grga
Junior Member
Posts: 76
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Post by grga on Nov 17, 2017 3:17:45 GMT -8
Here's some progress made, after quite some time… I think there are no more time-consuming decisions to make and to solve them such as they were: - Outside fresh air yes/no, how? Since I had 150mm plastic pipe already in the floor supplying outside air I decided to use it. I simply connect if to the ball wall and it can be opened or closed if needed. Fresh air is then going to the room and is sucked from the heater when burning. - Bypass install it or not, my existing chimney pipe was at 1.8m height… I have lowered it a bit and made inox sliding bypass door. Now the bypass is a bit higher than half the bell height. I do hope there won’t bee too much friction when the sliding door get hot? - Use white oven or not and where to place it. In spite recent disappointment with white oven operation (Dvavolk and Yura) I will give it a try. Why? Because it will let me easier access (it could be pulled out) to the bypass if some maintenance will be needed. Also I believe the heater is nicer with the oven and it would hopefully be hot enough (at least 200C). I made it from 1mm sheet metal inox and its floor is removable so I can add 3 cm schamote brick between the core and oven or have just air between or even remove the floor and place some mesh to have black oven… And the photo of the build I will make internal ISA close to 8m2 which is a bit more than recommended 7.6m2. This should be fine as I have a bypass and because the bell wall close to the house wall is isolated with 2 cm stone wool and would therefore get hotter faster than the other three bell walls – does this make sense? And for the bell top I plan to use 7 cm thick CAC concrete plate, covered with 5 cm stone wool and over it 8 cm of regular Portland cement concrete. Any thoughts about that, what will be the expected max temperature on the top outside surface of the heater?
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Post by Orange on Nov 17, 2017 8:58:17 GMT -8
-why have outside air when you can just slightly open the windows? Heaters dont like cold air.
-I guess bypass is recommended for non-standard builds
-oven on top of the bell or over riser to get high temps
-you can lower the ISA by puting insulation on inside the bell
-riser can spit 1000C so cement will probably crack, regular stone wool damages over 250C, why not put scrap metal plate and air-concrete (ytong) for insulation?
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grga
Junior Member
Posts: 76
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Post by grga on Nov 17, 2017 14:45:29 GMT -8
Orange, thanks for suggestions. In am beginer learning from my mistakes and experiences od you guys in this forum.
I think 1000C is only in the botom of the riser. Youtong is not good for high temps, much worse than stone wool which can easily handle 600C and more. I am thinking of using calcium aluminate cement concrete, which by my experiences can easily handle hots. I have positive experiences with my smaller batch box made from it and wood pizza oven. On top of the bell temps are much lower than in the core.
fresh air is exactly the reason you said that you do not need to open windows which closed are quite air tight. cold air in the room or in the stove. Stove has some 700C and do not notice difference between 20 or - 5. on the other hand people can notice cold air moving at their feet towards the stove...
For oven you are right, but my riser ends at 1.8m and this is to heigh for oven there, not practical. The core ceiling is very hot though. But probably oven will not function optimally as figured out by others...
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grga
Junior Member
Posts: 76
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Post by grga on Nov 24, 2017 13:56:29 GMT -8
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Post by peterberg on Nov 25, 2017 0:43:55 GMT -8
Should the last row of inner bricks of the bell be angle cut or this is not so important? In a bell system it is largely irrelevant since the velocity of gases is so low. A bell could have any shape as long as it's wide enough to slow gases down. That's why hollow and even dead-end benches works so well.
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Post by Orange on Nov 26, 2017 10:12:23 GMT -8
Should the last row of inner bricks of the bell be angle cut or this is not so important? I mean as in I think this cut on the riser is just to direct ashes to fall into the riser or bell.
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grga
Junior Member
Posts: 76
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Post by grga on Dec 4, 2017 1:52:31 GMT -8
It will be heating this year... Yesterday I made first small fire and the draw was perfect, no smoking even with no door. Fire was close to the port. Will gradually increase fire and dry the heter before making full fire in 14 days the performance of the heter and the oven will be known. An some more pictures of the heater: Cleaning door Inside view, the ceiling is cca 40 cm above the riser. Topping made from CAC concrete, 2 parts cca 50x50cm Ceiling is isolated by 3cm stone wool and then covered by regular Portland concrete (4cm) Sliding bypass. I think it will not be needed, at list at first fires there was no smoke back. Anyway it is there if needed. The inside view through the cleaning door. The chimney intake (closed) is seen at the right/back
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Post by esbjornaneer on Dec 5, 2017 0:53:42 GMT -8
Hello grga, nice pics of a lovely build. Please tell me what is the thing I think is a horizontal silver/aluminium tube is in the heat riser picture? Is it the fire box wrapped in insulation?
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Post by Dan (Upstate NY, USA) on Dec 5, 2017 2:26:28 GMT -8
I think the "tube" is just the top of the cook oven.
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Post by Jura on Dec 5, 2017 2:31:49 GMT -8
Please tell me what is the thing I think is a horizontal silver/aluminium tube is in the heat riser picture? IMHO i s the ceiling of the white oven.
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Post by esbjornaneer on Dec 5, 2017 7:49:48 GMT -8
Yes of coarse it is! I just could not make sense of it from that specific picture, when looking at the first pic of the page it makes sense!
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grga
Junior Member
Posts: 76
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Post by grga on Dec 5, 2017 12:21:56 GMT -8
yes this is the white oven made from 1mm inox sheet.
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grga
Junior Member
Posts: 76
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Post by grga on Dec 8, 2017 0:50:22 GMT -8
After 5 days of slowly increasing burning I now load 1/5 to 1/4 of the full batch. If burns fine, draw is good even although heater is probably stil wet. At building each brick was put to the water for a minute or more...
The heter gets slightly warm, I can hardly fell it by hand. So I am thinking will it warm much more with a full load - what do you think the max outside temperature of a double wall heater would be (my internal ISA is cca 7.9m2)?
Interesting is also that the top of the heater is colder than the middle part - this could probably be because the upper bricks were build later and are therefore less dry?
How long should I carefully dry the heater, when I should start with 1/2 a load when with the full load?
The white oven max temperature up to now was 60C. Hope to be much more at full burn.
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grga
Junior Member
Posts: 76
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Post by grga on Dec 8, 2017 2:25:21 GMT -8
Peter some time ago you advice to modify floor channel so to bent the 45 degree part closest to the port vertically - to prevent it begin to close to the port. I was thinking if I could simply cut it as shown in the image. That way its corners will not be too close to the port and it will still cover the floor channel and direct air in the port...
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Post by peterberg on Dec 8, 2017 2:42:23 GMT -8
Increase the load every day 10%. So it's 20% now, 30% tomorrow, 40% the day after, and so forth. When the load is full after 8 days, start running the heater twice a day with a little more than half loads at first. Every day increase the loads with 10% again, so you're up to two full loads a day in about two weeks. At that point the maximum wall temperature should rise up to 50 to 55ºC. Might be a bit more, because the inner and outer skin are both on edge as I understand it.
Keep in mind there should be some space left above the fuel, 50 mm at least.
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