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Post by rakettimuurari on Aug 28, 2017 8:06:19 GMT -8
Hello forum! My name is (mr) Antti Säippä; I am from Lempäälä, Finland. I have been following the forum one year now and found it as I was building standard RMH in my sauna's dressing room (https://permies.com/t/60768/RMH-sauna-cabin-success#516820) utilizing permies.com. I have a problem... I feel I am getting knee deep or more into rockets  ... and after this maybe neck deep.
But still - I want to express my thanks for all this freely and enthusiastically shared information and especially the pioneering work and heavy duty rinse-and-repeat-field testing made by Peter and the others! You really have smoothed out the entry level for all this.... Batch rocket / brick sidewinder with cast riser / fire burning through a baking oven in to the single brick bellHave been planning a batch rocket for my living room a year now. My challenge is to fit 160mm system to a relatively small space and with baking oven. At the moment I am sketching it up. It will replace a small, maybe 400kg old open fireplace which has closed fireplace module installed. PLAN in SHORT:Dimensions of the heater:
width: 135cm
depth: 60cm
height: 185cm
Firebox will be placed on the right third when faced from front. Sidewinder design will open to the left from firebox (-still if faced from front-)
placing the riser in the middle of the width of the heater.
Riser top will be connected directly to the bottom of a compact and vaulted baking oven (w: 41cm, h: 23cm, d:53cm), essentially the oven thus
having a 160mm opening inside in the floor, just adjacent to the back wall of the oven. From there the burning gases would travel along the oven vaulted ceiling
towards the baking oven door some 30cm, finally entering through the smoke channel in the vaulted ceiling some 10cm before the baking oven door. After the oven the gases are
able to freely rise to the top of the bell... Rest is just normal batch rocket & bell operation. Behind the whole installation (basically separated by fire insulating wool,
stands old firewall with 6m high brick chimney with excellent draft.
I will install also a direct flow summer damper on topside of the bell for summer baking and for lighting the thing . Theoretically the baking oven could also be operated directly by
burning the wood in it but i don't really see point in it as burning will be more unclean...
I got the idea of the oven construction one night but then bit later- like always - realized that i was not the first one... kind of:
mainewoodheat.com/masonry-heaters/the-albiecore/
I would appreciate any thoughts about the planned construction. Is there any deadly flaw related to operating principles? I would also like to pose one more exact question too. How much can the depth of the port be varied from given dimensions?
Originally i was settling with 57mm which is the standard width of the Finnish fire brick on its side... However after a successful mold experiment with castable refractory I am going for a 35mm thick cast riser core surrounded by perlite filled brick box (latter also partly supporting the oven). However, because of the vertical mold the riser will be round and uniform all the way with its 3,5cm thickness. This again poses a problem because i'd like to have the firebox walls made by bricks laying on their side (that 57mm) for strength and solidity. This would result in port depth of 35mm (riser wall) + 57mm (firebox side wall) =92mm. Peter wrote somewhere earlier that thing get worse especially after exceeding 100mm if I got it right... Any thoughts? Or should i narrow the port to compensate the added depth to maintain smooth operation and stream properties? I don't think I have proper means to swipe and shape the ready cast riser core to fit it closer to firebox thus shortening the depth of the port, and yet getting it to be even and smooth enough to seamlessly attach to port opening on firebox wall. could any of u to figure a solution for this? Thanks for your sharing and help! -Antti- **It has begun - i ordered the firebox door**
www.talotarvike.com/svt-takkaluukku-410-kaasutiivis-325x290mm-oikeakatinen-p40913
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Post by satamax on Aug 28, 2017 17:42:11 GMT -8
Terve Antti.
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Post by rakettimuurari on Aug 30, 2017 0:09:49 GMT -8
Hi Satamax! You seem to have an over-watch everywhere |
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Post by peterberg on Aug 30, 2017 9:14:01 GMT -8
Hi Antti, welcome to the boards. You want to build a 160 mm system inside a bell of 135x60x185 cm. The bell looks quite cramped, what's the projected thickness of the walls? Essentially, by inserting an oven like that you are building an untested construction. Maybe you need to look at the designs of Yasin Gach of France. His sidewinder 6700 W do sport a working black oven and is a very lean build. uzume-asso.org/batchrocket_plans.htmlYour remark about "just normal batch rocket & bell operation" made me smile, keep in mind development started back in 2012, much more recent than the contraflow concept which is well-known in Finland. Personally, I don't like bypasses that much, in particular when situated in the top of the bell. When you want one, please place it one third of the bell height down to avoid the highest temperatures. How much can the depth of the port be varied from given dimensions? Originally i was settling with 57mm which is the standard width of the Finnish fire brick on its side... However after a successful mold experiment with castable refractory I am going for a 35mm thick cast riser core surrounded by perlite filled brick box (latter also partly supporting the oven). However, because of the vertical mold the riser will be round and uniform all the way with its 3,5cm thickness. This again poses a problem because i'd like to have the firebox walls made by bricks laying on their side (that 57mm) for strength and solidity. This would result in port depth of 35mm (riser wall) + 57mm (firebox side wall) =92mm. Peter wrote somewhere earlier that thing get worse especially after exceeding 100mm if I got it right... Any thoughts? Or should i narrow the port to compensate the added depth to maintain smooth operation and stream properties? I don't think I have proper means to swipe and shape the ready cast riser core to fit it closer to firebox thus shortening the depth of the port, and yet getting it to be even and smooth enough to seamlessly attach to port opening on firebox wall. could any of u to figure a solution for this? As of today, I am opposed to make the port deeper and narrower, this is a leap away from the tested and proved design. You are on your own when trying to build a changed design. What I would recommend in your case: whatever you do, you have to cut some bricks. Cut the bricks left and right of the port under 45 degrees at the back, so they'll fit nicely to the riser and use a proper high-temp refractory cement to fix it together. This way, the port could be less deep like, say, 60 mm. An often used alternatively method is to cut up the riser left and right of the port so there's a flat surface to place against the firebox bricks. |
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Post by rakettimuurari on Aug 31, 2017 0:47:40 GMT -8
Thank you Peter for welcoming and also for your observations! I enclose some drawings for better illustration (those with the work label "batch devil" --> long story..) drive.google.com/drive/folders/0B_O6G3ixIMfHdm1sN3R1VEdpbTA?usp=sharing(seems to work only by "open in new tab" - option) "The bell looks quite cramped, what's the projected thickness of the walls?"This is making also me feel bit uneasy; not to mention that old chimney itself is part of the whole area. In my estimates I have no chance to get even close to 5 m2 ISA but I was hoping that quite massive oven structure with its surfaces plus the supporting column would amend some of the missing wall surface. I was planning to lay bricks flat (124mm wall thickness) in front and sides with back wall being bricks on sides (57mm). My wish would be to delay the heat transfer more and have more solid structure. Somehow I felt uneasy about thinking that the walls would be only 57mm thick and height of a man. I was planning to make sure that gasses and air have movement routes on top, both sides and also below the firebox. But cramped it will be; it looks more like a contraflow designed in intoxicated state than a bell truth to be said. How about removing the back wall of the heater and anchoring the sides directly to the original brick firewall behind the heater? The wall is in the middle of the house (built in 30's) and has stone slabs as decorative surface. It had originally relatively big contraflow baking oven standing against it. Oven was then replaced with small open fireplace at 70's 4 owners ago and the closed Harvia fireplace insert was added some 30 years later which was two owners ago. Behind the wall in kitchen there is an opening for another chimney. I am quite sure there have originally been a wood-stove inserted. drive.google.com/open?id=0B_O6G3ixIMfHOFo5Wi1fZ0JaMW8(seems to work only by "open in new tab" - option) "Essentially, by inserting an oven like that you are building an untested construction. Maybe you need to look at the designs of Yasin Gach of France. His sidewinder 6700 W do
sport a working black oven and is a very lean build.uzume-asso.org/batchrocket_plans.html"
Yes; that is true but I kind of like to research this kind possibility with oven. I will probably prepare a replaceable module with which I can practically just extend the riser through the oven ceiling if a need arises. I wont hard seal the roof of the whole heater before i know  The oven would practically has 160mm hole in the bottom back left corner and then an oven wide slit with system CSA? or more? on the roof of the oven closer to the front and the door. I checked Yasin's plan. I looks interesting and lean yes - I will still need to put it in pieces and give closer inspection; I am just somehow reluctant towards slim walls... "Your remark about "just normal batch rocket & bell operation" made me smile, keep in mind development started back in 2012, much more recent than the contraflow concept which is well-known in Finland." Now you made me smile You are very right in that. It is just my biased trajectory as I have read so much more about RMH's and BR's than our old contraflows. It is getting balanced; I got handful of old contraflow plans and guidebooks just recently and been reading them for a month now. "You have to go far to see what was close to you".. or how to they say? In short, with my planned construction I am hoping to avoid building more complicated secondary burn chamber (replaced by the batch rocket) and carefully measured and lined smoke channels (replaced by the bell operation). "Personally, I don't like bypasses that much, in particular when situated in the top of the bell. When you want one, please place it one third of the bell height down to avoid
the highest temperatures."
"As of today, I am opposed to make the port deeper and narrower, this is a leap away from the tested and proved design. You are on your own when trying to build a change
design.What I would recommend in your case: whatever you do, you have to cut some bricks. Cut the bricks left and right of the port under 45 degrees at the back, so they'll
fit nicely to the riser and use a proper high-temp refractory cement to fix it together. This way, the port could be less deep like, say, 60 mm. An often used alternatively
method is to cut up the riser left and right of the port so there's a flat surface to place against the firebox bricks."I gladly take heed of your advice about the bypass. Same goes with the port depth - thanks! It also dawned to me suddenly that it would be no problem to cut the bricks as I will be deeply immersed in brick cutting business anyways. My sincere thanks for your observations, -Antti- |
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Post by peterberg on Sept 1, 2017 2:16:18 GMT -8
About slim walls: as you are able to see in Yasin's designs the firebrick walls are on edge. But that isn't the whole story, most heaters like that are built with an outside skin of brick or unfired mud bricks, even concrete street paving could be used. So the whole of the structure is much more solid and stable than you would expect at first sight. Those double skinned bells are slower in emitting heat than their single skin relatives. So there's more mass in there and the outer skin won't crack as easily due to heat expansion, as long as the outer skin is kept separate from the inner skin. I am led to believe Rockwool sheets of 10 mm thick are available in Finland, those are ideal for separation purposes and the insulation value is very minor when the temperatures are taken into consideration.
Your intention seems to keep the heater small, why are you planning to build a 160 mm model then? Maybe because that's the chimney size?
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Post by rakettimuurari on Sept 1, 2017 10:38:40 GMT -8
Evening Peter and thank you for your answer! About slim walls: as you are able to see in Yasin's designs the firebrick walls are on edge. But that isn't the whole story, most heaters like that are built with an outside skin of brick or unfired mud bricks, even concrete street paving could be used. So the whole of the structure is much more solid and stable than you would expect at first sight. Those double skinned bells are slower in emitting heat than their single skin relatives. So there's more mass in there and the outer skin won't crack as easily due to heat expansion, as long as the outer skin is kept separate from the inner skin. I am led to believe Rockwool sheets of 10 mm thick are available in Finland, those are ideal for separation purposes and the insulation value is very minor when the temperatures are taken into consideration.
You are right about the skin thing. Most of the contraflows here today get the second layer; it is also very easy to surface-finish as cover does not expand so much. Most of the masons use 10mm wool in between as it gives automatically good separation joint and more freedom in bricklaying. I will be using same stuff for expansion joints too. Back in the days they used normal cardboard and best ones went by the eye estimate. Double layer was my original plan too... until i started to count the mass. With covering layer - even from the lightest bricks - the mass passed 2000kg (the walls and firebox by single skin will still have some 1600kg +; oven not counted in that!). I want to have both - delayed heat transfer as well as powered one; so i thought i will go first with single skin but if room temperature is too high after a batch burned, I have been considering about adding the cover masonry afterwards. I am after clearly warm surface but also at least 12h storage, but I dont have math to count it so I thought to experiment. Single layer system (12,4cm) should have the highest surface warmth some 5,5 hrs after lighting the fire and cool down is probably affected by the mass? Some Finnish mason wrote that it would be better to have cover masonry thinner than the body masonry itself? What are your thoughts on that? All in all I feel its better to make it too hot/light first than too cold and heavy. Your intention seems to keep the heater small, why are you planning to build a 160 mm model then? Maybe because that's the chimney size?
Yes; Chimney size has been the main reason and also habits. Somehow the firebox in 160mm BR still feels so small compared my current one so it was hard to think to have even smaller one... I was after max potential. You have made to rethink this however. I should not be too worried about the footprint though as I am quite sure the original heater has been really much larger.
What would you think about this:
I could try to expand the area of the heater depth wise by adding maybe 10cm more depth to whole footprint. This way i could free the back wall ISA completely, the firebox and oven being entirely separate from it (not attached to it as in original plan). Do you think that only some 3 to 5 cm gap behind the firebox and oven would enable the free flow for gases? With this maneuver I quickly counted total ISA estimate would be around 5.6m2. Down-scaling system to 6" could be already risky? My ISA estimate table
Do you think it could work with this change as 160mm CSA system?
Cheers,
-Antti-
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Post by peterberg on Sept 3, 2017 8:27:38 GMT -8
I want to have both - delayed heat transfer as well as powered one; so i thought i will go first with single skin but if room temperature is too high after a batch burned, I have been considering about adding the cover masonry afterwards. I am after clearly warm surface but also at least 12h storage, but I dont have math to count it so I thought to experiment. Single layer system (12,4cm) should have the highest surface warmth some 5,5 hrs after lighting the fire and cool down is probably affected by the mass? A very simple rule of thumb: every 100 kg of active mass provides for one hour of heat release. Some Finnish mason wrote that it would be better to have cover masonry thinner than the body masonry itself? What are your thoughts on that? All in all I feel its better to make it too hot/light first than too cold and heavy. The inner skin gets hotter than the outer skin, so more mass in the inner skin means a larger "hot storage". My heater is double skin, 12 cm inside and 5 cm outside. And yes, it's slightly slower and lower temperature than the single skin of 12 cm. The downside of double skin and lots of mass, if you prefer to see it that way, is the heat is emitted very regularly at the same power over most of the 24 hour cycle. As opposed to single skin which tend to emit in bursts that goes down to a trickle before the next burn. Somehow the firebox in 160mm BR still feels so small compared my current one so it was hard to think to have even smaller one... I was after max potential. You have made to rethink this however. I should not be too worried about the footprint though as I am quite sure the original heater has been really much larger. There's a thing about a batchrocket as compared to most heaters: all the fuel in a batchrocket should be loaded front-to-back, no campfire or log cabin style. So a load is fairly massive, with only small openings between the logs. A 150 mm system could accomodate about 6 kg in one batch of birch or beech. I could try to expand the area of the heater depth wise by adding maybe 10cm more depth to whole footprint. This way i could free the back wall ISA completely, the firebox and oven being entirely separate from it (not attached to it as in original plan). Do you think that only some 3 to 5 cm gap behind the firebox and oven would enable the free flow for gases? With this maneuver I quickly counted total ISA estimate would be around 5.6m2. Down-scaling system to 6" could be already risky? My ISA estimate table
Do you think it could work with this change as 160mm CSA system?I would regard that space behind the firebox rather cramped, 10 cm would be sufficient I would say. And yes, 5.6 m² would be adequate. |
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Post by rakettimuurari on Sept 5, 2017 4:10:24 GMT -8
I want to have both - delayed heat transfer as well as powered one; so i thought i will go first with single skin but if room temperature is too high after a batch burned, I have been considering about adding the cover masonry afterwards. I am after clearly warm surface but also at least 12h storage, but I dont have math to count it so I thought to experiment. Single layer system (12,4cm) should have the highest surface warmth some 5,5 hrs after lighting the fire and cool down is probably affected by the mass? A very simple rule of thumb: every 100 kg of active mass provides for one hour of heat release. Some Finnish mason wrote that it would be better to have cover masonry thinner than the body masonry itself? What are your thoughts on that? All in all I feel its better to make it too hot/light first than too cold and heavy. The inner skin gets hotter than the outer skin, so more mass in the inner skin means a larger "hot storage". My heater is double skin, 12 cm inside and 5 cm outside. And yes, it's slightly slower and lower temperature than the single skin of 12 cm. The downside of double skin and lots of mass, if you prefer to see it that way, is the heat is emitted very regularly at the same power over most of the 24 hour cycle. As opposed to single skin which tend to emit in bursts that goes down to a trickle before the next burn. Somehow the firebox in 160mm BR still feels so small compared my current one so it was hard to think to have even smaller one... I was after max potential. You have made to rethink this however. I should not be too worried about the footprint though as I am quite sure the original heater has been really much larger. There's a thing about a batchrocket as compared to most heaters: all the fuel in a batchrocket should be loaded front-to-back, no campfire or log cabin style. So a load is fairly massive, with only small openings between the logs. A 150 mm system could accomodate about 6 kg in one batch of birch or beech. I could try to expand the area of the heater depth wise by adding maybe 10cm more depth to whole footprint. This way i could free the back wall ISA completely, the firebox and oven being entirely separate from it (not attached to it as in original plan). Do you think that only some 3 to 5 cm gap behind the firebox and oven would enable the free flow for gases? With this maneuver I quickly counted total ISA estimate would be around 5.6m2. Down-scaling system to 6" could be already risky? My ISA estimate table
Do you think it could work with this change as 160mm CSA system?I would regard that space behind the firebox rather cramped, 10 cm would be sufficient I would say. And yes, 5.6 m² would be adequate. **************************************************************************************************************** Thanks again for very useful information Peter. I will work it out to have that 10 cm behind the firebox and oven for free ISA and gas movement. I also just found that most of the old contraflow structure cards I got, seem to have always the vertical smoke channels minimum of 70-80 mm wide, although of course the bell structure and operation is bit different. I just demolished the old fireplace yesterday. It ended up to be a tough small cubicle as the creators had been using very much of iron strengthened concrete Later this week I'll open the surrounding floor to inspect the foundations. On the ground there will be a car sized area laid full with large granite boulders with masonry surface on top of them (checked under the house), but between that and the floor I don't know yet. If needed, I am planning to cast an iron strengthened slab of 10 cm on top of the old slab which is only of the previous installation size (90cmx60cm), anchoring this top slab directly to granite with concrete pillars and installing bitum cloth pieces in between for capillary humidity insulation. In that case I will be also able to expand the footprint of my BR to be less cramped and also ensure that foundation is secure enough. I will also then have an extra margin for potential skin masonry later on. Ordering materials tonight regards, -Antti- |
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Post by Orange on Oct 1, 2017 5:55:16 GMT -8
what about putting baking oven on a riser, when needed? top of the riser is hot so all what would be needed is a large bowl on top, probably with reflective surface inside and some insulation outside.  |
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Post by rakettimuurari on Oct 21, 2017 5:40:10 GMT -8
![]() Hi again forum, At least my new batch rocket stands now! And thanks for your input orange! However I followed the original plan and now all is ready and I am waiting in order to let the heater dry. After two weeks will start with break in fires. I managed to keep minimum 10 cm opening on firebox and oven sides and back. Ovens support columns brought extra ISA so I went on with by pass installation (cast iron). According the old tradition I burned the plans/ drawings after roof was on place and draft was excellent. We'll see about the real operation... I enclose links to picture and sketch up plan. I left the slit on oven vault very large in order to ensure the stratification of gases. I hardly can wait to test the operation. Estimated final mass is around 2,5 tons. I will give detailed info as I start the runs in 2 weeks. Sketch up: drive.google.com/open?id=0B_O6G3ixIMfHbDFsQUdSdXpaenMPicture: drive.google.com/open?id=0B_O6G3ixIMfHT1c5RGFIdGNLaHMEnjoy the autumn; we got minus 4 Celsius yesterday early morning -Antti- |
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Post by Orange on Oct 25, 2017 4:06:34 GMT -8
looks good, would be interesting to see temperatures.
from the sketcup it looks like 150mm system as one side of riser is flat. And I guess you close the bottom air intake when burning?
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Post by travis on Oct 25, 2017 9:20:32 GMT -8
Wow this is a great project! I really like the oven added in like in many masonry heaters. Does the sidewinder make anything more complicated or is it just the same as a riser directly behind the firebox?
Great job so far! Ill be watching to hear your results.
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Post by Jura on Oct 25, 2017 11:07:31 GMT -8
Could you tell me what material you used for the visible below gray and orange ceiling? and the gray vaults, please  |
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Post by rakettimuurari on Oct 26, 2017 2:31:01 GMT -8
Hi again, Orange: It is 160mm; i was just lazy shaping in sketchup with irregular shapes. Riser is round. I installed both intakes for air (door and under) as I definitely wanted an ash box so the underair is experimental. If needed i will install a closing ash hatch and enlarge the air channels in the door. So far when burning a handful of kindling every morning and evening it burns like a furnace with underair open. Next week I'll start with regular cord-wood and gain more info. travis: My understanding is that it will work very similarly as long as measurements hold. "...The differences in firing behavior are fairly small so this will be a good alternative..." Info from here... I wanted the oven as I bake my own sourdough bread couple of times a week and u just cant beat the masonry oven in that... Most I am looking forward to see the baking behavior of the oven and the temps; about the rest of the heater I am quite assured already. White flame is just nice looking thing. So far i had no need to even use the bypass. My only concern about the heater operation in general is that will there be enough space for the proper stratification of the gases to occur. I used every cm I had whatsoever. Jura: All grey material in plan is castable refractory mass, also the vault (made from 3 pieces for flex joints). Orange is fireplace refractory wool plate (10mm around the oven and firebox; 50mm on roof). Roof refractory plates are supported by shaped regular bricks to omit roof corners gathering too concentrated heat and shortening the hang of the plates thus giving strength. **Curious thing about my chimney stack (from 1936) is that it is an half brick sized (ancient large sized brick) from heater on but widens up to be something like 1,5 brick sized in upstairs when another half brick channel from kitchen (exit air) joins it. That makes chimney constantly warmer than outside thus creating constant draft which again serves the heater very well. Just to open the heater damper 10min before firing and close the kitchen exit air does the trick. Today's regulations in Finland would not allow similar design |
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... and after this maybe neck deep.
The oven would practically has 160mm hole in the bottom back left corner and then an oven wide slit with system CSA? or more? on the roof of the oven closer to the front and the door. I checked Yasin's plan. I looks interesting and lean yes - I will still need to put it in pieces and give closer inspection; I am just somehow reluctant towards slim walls...
