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Post by bulbius on Dec 29, 2017 1:07:05 GMT -8
Here's a video where I play with the air inlet. When I let enter too much air the turbulence inside the firebox increase significantly and above the threshold a "wall of fire" forms. When I totally close the air inlet the fire is almost extinguished and the firebox fills up of wood gas (it can be dangerous) and when the air enters again it immediately ignites!
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Post by Orange on Dec 29, 2017 12:36:26 GMT -8
that firewall thing is a beast! I didn't know BB can get dangerous  I like the drawings, 1-in-all design, elevated firebox, insulation and the final non-edgy earthly look  couple of Q's if you dont mind: no cooking plate on top of oven? what's your climate? did you think about building the firebox and oven with the 2-3cm firebricks (it would lower the mass)? the glass from the oven is rated for 250C or higher? what is the exit (to the chimney) temp and bench temp? Will you add more ISA? how's the air-concrete holding up, any cracks? any problems with thermal expansion of the steel rods in firebox? |
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Post by bulbius on Dec 31, 2017 4:24:45 GMT -8
that firewall thing is a beast! I didn't know BB can get dangerous I like the drawings, 1-in-all design, elevated firebox, insulation and the final non-edgy earthly look couple of Q's if you dont mind: no cooking plate on top of oven? what's your climate? did you think about building the firebox and oven with the 2-3cm firebricks (it would lower the mass)? the glass from the oven is rated for 250C or higher? what is the exit (to the chimney) temp and bench temp? Will you add more ISA? how's the air-concrete holding up, any cracks? any problems with thermal expansion of the steel rods in firebox? Thank you Orange! I designed a cooking plate on top of the oven but at the end I decided to not implement it because I was pretty sure that the temperature was not enough and it was not so indispensable to me. Maybe I can drill a little hole in the top and insert a probe to be sure. I live in the center of Italy, Marche area, we have a Mediterranean climate. I preferred to build the firebox with thick firebricks because it should be very strong. It's a big firebox and it must also withstand some accidental bumps from the wood. I don't know how is rated the glass but it has been resisting for two months. I guess the air that enters into the firebox plays an important role in cooling down the glass. For the temperature I'll let you know. Regarding ISA I'm not going to modify this stove while it's working correctly:) I couldn't check the air concrete as they are behind the plaster but I worked with them in other projects and I know that they cracks very badly if subjected to high temperatures I still haven't noticed any problems due to the thermal expansion in the firebox. Only in the plaster around the firebox there are some cracks that almost disappear when the stove cools down and reappear when it becomes hot again. maybe should I put ceramic wool around the firebox to allow thermal expansion to avoid involving the plaster? By the way, I wish you all thinkers, builders and experimenters a magnificent new year!!!!!!  |
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Post by pinhead on Jan 3, 2018 9:46:30 GMT -8
When you closed the primary air inlet and the stove filled with woodgas, it looked like the flame in the riser slowed significantly or stopped altogether. Does your stove not have a P-channel or some other form of tertiary air supply? In a firebox that hot you should be able to virtually stop all firebox combustion by closing down the primary air while the heat riser continues to roar away, provided it is being supplied sufficient pre-heated tertiary air.
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Post by Orange on Jan 3, 2018 10:34:44 GMT -8
bulbius, the air-concrete cracks, but the plaster is holding it. Nice insulation material I plan to use it too. if you notice high temperatures in the chimney than you add more ISA so you save some wood in italy When you closed the primary air inlet and the stove filled with woodgas, it looked like the flame in the riser slowed significantly or stopped altogether. Does your stove not have a P-channel or some other form of tertiary air supply? In a firebox that hot you should be able to virtually stop all firebox combustion by closing down the primary air while the heat riser continues to roar away, provided it is being supplied sufficient pre-heated tertiary air. he has a floor channel. I'm not an expert but this is the best BB video I've seen, in terms of volume of the fire  |
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grga
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Post by grga on Jan 4, 2018 2:10:13 GMT -8
...The space to be heated is large so when it's very cold outside we need to load the stove 3-4 times in a day. The white oven works nicely, after the embers phase it can even reach the full scale at 300° C.
Hi, I would appriciate some more explanation about your white oven. I have similar placement ( donkey32.proboards.com/thread/2307/heater-cast-batchbox-bell-bench?page=4 ) as you but I can reach mux 170C wit a single burn. I did not try two burns one after another... What temperature of the oven can you reach after one single burn from cold or warm heater? My oven is made from INOX and placed over batch box inside the bell. Between the batch box ceiling and oven floor there is 3 cm of cast concrete and 3 cm fire brick (only laid on the batchbox, not glued). Other walls of inox oven face to the bell. I am thinking to place instead 3 cm firebricks some more conductive material like metal. I can not place the oven directly on the batchbox, i need to have 3 cm spacer material in between or air (air is even worse than 3cm bricks). The only difference I see Is that oven is isolated besides its floor and That I have additional 1mm inox on 6 cm brick floor... Any suggestion is welcome. |
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Post by travis on Jan 4, 2018 19:41:20 GMT -8
I like the look of the stove. Good job man.
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Post by bulbius on Jan 5, 2018 11:00:15 GMT -8
When you closed the primary air inlet and the stove filled with woodgas, it looked like the flame in the riser slowed significantly or stopped altogether. Does your stove not have a P-channel or some other form of tertiary air supply? In a firebox that hot you should be able to virtually stop all firebox combustion by closing down the primary air while the heat riser continues to roar away, provided it is being supplied sufficient pre-heated tertiary air. There's a floor P-channel but it's located behind the air inlet so no way to feed tertiary air with the closed air intake. But it would be interesting to do it. |
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Post by bulbius on Jan 5, 2018 11:02:30 GMT -8
bulbius, the air-concrete cracks, but the plaster is holding it. Nice insulation material I plan to use it too. Yeah, I though the same thing. No problems to date. |
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Post by bulbius on Jan 5, 2018 11:18:29 GMT -8
...The space to be heated is large so when it's very cold outside we need to load the stove 3-4 times in a day. The white oven works nicely, after the embers phase it can even reach the full scale at 300° C.
Hi, I would appriciate some more explanation about your white oven. I have similar placement ( donkey32.proboards.com/thread/2307/heater-cast-batchbox-bell-bench?page=4 ) as you but I can reach mux 170C wit a single burn. I did not try two burns one after another... What temperature of the oven can you reach after one single burn from cold or warm heater? My oven is made from INOX and placed over batch box inside the bell. Between the batch box ceiling and oven floor there is 3 cm of cast concrete and 3 cm fire brick (only laid on the batchbox, not glued). Other walls of inox oven face to the bell. I am thinking to place instead 3 cm firebricks some more conductive material like metal. I can not place the oven directly on the batchbox, i need to have 3 cm spacer material in between or air (air is even worse than 3cm bricks). The only difference I see Is that oven is isolated besides its floor and That I have additional 1mm inox on 6 cm brick floor... Any suggestion is welcome. I read the post about your stove some days ago, very nice project. I'm afraid that as you said the concrete and refractory layers over the ceiling of the firebox interrupt the heat transfer to the oven. I would glue to the top of the firebox 3 cm of firebricks and then place the oven. I think the best (if you can) is to remove the metallic base of the oven thus using the refractory itself as the oven floor. |
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Post by pinhead on Jan 5, 2018 11:18:36 GMT -8
When you closed the primary air inlet and the stove filled with woodgas, it looked like the flame in the riser slowed significantly or stopped altogether. Does your stove not have a P-channel or some other form of tertiary air supply? In a firebox that hot you should be able to virtually stop all firebox combustion by closing down the primary air while the heat riser continues to roar away, provided it is being supplied sufficient pre-heated tertiary air. There's a floor P-channel but it's located behind the air inlet so no way to feed tertiary air with the closed air intake. But it would be interesting to do it. I've done it in my Batch Box. It's much easier with the S-Portal but can be done with the P-Channel as well. I haven't tried with the floor channel since neither of my stoves have one. |
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grga
Junior Member
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Post by grga on Jan 5, 2018 13:51:02 GMT -8
I think the best (if you can) is to remove the metallic base of the oven thus using the refractory itself as the oven floor. Thanks for suggestion, I can remove the metalic base, will try it. I will try to glue the 3cm bricks with clay/sand mix. I also think your stove is working very good, based on the video. My burns fine but not as wild as yours with similar wood size. Obviously you have done a very good job! |
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Post by bulbius on Jan 6, 2018 11:49:38 GMT -8
Thank you all for your feedback! This already repays the effort But I have a doubt: as you see in the picture the P-channel opening is higher than the air inlet (you can see it behind the glass), I'm worried that the vertical air flow that cross the section between the door and the threshold will not enter the P-channel just because the direction of the flow it's perpendicular to the opening. Or will it even provoke air suction from the P-channel??  Maybe should I weld a kind of deflector over the top of the P-channel opening to guide the air inside? How can I be sure that the secondary air is working correctly?  |
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Post by Orange on Jan 6, 2018 12:12:13 GMT -8
don't you see it working at around 1:30 of the video? You can put a little flame or tin foil in front to see if the floor channel is sucking air.
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grga
Junior Member
Posts: 76
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Post by grga on Jan 11, 2018 4:49:54 GMT -8
I think the best (if you can) is to remove the metallic base of the oven thus using the refractory itself as the oven floor. Thanks for suggestion, I can remove the metalic base, will try it. I will try to glue the 3cm bricks with clay/sand mix. I also think your stove is working very good, based on the video. My burns fine but not as wild as yours with similar wood size. Obviously you have done a very good job! I have tried it as suggested (glue bricks and remove metal floor) and it is a bit better. At very good load (dry wood and not to big pieces) fire I can now reach 200C but not more. Regarding doubts of secondary air, you could try to add additional deflector if you can notice any difference. you could do it similarly as Peter has it (see: donkey32.proboards.com/thread/2276/project-batchbox-180mm-brickwork-bench?page=3). But probably the air is entering the floor channel as it is relatively cold and wants to stay low.... |
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Maybe should I weld a kind of deflector over the top of the P-channel opening to guide the air inside?