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Post by exoplasmic on Oct 25, 2015 6:36:21 GMT -8
The mold for the "ceiling" above the heat riser. Pic is of the mold + a bag of dry "insulating castable refractory" + a bag of steel needles. I was told a half bag of the needles per bag of castable, for strength. www.dropbox.com/s/59yo3jo2y8cwtqr/2015-10-25%2010.13.32.jpg?dl=0The ceiling will be 3 inches (7.7 cm) thick. The longest span (not including the diagonal) is 28 inches (72 cm) (see tape measure in pic). I was wondering if I should lay the ceiling slab on top of a double row of refractory rope like a gasket. The rope would be bonded to the top of the wall but the ceiling slab would float. I would like to remove the ceiling slab to inspect the condition of the heat riser and the area surrounding it. Once I feel comfortable that the whole system is properly tuned maybe I could make a more permanent seal. I also want to see how much ash settles in this area. It should be turbulent so probably not very much. I also want to see about a short wall between the heat riser and the down-draft channel. This wall may alleviate some of the concern I and others have about a 180 degree turn in the flow of combustion gases. Also note the irregular shape of this part of my system. If I had to do it over I would have made it more square.
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Post by peterberg on Oct 25, 2015 7:47:05 GMT -8
What I do is keeping the top slab on a repractory rope or strip of superwool at all times. It isn't possible to fix it permanently to the walls of the bell because the top slab will expand more and quicker as compared to the walls.
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Post by exoplasmic on Oct 25, 2015 10:26:26 GMT -8
Peter Thanks for the info about the ceiling above the heat riser; let it float on ceramic rope.
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Post by daniel on Oct 25, 2015 14:49:09 GMT -8
Regarding the upper part of the bell, when should the refractory brick be layed is it ok to start in the last third or at half of the bell. Also if the top slab is made of metal I profile with refractory bricks layed between them will they hold?
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Post by daniel on Oct 25, 2015 15:01:20 GMT -8
I am not finised yet with the bell, got to 1/2 from the firebox floor of the total height of 180 but I have burned small fires using only pine and not large pieces. It burns impressive even with the temporary door I had held in place with wire and with lots of gaps around which did not help. The P-channel is replaceable and I made everything including the firebox and the riser replaceable at a later time. I can't imagine how it will burn with a full load of dry quality wood. I already layed about 200 bricks for the lower part of the bell and it is a massive thing already. Does anyone made some experiments with metal tubes for heat extraction on top near the riser ?
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Post by exoplasmic on Oct 26, 2015 18:59:39 GMT -8
Regarding the upper part ...Also if the top slab is made of metal I profile with refractory bricks layed between them will they hold? I don't understand what profile with refractory brick. Also, "between them" ...does that refer to the metal sheet that acts as the ceiling? Regarding your idea of having the top 1/2 or 1/3 of bell be fire brick: I think regular brick would be fine if it's clay brick. But I am guessing it is more important that the mortar should not be Portland cement based. Thanks for mentioning that Daniel. I'm going to use refractory mortar for the upper half of the bells. Having refractory mortar instead of "type-s" mortar (sand+portland cement) is one less piece that can fail over time, especially since I was warned that Portland cement will spall and go to powder after temps exceed 200-300 F. Actually, does anyone know if that's true? >300F (>150 C) is very bad for portland based mortars?
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Post by daniel on Oct 26, 2015 22:56:18 GMT -8
I meant that the ceiling of the bell to be made by metal beams spanned across the bell and between them to simply lay firebrick and the cover them with clay and sand.There will still be the lower part of the beams exposed to heat and fires but the ceiling will be able to slightly move around due to expansion with heat which is very important. Regular cement will fail when exposed to heat over time and I would not take a chance, I have no trace of portland cement and went to great lenghts to avoid heat going to the concrete floor. I don't think is worth taking the risk. Now since I need about 200 firebricks more to finish the bell I am contemplating what else I can do. I was thinking about putting these metal pipes in the ceiling to extract hot air and take it somewhere else for storage or for use. Does anybody know if steel will hold up above the riser or a little sideways? I understood that the upper of the bell or the last third part of it should be made of refractory brick not regular brick to withstand over time the gases not necessarily the heat, does anybody know ?
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Post by satamax on Oct 26, 2015 23:02:11 GMT -8
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Post by dustylfc on Nov 4, 2015 14:17:54 GMT -8
Any updates
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Post by daniel on Nov 4, 2015 14:25:12 GMT -8
Hi Dusty, what updates are you reffering at, about the bells?
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Post by dustylfc on Nov 6, 2015 5:50:36 GMT -8
Hi referring to the builds currently under way EXO and yourself
EXO was doing really well including pics I was following his build closely as I wanted something similar and learning from his build aswell as yours one can learn more off pics I feel
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Post by exoplasmic on Nov 6, 2015 8:22:14 GMT -8
I've been making progress. However, I backtracked a bit when I realized that regular mason mortar (sand + portland cement) would not hold up to high temp for the brick bell chambers. So I tore down what I had built and rebuilt it with refractory mortar. Still, some of the cooler areas have regular mason's mortar, like the lower area around the heat riser. Let me explain what surrounds the actual riser: the riser tube is 8 inches in diameter and 57 inches high, by 2 inches thick of high temp "castable" refractory with 2 inch steel needles for strength. Then 2 inches of refractory blanket all the way around. Then 2 to 6 inches of loose perlite. Then 2.5 inches of refractory brick, then 1/8 inch cardboard. Then 3 inch solid clay pavers set with type S mason mortar. The clean out doors (2) are in place. The single walled bells are about 4 feet high (122 cm). Price of Mason's mortar is $5.50 (80 lbs or 36kg). Price of refractory mortar is $55 (55 pounds or 25 kg)( at Menard's). I'm on my 4th bag of refractory mortar. Need 2 more to finish the job. I don't know if this is ok or not but I supplement the refractory mortar with 1/5 mason cement to 4/5 refractory mortar, just to save a few pennies. Sometimes I throw in some powdered fire clay (1/8, dry volume/volume). I downloaded the material data sheet for the refractory mortar. It's good up to 2550 F. (1400 C). Guess what! It has up to 40% Portland cement! (Actual listing is 20%- 40%). I suspect that the calcium alumina cement is the key refractory ingredient at 0-55% . MSDS for AKONA® Refractory Mortar www.tccmaterials.com/pdf/AKrefractorymsds.pdfAdditional specs on mortar: http:///www.tccmaterials.com/mobile/product.cfm?id=441 With 5 kids (ages 9 -19) and a full time job (in US that's 40 hrs/week) I can't believe I'm so far along. Hopefully another week or so and I'll start some small fires. Also, I need to buy a lightning rod for my very fancy chimney. Wouldn't want that to be destroyed. That's another expense my wife doesn't know about yet. She won't be happy!
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Post by daniel on Nov 6, 2015 10:28:31 GMT -8
Hi, Yes now the build it is officially finished and is working amazing, I did not believe that it can heat a house for 24 hours but now I see that. As far as the pics I have a video underway but I will try to add some pictures here and a link to video, I was trying to achieve a good quality efficient heater while not spending way too much but I did not to cut down on the important parts since I could not have taken the chance to rebuild. Some technical decisions had to be taken to move ahead so I decided not to risk with a second bell since I did not have a space for it, however I could have come up with a way to put it in place but this can be done later. The heater is working amazingly and I think that is a lot of heat that could be further extracted without affecting the draft in a significant way. For the moment until I finish the door the heater is working without one and the air admission is too big. FIREBOX TOP INSIDE THE BELL HEATER
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Post by daniel on Nov 6, 2015 11:16:45 GMT -8
Hi, the riser is enclosed in a stainless steel riffled tubing with an inside sleeve of high temp inside diameter 200mm, between the riser and the tubing there is perlite, expanded clay (this are peanut size and bigger pieces of burned clay glasslike material with a porous structure) all this is mixed with a bit of clay powder, refractory mortar. Around the sleeves there is a piece of thin cardboard to allow for expansion and extraction of the sleeves if needing change. I poured the mix between the sleeves and the tubing. (I made it way to wet and knew that at the time but I figured it will loose the water, it did but it takes a whole lot of time and makes the material weaker, the idea was to make this mix be able to stand by itself if the tubing ever fails).
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Post by exoplasmic on Nov 6, 2015 11:17:21 GMT -8
Daniel Wow is that nice! Well done! I can see a chimney to the left but don't see where it connects. Can you post a photo of how the smoke goes from the bell to the chimney?
The fire brick looks like the kind they use in the Russian videos. I wish there was a source around here in Michigan for that kind so I could price it.
How did you make the ceiling for the bell?
Do you have to light a small fire at the base of the chimney to get the air draw started? Any smoke in the room? I have a daughter with slight asthma so I'm worried about that a bit, especially if I make a 2nd masonry heater for the 1st floor. Mine existing project is in the basement where we don't spend a lot of time. That may change when I fix it up a bit more.
If I make a second one it will be a six inch system and much nicer. I may even purchase it and install it myself. I've seen some nice kits online.
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