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Post by thickstrings on Sept 17, 2014 10:54:11 GMT -8
I am sure a device like that would be useful...That being said, a 4" burn chamber is small. Bundles of sticks would most probably have to be "jiggled" from time to time, or you'll screw with the oxygen/fuel mix, which leads to smoking and up burning of the fuel......ask me how I know.... I suppose it would work better in a larger system....THAT being said, if you have the mass in a larger system, then, a loading or 3 and the mass is hot for a while..... eliminating the need for a mechanical loader...I have been fooling around with a portable 4" for a while now and am still trying to dial it in...My next, and permanent one will no doubt be a 8"....as the 4"ers are a bit finicky. But, what the heck...try it!
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joseph
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Post by joseph on Sept 17, 2014 14:40:25 GMT -8
I am sure a device like that would be useful...That being said, a 4" burn chamber is small. Bundles of sticks would most probably have to be "jiggled" from time to time, or you'll screw with the oxygen/fuel mix, which leads to smoking and up burning of the fuel......ask me how I know.... I suppose it would work better in a larger system....THAT being said, if you have the mass in a larger system, then, a loading or 3 and the mass is hot for a while..... eliminating the need for a mechanical loader...I have been fooling around with a portable 4" for a while now and am still trying to dial it in...My next, and permanent one will no doubt be a 8"....as the 4"ers are a bit finicky. But, what the heck...try it! I think you are correct on the problems with a 4 inch system burning tree wood. I checked my notes and I saw that the stove itself actually had a 6 inch burn chamber. (I edited the OP to say "or 6 inch"). The maximum diameter of the log in the loader is 4 inches. I am trying to emulate a residential furnace, of the type used in standard homes in the USA. I am not looking for a mass heater. By the way, if you are having problems with a 4 inch system, a 6 inch may be better than an 8 inch; an 8 inch is pretty big. - joe
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morticcio
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"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Sept 17, 2014 15:52:56 GMT -8
The magazine would hold 12 logs, each up to 4 inches (10 cm) in diameter, in separate compartments. I could make it hold more, or bigger, but then the whole unit would be larger, and take up more room. The principle of operation would work on a larger model. Each "log" could actually be a bundle of sticks, or two smaller logs. What I need right now is not help in mechanical engineering but for people to answer two basic questions: 1) Would you find such a device useful? 2) In your experience with a "J" tube, assuming that there are already coals and the system is up to temperature, how does it perform for burning logs? Or does it only work well for burning sticks?
- joe In answer to your questions: 1) No 2) On my 8" system it worked best with 'sticks' up to 2" diameter. I occasionally had to jiggle them round to stop creep etc.
From your experience with a "J" tube, did it work well with a 4" log or bundle being dropped in blindly?
At the risk of sounding negative, your plan sounds like it is all theory and no practice.
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joseph
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Post by joseph on Sept 17, 2014 16:42:53 GMT -8
.... 2) In your experience with a "J" tube, assuming that there are already coals and the system is up to temperature, how does it perform for burning logs? Or does it only work well for burning sticks?
- joe ....
From your experience with a "J" tube, did it work well with a 4" log or bundle being dropped in blindly?
At the risk of sounding negative, your plan sounds like it is all theory and no practice.
I had mixed results, depending on the quality of the wood. But the chamber was not well-insulated and such, so there may have been other factors involved. It was just an experimental set-up, not a permanent installation. I have an Amish wood cookstove that I use to heat my house, but I do not have much experience with rocket stoves. That is why I asked question #2. I do, however, understand mechanics and can build things. - joe
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Post by DCish on Sept 17, 2014 19:06:39 GMT -8
In seeking to emulate a residential furnace with no mass, have you thought about the issue of regulating heat output? A residential furnace runs intermittently based on demand as regulated by a thermostat. A rocket mass heater's output is regulated by the length of the burn used to store heat in the thermal mass before the fire is allowed to burn out. How would your system accomplish heat output regulation?
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joseph
Junior Member
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Post by joseph on Sept 18, 2014 6:04:00 GMT -8
In seeking to emulate a residential furnace with no mass, have you thought about the issue of regulating heat output? A residential furnace runs intermittently based on demand as regulated by a thermostat. A rocket mass heater's output is regulated by the length of the burn used to store heat in the thermal mass before the fire is allowed to burn out. How would your system accomplish heat output regulation? There are always compromises. With a conventional wood stove, there is no regulation at all, except what is done manually. If you want it to be warm for your family at 7:00 am, you must put more wood in the stove at 5:30 am. If it gets too hot, you cut off the air, and make lots of smoke. There is also no way of evenly distributing the heat all around the house, for example, into the bathrooms. A modern gas furnace with multiple zones and programmable thermostats, of course, has none of these problems. I am proposing an improvement to the wood stove. As such, it must be compared to other wood stoves. A residential furnace typically uses one of two ways to distribute the heat: forced air ducts, or hot water baseboard radiators. One way in which the heat from a constantly-burning wood furnace could be regulated is to control the fans or pumps that distribute the heat. Another way is that the loader itself could be regulated by a thermostat. The thermostat would be mounted somewhere on the wall, and a 24 volt solenoid attached to a certain part of the loading mechanism, stopping its operation until the thermostat calls for heat. (This assumes that the firebox will still contain enough hot coals to restart the fire when the new wood is finally added.) My original design was for the loader to powered by a wind-up mechanism, without electricity. However, if you start talking about regulation, then you are getting fancy, so I can use electric thermostats and solenoids. - joe
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joel
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Post by joel on Oct 1, 2014 22:26:23 GMT -8
Joe,
I can tell you that, a 4.5" j tube that is up to temp will burn 2"x4"x5" lumber cut offs just fine.
As for usefullness: not particularly useful.
although I would integrate an ultrasonic sensor $20, infrared sensor $1, large transistor/relay, and an arduino $40 to trigger the magazine.
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joseph
Junior Member
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Post by joseph on Oct 2, 2014 8:32:58 GMT -8
Joe, I can tell you that, a 4.5" j tube that is up to temp will burn 2"x4"x5" lumber cut offs just fine. As for usefullness: not particularly useful. although I would integrate an ultrasonic sensor $20, infrared sensor $1, large transistor/relay, and an arduino $40 to trigger the magazine. >> lumber cut offs << Yes, it is easy to burn carpenter's lumber. Most of the the tests I have seen use wood shop scraps. Tree wood is more difficult to burn, but is more available in rural areas. >> although I would integrate an ultrasonic sensor $20, infrared sensor $1, large transistor/relay, and an arduino $40 to trigger the magazine. << Using electronic sensors and controls seems like an obvious solution, and that could be added if the mechanical controls were not adequate. Certainly some of the more sophisticated pellet and corn burning stoves have a host of electronics in them. But I doubt you would need something like an arduino; you could probably pull it off with some clever engineering and the classic 555 timer. I am actually more impressed with a mechanical solution, like the Clarry Pellet Stove, than I am with something with augers, ignitors, sensors and microprocessor controls. >> not particularly useful. << Is that because it is a rocket stove, and you don't intend it to burn all night? What if this was applied to some other stove, like a pellet stove that used logs instead of pellets? - joe
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Post by Donkey on Oct 2, 2014 19:39:36 GMT -8
What I need right now is not help in mechanical engineering but for people to answer two basic questions: 1) Would you find such a device useful? 2) In your experience with a "J" tube, assuming that there are already coals and the system is up to temperature, how does it perform for burning logs? Or does it only work well for burning sticks?
- joe 1) Maybe, though I don't use ANY of my stoves in this way. 2) In my experience, you can feed in a "log" if you also feed in a little stick wood with it to keep the flame going actively. I think little bundles of sticks are going to work better. It seems (to me) a mistake to loose the mass... IF the purpose is to not take up a bunch of room in the house, or that you want to utilise a pre-existing central air system or something like that, then let me entertain you with a slightly different thought.. Firstly, storing heat in air is about as inefficient as it gets. Air is an insulator and is TERRIBLE at storage. It can be convenient for pumping around, but otherwise, it stinks. How about instead of a continuous-fire system and all of the difficulties that come with it, using a batch fire system that heats an external (to the house), well insulated mass to a ridiculously high temperature. The mass would be outside, in the fire-shed and could be alternately heated with solar, etc. You would then pump air through that mass and into the central air distribution system of the house. In this way, all of the intelligence of the system would be in the heat distribution system, coupled with the mass; not in trying to feed a fire continuously with robotics and deal with irregular bundles, etc.. It can play double duty with solar heat, reducing the amount of wood you use, stacking functions, bringing down costs, have fewer moving parts, less likely to experience interference by Murphy's laws, and all that. My $.02
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joseph
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Post by joseph on Oct 3, 2014 16:48:47 GMT -8
... It seems (to me) a mistake to loose the mass... IF the purpose is to not take up a bunch of room in the house, or that you want to utilise a pre-existing central air system or something like that, then let me entertain you with a slightly different thought.. ... Firstly, storing heat in air is about as inefficient as it gets. Air is an insulator and is TERRIBLE at storage. It can be convenient for pumping around, but otherwise, it stinks. ... It would be used to heat water for baseboard heat to distribute the heat to different rooms. The furnace would run all night. If a forced air system was used instead of water, the air would not hold the heat, only distribute it - just like a standard gas furnace. - joe
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Post by aparker on Oct 3, 2014 19:19:43 GMT -8
Ok, then, take Donkey's last paragraph and replace "air" with "water".
When I was contemplating putting in a solar system, the plans I reviewed used an insulated storage tank which could be heated either by the solar panels or a furnace. The hydronic system's closed loop was passed through the tank. I was planning on using a water to air heat exchanger in a forced air system, some spot in-floor heating and baseboards.
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Post by aparker on Oct 3, 2014 19:34:45 GMT -8
The idea of an automatic feed intrigues me. I think it could be done mechanically -- no electronics. If you put together standardized bundles of twigs, branches or split wood, bales of biomass, or briquettes, I think it ought to work, though perhaps not perfectly. (Some of the first hay bale machines were to make small bales for fuel.)
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joseph
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Post by joseph on Oct 4, 2014 5:50:17 GMT -8
Ok, then, take Donkey's last paragraph and replace "air" with "water". When I was contemplating putting in a solar system, the plans I reviewed used an insulated storage tank which could be heated either by the solar panels or a furnace. The hydronic system's closed loop was passed through the tank. I was planning on using a water to air heat exchanger in a forced air system, some spot in-floor heating and baseboards. .... The idea of an automatic feed intrigues me. I think it could be done mechanically -- no electronics. If you put together standardized bundles of twigs, branches or split wood, bales of biomass, or briquettes, I think it ought to work, though perhaps not perfectly. (Some of the first hay bale machines were to make small bales for fuel.) No, I am not trying to store heat at all. I am just trying to make a rocket stove act similar to a conventional furnace by using water in baseboard radiators to distribute heat to various rooms. Keep in mind that when I am talking about an automatic feeder, I mean a device that mechanically loads the wood into the firebox - not something where the wood is stacked up and slides down some kind of chute. - joe
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Post by aparker on Oct 4, 2014 10:36:28 GMT -8
Furnaces do not run continuously. They run in cycles (or batches, to make the relationship with wood stoves).
Using a chute would be the easiest solution, but there is the danger of the fuel catching fire. Preparing uniform charges would be the easiest way to design and implement an automatic feeder, whether you are using pellets or hay bales.
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joseph
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Post by joseph on Oct 4, 2014 15:51:29 GMT -8
Furnaces do not run continuously. They run in cycles (or batches, to make the relationship with wood stoves). Using a chute would be the easiest solution, but there is the danger of the fuel catching fire. Preparing uniform charges would be the easiest way to design and implement an automatic feeder, whether you are using pellets or hay bales. I addressed your first point in the Sept 18 post above, and the second point in the Sept 14 post. Have you read them? - joe
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