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Post by daniel on Dec 24, 2015 12:00:05 GMT -8
Seems like you have a lot of mass after the barrell but inside the half barrells have a CSA much larger than the flue of a bench where heated gases have some room to stay above the lower flow. I did not know this kind of arrangement would work as a bell. Cool
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Post by dustinmattison on Dec 25, 2015 18:57:02 GMT -8
I would choose the bell in bench method if I could start over. But I already built my bench with a flue design. I will send pictures later this week.
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Post by dustinmattison on Jan 3, 2016 21:14:02 GMT -8
peterberg or anyone else who can help me, I don't know what to do about this. This is a 6 inch batchbox with a bell and 8 inch ducting. I built a bell with an ISA of about 2.84 meters squared. (a 1.2 meter tall, 60 cm wide barrel with another 20 cm height added below) Questions: 1. Can you take a look at my pictures. Does this design make sense? 2. Is it ok that the incoming gasses are 20 cm higher than the exiting gasses in the bell? 3. I did a test run and several problems. I didn't install a chimney yet, so that may be one factor. After the gasses pass through the bell they are run through 12 feet of horizontal bench ducting. 4. Also, the test run was done when everything was still wet. My wood may not be perfectly dry, but I don't know how to check if the wood is dry. Problems: 1. The smoke comes into the house, mostly through the p-channel. (this mostly happens when I fill the box completely) Also, I need to fix the p-channel overhang. Right now it is too short and the p-channel doesn't reach far enough down (2 cm too short) 2. The bell does not get very hot, I can place my hand on the bell and it won't burn. It seems to heat very slow and I don't know where all the heat went. 3. The ducting and bell is full of black grease already. There is a lot of smoke. Is this ok? What is the cause? I put a cap on the top of the opening shown below....
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Post by daniel on Jan 3, 2016 23:46:03 GMT -8
Hi,
From what I see in the pictures and the descriptions of the problems it seems like there is not enough draft therefore back smoke, not proper combustion, soot deposit resulting from incomplete burn etc. I would first put a proper chimney in place with at least 8" diameter. The piping should have been system size or 6". I think after you put the chimney it will draw properly.
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Post by dustinmattison on Jan 4, 2016 0:28:00 GMT -8
daniel What would be the advantage of putting the barrel over the heat riser, instead of on the side like I show above in the picture? Originally, I had the barrel over the heat riser and no bell, just ducting. But there wasn't much draft. After I created the bell model above it improved, but now the heat in the bell isn't that hot. If I keep the current model, I might expand the size of the bell and instead of having the ducting through 12 feet of bench, just exit straight to the chimney. I haven't seen much result so far in heating the bench with ducting. It might be best to just focus on having a good bell that also has thermal mass so it can function as a heated "sofa" to lean on.
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Post by daniel on Jan 4, 2016 0:42:49 GMT -8
You said this is a batchbox, from the pictures I see that it looks like a rocket heater with top loading also I do not see the P-channel.
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
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Post by morticcio on Jan 4, 2016 1:42:11 GMT -8
Firstly, I'm struggling to see how this worked as a J-tube RMH let alone as a batch box bell. Does the chimney exit above the riser? Where do you feed the wood? Can you label parts of the stove to clarify this please.
Here are my observations...
- I'll second what Daniel said - it will not work efficiently without a decent chimney, although if it is a 6" system you would ideally want a 6" chimney, not 8".
- You need dry fuel - below 20%. You can buy a moisture detector from ebay or Amazon
- You never completely fill a batch box with wood
- Stick to either a bell or ducting
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Post by daniel on Jan 4, 2016 2:05:29 GMT -8
Hi Dustin,
Putting the barrel over the riser and keeping about a 2" space above the riser (see details about rocket barrel spacing around riser) will create an expansion of gases which will push the gases through your bench. From what I see you arrangement does not work as a bell. To have a bell you need about 12" or so (see forum) above the riser which will work as a bell. You already have a flue system so putting a bell to a flue system will not in that configuration. What I would do in your situation since you have the 8" piping I would try to install a 8" chimney which will create a good draft and change the firebox to either a rocket or a batchbox.
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Post by peterberg on Jan 4, 2016 2:17:20 GMT -8
According to the pictures, this isn't a batch box nor a proper J-tube. The bare stovepipe could be the riser and the slightly bigger vessel to the right of it could be the bell. This thing won't burn properly because you messed up the whole thing adequately, leaving out most of the essentials.
1. There's no insulated riser. 2. The "barrel" can't be placed over the "riser" because there's not enough room. 3. A batch box need to have a front loading opening and a closed top. 4. A J-tube need to have a consistent cross section area through the core. 5. A bell need to have the feed and exhaust low in the sides to qualify as such, not from the top down. 6. A bell need to have at least a cross section area of 4 times the riser, preferably more.
So, please decide what to build and keep to the checked and approved constructions.
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Post by dustinmattison on Jan 4, 2016 2:41:33 GMT -8
morticcio and daniel peterberg PLAN A: Barrel and ductingHere is a picture of the 6 inch batchbox before I installed the door. You can see the barrel on top of the heat riser in my original configuration. That is when I tried to route through 8-inch ducting, about 25 feet long with about 6 turns. Considering the number of turns and the length of the ducting I thought that could have been the reason for not enough draft. But now I am not sure. I will call this PLAN A. Under this plan, the chimney exit is behind the barrel above the heat riser. It goes outside and above the roof about 8 feet. 8 inch chimney. When I tested this PLAN A it did not have much draft. Is it a problem if the barrel leaves no space on one side? The reason for this is because it is too close to the wall, so I have to squeeze the barrel in and leave the side opposite the wall for the gasses to flow through and down. And here is PLAN B: Bell next to heat riser.
This is a bell next to the heat riser. There is ducting that channels the gasses from the heat riser down below the bell. Chimney Question: I already bought 8 inch Chimney tubing. Could I just add a short 6 inch tube at the top of the chimney? Other questions: Since I have been experimenting with both Plan A and B, I guess I should keep testing both plans to see which one will ultimately work. So my question is can I put the barrel over the heat riser and then build a bell next to it, or is it better to set up a Bell system like my PLAN B? To answer peterberg's questions: According to the pictures, this isn't a batch box nor a proper J-tube. The bare stovepipe could be the riser and the slightly bigger vessel to the right of it could be the bell. This thing won't burn properly because you messed up the whole thing adequately, leaving out most of the essentials. 1. There's no insulated riser. (the heat riser is on the right. I built it with perlite and refractory, see pictures here:)
2. The "barrel" can't be placed over the "riser" because there's not enough room. (Why isn't there enough room? The riser is about 80 cm high, and the barrel is 90 cm high)
3. A batch box need to have a front loading opening and a closed top. (see pictures above, I do have that) 4. A J-tube need to have a consistent cross section area through the core. (this isn't a J tube, I changed my original design) 5. A bell need to have the feed and exhaust low in the sides to qualify as such, not from the top down. (I do have that don't I? See new pics above)6. A bell need to have at least a cross section area of 4 times the riser, preferably more. (this I am still trying to figure out how to calculate. I just used the barrel I had available for testing purposes. Do you think it is too small?)
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morticcio
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Post by morticcio on Jan 4, 2016 3:13:06 GMT -8
It seems to me you have got confused over the design of both and are trying to mix and match to suit.
As per what Peter said, choose either a J-tube or batch box and stick with a tried and tested design. If you follow some simple rules it will work.
Either way the firebox looks too close to the wall for both types. This probably isn't what you want to hear but I would rip it all out and start again.
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morticcio
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Post by morticcio on Jan 4, 2016 3:22:11 GMT -8
The top of the riser on any rocket needs to be open. Why have you got a 180° bend on it???
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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 Jan 4, 2016 3:39:54 GMT -8
You've converted it from a J-tube to a batch box. Could you confirm you have a vertical 'letter box' between the batch box and riser?
A good example of a vertical 'letter box' is one in this picture of an experimental stove from Andrea (indipendentenergy). The photo also shows what the top of a riser should look like - no bends. Obviously it would have a barrel or a bell enclosed around it.
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Post by dustinmattison on Jan 4, 2016 3:52:12 GMT -8
morticcio I don't understand what is wrong with the batchbox being close to wall? What is the reason it can't be close to a wall? The wall is made of clay and sand, not flammable. I haven't converted from a J-tube. I built from scratch a new batchbox according to the design specs in this forum, including the vertical letter box. The heat riser is round. I made it from refractory and perlite using a mold. Regarding the 180 degree bend at the top of the riser, I thought I saw diagrams on this forum where the bell design worked like this. So this is a problem? If so, then that means I have to put a barrel over the heat riser instead, right? Does the gap between the heat riser and barrel have to be equal all around, or can I have most of the space on one side of the barrel? What is the minimum space you need at any point between the barrel and heat riser? My barrel diameter gives me 5 inches of space all around, not considering the wall which will probably only leave me 2 or 3 inches on one side.
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morticcio
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Post by morticcio on Jan 4, 2016 5:13:03 GMT -8
In the photos it looks close too the wall. You also used the phrase 'so I have to squeeze the barrel in'. If you think there is adequate clearance for either a barrel or a bell then ignore what I said.
If the batch box is built to design specs then it should work providing the rules for a bell or a barrel are observed (see what Peter said above) and there is an adequate chimney. Additionally for ducting, this includes the diameter & length of the duct and number of bends.
I don't ever recall seeing a 180° bend on the top of the riser. There has been an insulated 90° bend on another forum. The bend needs to be removed.
The barrel can sit slightly offset.
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