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Needing Feedback on design for a sidewind 8'' batchbox with 2 bells  RSS feed

 
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Hello community,
I have already posted this here: http://donkey32.proboards.com/thread/3384/feedback-design-sidewind-batchbox-bells
but didn't get much feedback.
This is why I am posting it here also and hope to get more feedback.

I am new to the batchbox and would like to build an 200mm system with two bells, one inside the house and one outside. Connection of both will be done through a 300mm hole in the wall. A 200mm Pipe surrounded with 50mm ceramic fibre blanket insulation will go through that hole. The wall is a strawbale lime plastered wall. This is why I am using 50mm thick fibre blanket insulation.
The back of both bells will be against the wall with a 50mm ceramic fibre blanket in between.

I have built the box out of 50mm ceramic fibre boards. The box will be lined inside (bottom, left and right) with 25mm fire bricks and the internal dimensions of the box will match that of an 200mm system as specified by Peter.
The heat riser will be octagonal and also built out of 50mm ceramic fibre boards. This will seat on 75mm of ceramic fibre board so as to be in line with the inside of the fire box.
The bells will be built out of clay bricks, 230mmx115mmx75mm (from a dismantled chimney), not firebricks as they will not be in direct contact with the fire.

Questions I have:
- What can I use to cap the top of the inside barrel? I was thinking about using 6mm steel plate to have immediate heat release.
- The bottom of the box will be 150mm from the floor seating on a steel frame. The top of the heat riser will be at 1665mm (150+50+25+1440). With the bell being 2200mm high, that will give me a 535mm clearance to the top of the steel plate. That way I hope to avoid having the steel plate exposed to too higher temperatures. Does that make sense or should I raise the bottom of the box by 235mm to have 300mm between the top of the heat riser and the steel plate cap?
- What temperatures can I expect at the transition between the two bells and will the 50mm fibre blanket around the pipe connecting both bells and between the back wall of the bell and the house wall be enough not to affect the straw bale wall? The straw bale wall and the wall penetration have a 30mm lime plaster on top of it.
- The floor is a concrete floor with ceramic tiles. Do I need to add an insulation layer on the floor or will the temperature be low enough as to not affect the tiles and the concrete below?
- I will be adding a clean out opening at the bottom right back of the inside bell and bottom right of the structure supporting the chimney. Is that enough?

Internal Dimensions
Inside bell: width=970mm, height=2200mm, depth=590mm. ISA = 7.4sqm
Outside bell: width=670mm, height=600mm, depth=370mm. ISA = 1.5sqm

I have attached some pictures of the design with some measurements and I am looking for your feedback. All the dimensions on the images are external dimensions
Pictures available here: https://drive.google.com/open?id=1TTte8ubv0mXUnUykzTdTiDUk3rx4VqcT

I have already got suggestion regarding adding a bypass hole up in the first bell directly into the chimney to avoid problems with cold starts.

But instead of a second hole in the wall I would rather just use the clean out opening near the chimney bottom to get the draw started by burning a piece of paper there? I have been advised that this could not work very well.
The big bell is in the living room. The small bell is in an enclosed outside area. We could call it greenhouse as well
I was looking to get enough heat so that we can seat outside comfortably in the winter. It does not get really cold here (Kerikeri, NZ) in the winter at night, lowest is around 6deg celcius outside at night. During the day around 14 deg celcius. But I guess because of the greenhouse effect and the massive outside lime plastered wall that is heated the day, we should get around 12deg celcius inside the greenhouse at night without heating.
I am happy if we can get this up to 18 deg celcius with the second bell.
The room is about 30sqm in total.

Here is videos of my first burn:

Heat riser:


Firebox:


I haven't run it with full load yet.
I intend to run some more tests to make sure that the firebox and heat riser are all air tight.
What should I look for to ensure that the whole system is properly working? I do not have all the tests instruments that Peter has.

Will it be enough to measure how hot it gets at the top of the heat riser?

I know those are lots of questions, so please feel free to answer even it is only one question.

I m looking forward for your feedback.
 
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Hi Nono; Welcome to permies!
Very nice looking build you have there!
I have built several J tubes but have not built a batch box as of yet.  I will try to answer a few of your questions. All are just my opinion.
#1)  I would increase your top gap to at least 300 mm, possibly more as it gets very hot under that riser.
#2) a 2"(50 mm) thick ceramic fiber blanket should provide plenty of protection for your bale wall....
#3)I would think your floor would, with ceramic tile and concrete would be fine. Although under your core could get over heated, was your batch box bottom ceramic fiber board ?
That is all I can try to answer for you Nono,  perhaps an experienced batch box builder may have better answers for you.
 
Nono Junang
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Thanks thomas rubino!

#1) The top gap is planed to be 535mm from the heat riser. So that would align with what you've suggested. In addition I think I will fix around 25mm of ceramic fibre blanket on the steel plate cap in the area just above the heat riser, maybe 400mmx400mm to minimize heat impact on the steel plate.
#3) Yes the batchbox bottom is also 50mm ceramic fibre board as on the picture below. In addition the firebox will be 160mm away from the floor on a steel stand


I will update with pictures and videos as I make progress.

 
Nono Junang
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I have uploaded additional pictures of my progress here: https://drive.google.com/drive/folders/1TTte8ubv0mXUnUykzTdTiDUk3rx4VqcT?usp=drive_open
I have simplified the whole design. No more opening at the back of the wall to a second bell. Instead I have kept the big bell and at the bottom left (view from front) I have an opening going into a second box of bricks and up to the chimney, currently missing.
The second box of bricks is not a bell but rather a channel flowing like a snake (not straight) with opening going right / left / right.
I have made this to increase the path of the exhaust so that it gives even more energy to the bricks. The height of that channel is 1.7m

I plan to cap the top of the first bell with a plate of stainless steel 1.5mm thick. I would also like to make a 200mmx200mm opening on that plate just on top of the heat riser and place a glass there. In addition I would like to have a mirror on the ceiling right on top of that glass so that I can have a view of what is happening inside the heat riser from the top.

Please let me know what are your thoughts
 
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Has the Far North District Council required any particular documentation from you for this build?
 
Nono Junang
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Graham Chiu wrote:Has the Far North District Council required any particular documentation from you for this build?



Went there to talk about the system, but could not find someone who understands what I am planing to build. Best bet would have been to find an engineer that would stamp it, but then that would just drive the costs.
So I decided to build it and document each step, test and refine it to ensure that it meets the National Environmental Standards for Air Quality and then take care of the paper work later with all my test results and documentation.
The bricks are all mortared with lime mortar, so easy to dismantle and tweak.

Done few tests outside and could measure up to 943deg (until I got burned) at the bottom of the heat riser. And I was about 1.7m away from the bottom. So I guess much hotter down there.
Check here: 


Thanks for any feedback regarding the build.
 
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Nono. To film the insides of the heat riser without burning myself, i use a mirror, angled at 45° Sometimes i have to raise it quite a bit to avoid the  steaming. But it's far safer than using the camera directly.

Like this for example.

 
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Nono Junang wrote:The second box of bricks is not a bell but rather a channel flowing like a snake (not straight) with opening going right / left / right.
I have made this to increase the path of the exhaust so that it gives even more energy to the bricks. The height of that channel is 1.7m.


What you did is making the gas path longer, this is what the Austrians do. Just to let you know batch boxes are particular picky about friction in the smoke path, that's why I always advocate bell constructions cause they are virtually frictionless.

Nono Junang wrote:I plan to cap the top of the first bell with a plate of stainless steel 1.5mm thick. I would also like to make a 200mmx200mm opening on that plate just on top of the heat riser and place a glass there. In addition I would like to have a mirror on the ceiling right on top of that glass so that I can have a view of what is happening inside the heat riser from the top.


A steel plate of 1.5 mm thick will warp badly at that location. Think of 15 mm thick and possibly a cross welded underneath to make it more rigid.
That glass will stain with soot during the start of the burn, and will turn to white when the temperature goes up. But in my experience this isn't worth the effort, you won't see anything after a few burns.
 
Nono Junang
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Thanks Peter for your feedback. I originally planed to have 2 bells in another configuration. But because I found it too complex to open the wall I changed that. And inside I am limited by the width of the wall so I could not build a proper second bell there.
The second brick box has 4 horizontal chambers.
The first horizontal chamber on that path has about the same CSA as the flue. The second one is about 3 times the CSA, the third one is 2 times and the last one where the flue will seat on top is same as CSA. There is no rationale behind it but I thought making the chambers a bit higher would slow down the gases like in a bell.
I fired some paper in the box directly at the port and had a bit of smokeback for a few seconds but after that I could have a draw even without chimney. So can't wait to see how it is going to perform when the chimney is added.
If not I will have to think about something else.

15mm steel would be quite expensive here in NZ and also quite heavy to put and remove. Any other alternatives? Would that work if I add some reinforcements to the 1.5mm stainless steel plate instead?
I have seen on one of your videos that you caped the top with angle steel and bricks. But I would like to be able to remove the top easily.
 
Graham Chiu
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Nono Junang wrote:

Graham Chiu wrote:Has the Far North District Council required any particular documentation from you for this build?



Went there to talk about the system, but could not find someone who understands what I am planing to build. Best bet would have been to find an engineer that would stamp it, but then that would just drive the costs.
So I decided to build it and document each step, test and refine it to ensure that it meets the National Environmental Standards for Air Quality and then take care of the paper work later with all my test results and documentation.
The bricks are all mortared with lime mortar, so easy to dismantle and tweak.



Well, I had a wood burner installed recently and this was from a major manufacturer.  I had to do the building consent myself and it's a painful procedure even with all the manufacturer's documentation.  You need to look at the consent forms to know what you have to be able to document, and I'd be surprised if the Council don't require that an engineer goes over your design, at your cost.

But in particular, you have this obstacle to overcome

Confirmation the appliance is approved for use under the National Environments Standards AS/NZS 4013, AS/NZ4012 - refer to the Ministry for the Environment.



https://www.fndc.govt.nz/services/building-consents-and-information/Guidance-Notes-for-building-in-the-Far-North/solid-fuel-appliances

I'm not sure how you propose to get your RMH approved for use.  Better to find out now than later.
 
Nono Junang
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Graham Chiu wrote:

Nono Junang wrote:

Graham Chiu wrote:Has the Far North District Council required any particular documentation from you for this build?



Went there to talk about the system, but could not find someone who understands what I am planing to build. Best bet would have been to find an engineer that would stamp it, but then that would just drive the costs.
So I decided to build it and document each step, test and refine it to ensure that it meets the National Environmental Standards for Air Quality and then take care of the paper work later with all my test results and documentation.
The bricks are all mortared with lime mortar, so easy to dismantle and tweak.



Well, I had a wood burner installed recently and this was from a major manufacturer.  I had to do the building consent myself and it's a painful procedure even with all the manufacturer's documentation.  You need to look at the consent forms to know what you have to be able to document, and I'd be surprised if the Council don't require that an engineer goes over your design, at your cost.

But in particular, you have this obstacle to overcome

Confirmation the appliance is approved for use under the National Environments Standards AS/NZS 4013, AS/NZ4012 - refer to the Ministry for the Environment.



https://www.fndc.govt.nz/services/building-consents-and-information/Guidance-Notes-for-building-in-the-Far-North/solid-fuel-appliances

I'm not sure how you propose to get your RMH approved for use.  Better to find out now than later.



We live in a rural setting, so when time comes I plan to approach it as if it was an open fireplace. We'll see.
I think it would be easier to approach council with a working system they can see rather than something on paper. And yes I know the pitfall with having to have everything certified by an engineer. We built a strawbale house and lots of our money unfortunately went into engineer fees. It is a pity that even for common sense stuff you have to go an see an engineer.
 
Graham Chiu
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Nono Junang wrote:
I think it would be easier to approach council with a working system they can see rather than something on paper. And yes I know the pitfall with having to have everything certified by an engineer. We built a strawbale house and lots of our money unfortunately went into engineer fees. It is a pity that even for common sense stuff you have to go an see an engineer.



Well, good luck on that.  If you do manage to get it certified then it would pave the way for other RMHs in NZ.  The question was asked before if anyone had succeeded in getting a RMH installed in NZ and so far there has been no one coming forward to say that they had.
 
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