heaters does sport a round duct in the bench, all the gases are following the same path. In that same bench there isn't a larger space where the gases are allowed to stratify, the most significant hallmark of a bell. So, neither the barrel nor the bench qualifies as a bell...
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Post by daniel on Oct 11, 2015 10:56:41 GMT -8
Hi,
I built the box and the riser but now since I started reading more about the bells I am more confused and worried not to make a mistake. I don't have ver much space for the second bell but I do want to ad one at some point if not now. Basically the first bell could be only over the riser or covering the whole batchbox . I could make it round or square. Round would have about 6.2 square meters 7 with the top. For an 8" system I would want to ad a second bell some time to make it more efficient. Not sure if this bell is too big or is this a good thing. I was thinking that by making the bell all the way around to the firebox door would give less chances of gases escaping rather then coming with the wall butt jointed against the firebox. Please your advice
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Post by daniel on Oct 12, 2015 5:00:11 GMT -8
Today I lit up a small fire in the batch box, it does not have a bell yet so I just wanted to dry it up a little since the insulation in the riser was a very wet mixture. It draws like crazy, This encourage me. It buys me more time to figure out how am i going to do the bells.
My space for the second bell is a little awkard I don't want to make a mistake on it, I also want to give the heater a nice look, an arhitectural design this is why I have to think of its shape.
So far I had these ideas: shaped like a snail from the first to the second bell a descending spiral, or two cylinders.
Does anbody know if it is better to put the batchbox altoghether into the bell or surround only the riser?
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Post by peterberg on Oct 12, 2015 5:28:38 GMT -8
My preference since a year: Just a single bell surroundeng the whole core. Despite the fact this isn't a true bell construction due to being fed halfway or higher it will be quite uniform in temperature and it extract heat very well. I have one at home, not really dry and all but 5.5 square meters turned out to be too much heat extraction. I lowerd the top as much that the ISA became 5 m2 including the ceiling and excluding the floor. The firebox is raised from the floor, the top of it is 3' or 90 cm from the floor level.
No problem with draw at all.
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Post by daniel on Oct 12, 2015 6:09:06 GMT -8
Mine is raised about 1ft from the floor but I have a cleaning door which I wanted to enlarge for the exit. For the moment the heater is exiting directly into the chimney into another outlet 2m high. I was thinking about the one bell solution with one dead end bench which I would love as a design and functionality but I heard that two bells are more efficient, is this always the case?
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Post by daniel on Oct 12, 2015 6:11:10 GMT -8
One more thing, the box is about 2 ft from the chimne wall is it ok for the riser to be off center inside the bell or perhaps better than centered?
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Post by byronc on Oct 13, 2015 2:56:56 GMT -8
My preference since a year: Just a single bell surrounding the whole core. Despite the fact this isn't a true bell construction due to being fed halfway or higher it will be quite uniform in temperature and it extract heat very well. I have one at home, not really dry and all but 5.5 square meters turned out to be too much heat extraction. I lowered the top as much that the ISA became 5 m2 including the ceiling and excluding the floor. The firebox is raised from the floor, the top of it is 3' or 90 cm from the floor level. No problem with draw at all. Sounds very interesting Peter, what is the system size of this latest creation? I like the idea of getting the batch box up off the floor to save one's back, and have been thinking of building a tall narrow "wall" Russian style heater with a batch fire box. What is the outside dimensions of your bell, and is it single wall or double wall brick or barrel(s)?
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Post by daniel on Oct 14, 2015 1:11:44 GMT -8
I have a question whether this would work: if the riser will go into a larger collection area then split down in 4 tubes of system CSA and then collect into a large area where they could exit to the chimney. The top portion should act as a bell for stratification, the tubes give a 5 sq meter of release surface?
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