• Post Reply Bookmark Topic Watch Topic
  • New Topic

EZ No Tools Brick Micro Batch Box Core (The Match Box) Plus Variations  RSS feed

 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
i have come up with a sweet little batch box today!  im very happy with this idea ive come up with today, and ive come up with at least 5 variations of this new lego idea ive had.  no tools or cutting required to make the core, hopefully.  just stackin' blocks, and mortar.   ive made a video of dry stacking and show'n'tell on my micro-batch idea, and ive done step-by-step photos of the concept/build (dry stacked)



what do you think, guys?  i will post the steps and photos as soon as i get some time later on
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
update, i love this thing so far.   i should have tried fire-bricks a long time ago

cold test fire video


rocket stoves episode 40 Match Box exhaust comparison


episode 41, dense brick mass retaining heat
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
im trying to post the step-by-step photos to build this core, from my iphone, but this topic/thread doesnt even show up when i use my iphone.   i have to use it to post the step-by-step photos.   is this thread on public probation for some reason?   why cant i find this thread from my iphone to upload pics for you guys?  any help please anyone?

thanks
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
After some confusion between "rocket stoves" and "mass heaters" forum categories, here are the step by step build photos, dry stacked before the test fire.

I will have a small mass on this stove eventually
image.jpeg
[Thumbnail for image.jpeg]
Step 1, floor
image.jpeg
[Thumbnail for image.jpeg]
Step 2, floor and sides
image.jpeg
[Thumbnail for image.jpeg]
Step 3, back wall
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
More steps to build.
EZ, no cutting! 
image.jpeg
[Thumbnail for image.jpeg]
Step 4, match box top
image.jpeg
[Thumbnail for image.jpeg]
Step 5, first riser row
image.jpeg
[Thumbnail for image.jpeg]
Here is one of many variations with double thick box top.
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Nothing going on that I can see, everything looks normal. Phone access may just be wonky or something?


Ah, you were uploading while I was writing. Different forums would make it harder to see the thread
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
So far, you have a nice L-tube rocket (which would benefit from a grate to hold the fuel up as you said); it is not a batch box at this point. A batch box by definition is designed to be filled with wood, lit and left alone to burn down. To be effective, it needs a constriction ("port") between the firebox and the riser. Peter van den Berg has done the research, testing dozens of variations, to find the best proportions and configuration for this. So if you desire to make a batch box, just follow his recipe and be assured that it will work well. No point in reinventing the wheel, and you are not likely to make something better without more dozens of variations, and strict numerical testing to be certain of results.
Peterberg batch box dimensions
Now finding new ways of stacking bricks to make the dimensions in the table is a worthwhile endeavor.


 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
i could fill it and walk away, but i dont have a door yet.  the feed or "box" is way bigger than the CSA of the riser, as i designed to hold extra fuel, not the same CSA like a L-tube should be.   i consider it a match box, or mini batch.  but whatever it is, im really happy with it so far.

i agree it needs a little restriction between the riser and and box.  something i could likely easily remedy. 

it sure does need a burn grate above the floor, and that is something i could also easily do myself.

i wanted to share how convienient it is to not have to cut any bricks, and how compact and simple this core is.  and share the plans/idea with you in hopes of input/expert advice.  do you think i should mortar it together?  i dont feel like im wasting my time, and i really like this one, aside from the unfinished door, grate, venturi, and another stack of riser bricks.
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I just mocked up a 4" batchbox and riser with uncut firebricks (mostly splits) that follows the published proportions pretty closely. I have to leave now, but will test it and get photos later tonight.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
That is AWESOME Glenn.   keep me updated!

i truly appreciate all the help and support on these projects!  i also have a few updates from today.  i made a longer variation of this burn box, and a temporary door, and an elevated burn grate, two more test fires, and one is burning as we speak.  i also made a couple videos and photos along the way. 

here is Ep#42 variations


here is ep#43 baby batch temp reading


i have more but i need to upload them
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
here is two more videos from today's 4" variations testing.  im excited to see your 4" brick batch also Glenn! 

im quite pleased with using fire bricks to build the core.  keep in mind, these tests im doing are only using temporary riser pipes and dry stacks.  later i will add a taller proper brick riser and mortar it all together after I iron-out the kinks, so to speak. 

here are episodes 44 and 45 in my rocket stoves series


Ep#44


Ep#45

 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
The batch box I put together has a firebox 6" w x 9" h x 13 1/2" long, a port connecting it to the riser 2" w x 4 1/2" h, and a riser 3 3/4" x 4 1/2" x 27" h. The firebox width (6") and the port width (2") are easily adjustable.

I wired the riser bricks together for stability. There is no insulation, but gaps are narrow. The square riser is not ideal for continuing the turbulent vortex, but is adequate.

I lit the fire with a few twists of paper and cardboard, followed by thin bits of scrap lumber. Once the kindling was going well (2-3 minutes), I filled the firebox and bricked it up with a gap of 1/2" to 3/4". The full loads were old weathered but dry scraps from 1x1 to 2x4, mostly 12-13" long. It took several minutes for the full load to be burning, but then flames often reached the top of the riser or 8" higher. After the first load burned down to coals, I reloaded, and then reloaded a third time. With the riser preheated, I got the cleanest view of the double ram's horn vortex from the port into the riser. This has been observed by researchers to be the best turbulent mixing effect.  The fire finished burning before reaching the top of the riser. During the third load, I stood with my nose 4' above the riser and breathed in the exhaust deeply and comfortably. It had no particular smell and was not objectionable in any way.
IMG_1234-w600.jpg
[Thumbnail for IMG_1234-w600.jpg]
first assembly - riser gets another course
IMG_1236-w600.jpg
[Thumbnail for IMG_1236-w600.jpg]
interior firebox and port
IMG_1241-w600.jpg
[Thumbnail for IMG_1241-w600.jpg]
first kindling fire
IMG_1248-w600.jpg
[Thumbnail for IMG_1248-w600.jpg]
loaded
IMG_1283-w600.jpg
[Thumbnail for IMG_1283-w600.jpg]
overall view while burning
IMG_1293-w600.jpg
[Thumbnail for IMG_1293-w600.jpg]
looking down riser - double ram's horn vortex
IMG_1294-w600.jpg
[Thumbnail for IMG_1294-w600.jpg]
vortex 2
IMG_1296-w600.jpg
[Thumbnail for IMG_1296-w600.jpg]
vortex 3
IMG_1301-w600.jpg
[Thumbnail for IMG_1301-w600.jpg]
firebox front in operation
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
For reference, the official table dimensions for a 4" batch box are:
Riser: 4" diameter x 29" h
Firebox: 5 3/4" w x 8 5/8" h x 11 1/2" deep
Port: 1 7/16" w x 6 5/16" h

My dimensions are the closest I could get using uncut firebricks. Most of them are a hair larger, while the port had to be a bit shorter and wider.

Round or octagonal are the ideal shapes for a riser; square is less effective, while strongly rectangular is bad. The more it differs from round, the larger the actual cross section needs to be to compensate for drag.


Edited to correct an error that came from the copy of the chart I used. The port height is supposed to be 6 5/16" high, not 5 5/16". (That chart has now been corrected.)
My port after some final adjustments in the dark ended up only about 1 1/2" wide; next run I will widen it to 2" to see what difference it makes.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
good work Glenn!

  i really like it. that sure is a great ram-horn in there.  good job with the riser venturi.   thats the one thing im still lacking.  

   after building 3 rocket mass stoves, and studying for a couple years, i think the brick one is going to be the one i finally actually use in my dwelling.  of course the core would be surrounded in cob or clay bricks or something to support a barrel heat exchanger.  

  would your 4" batch accept one more brick for length for burning longer pieces?  i understand you want to stick with certain dimensions, but im curious about larger pieces of wood in length...

   so far im excited.   im going to actually use/install one of these brick designs soon, and tomorrow is my 30th birthday lol. 

    do you have any input if someone were to build one these in their home?  seems safe and clean and reliable, i think after its all mortared together and surrounded in more bricks or something for structure and mass it would work.   i just wanted to be sure about the 4" exhaust.

   thanks again Glenn





 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
My firebox is already 2" longer than the table calls for at this system size, but it might work alright to add another brick in length. I can't try it now, it's raining this morning. But the layout should be easy enough for you to exactly duplicate, and then you can try it out.

The system components are sized the way they are because those ratios have been found to work best. They are mostly not critical, as long as say the port area is in the correct ratio to system area. That and air intake area matter a lot. If the firebox was much larger, there might be too much wood pyrolizing at one time for all the gas to be properly combusted in the riser.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
local weather calls for rain here today also in SE ontario canada.  

   if i had more bricks, which i plan on getting some more this weekend, i could try more variations.   i had a great idea to make a venturi inside my core but it would involve possibly splitting one brick to centralize the opening.   also i could duplicate your 4" peter-berg riser layout.  i am excited to work with the brick design and install one in my tiny 20x20 concrete earthship dwelling, possibly this year.   my dwelling already has a nice tall 4" double wall B-vent stack and thats why i am experimanting with 4" exhaust, plus a tiny home doesn't need anything much larger.

   a little more R&D and i think it will happen.   i really want to use a "grease drum" barrel for a bell but they seem hard to find.   ive heard they are available in stainless steel.  What type of bricks or mass can I put around this core?   Clay or cement bricks around the outside for mass and barrel support?

  thanks again Glenn
 
William Bronson
Posts: 1322
Location: Cincinnati, Ohio,Price Hill 45205
14
forest garden trees urban
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Since grease barrels are hard to find,consider a scrapped water heater.
The walls are nice and thick.
Electric water heaters will be easier to adapt,as they have no central pipe to worry about.
Another potential barrel might be a file cabinet. Thinner metal,but worth a try.

I would consider using cement block to support the "barrel",but lining them with a layer of cob,to protect them from the heat.

 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
william
thanks for the input.  i did consider a hot water tank bell, but thats more "fabricating".     im no stranger to fabricating and such but i also crave stainless steel, which some water tanks are.  id prefer a stainless drum but i dont have one, or alot of money.  square cabinets would work but thats more fab work to seal and remove paint. 

anything stainless shouldnt involve removing paint, or painting with hi-temp, and looks nice in my opinion.  i will get some type of regular brick to surround the entire core for mass, and to support the bell/heat exchanger.  i am planning on buying more bricks and supplies this weekend or tomorrow afternoon, but im still on the hunt for a heat exchanger/bell.   i do have hot water tanks if i cant find something more appropriate, like a drum barrel

these are the bricks im considering buying to surround the core
https://www.homedepot.ca/en/home/p.mini-beltis-wall.1000760229.html
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As long as you don't use those near the top of the bell, unless lined with cob or something heat resistant. They are cement-based, and will start to spall or disintegrate at riser exhaust temps.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
i only plan on using them around the outside of my firebrick core, not up top, nor in the falme path, but simply surrounding the firebrick for a larger base/mass and to support the bell/heat exchanger.  these are labeled as stones but they could be concrete
 
Satamax Antone
gardener
Posts: 2240
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
54
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John, for the radiator i've had good luck with home heating fuel tanks. Even galvanized ones. As they don't offgas before 600c or more. As well as having more surface than a barrel.
 
Peter van den Berg
gardener
Posts: 506
Location: +52° 1' 47.40", +4° 22' 57.80"
60
forest garden trees wofati woodworking
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John,
A 55 gallon open top barrel with lid is about right to serve as the radiator for a 4" batch box, grease drums are way too small. The chimney pipe can be entering the barrel simply through a hole in the top somewhere around the perimeter, reaching down to just 4" or 5" above floor level. This way, you don't need elbows as the pipe is already vertical. I've built this construction 3 times now and it works. Satamax calls this solution a "plunger tube".

When you prefer a tiny mass heater, line the barrel with bricks at the inside, this will keep the maximum temperature at the outside down also. The top is good to cook on when the thing is running full tilt.

Just my 2 cents...
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
thanks Peter for your advice, i trust your experience and judgement.

  45 and 55 gallon drums are much easier to find around here also, so that would simplify things, but i am not likely to get a stainless one that size, which is okay.

satamax i can get galvanized garbage cans and flip one upside-down, but i am guessing the cook top will exceed 600 sometimes, causing off-gas.  i would love a stainless drum but i could settle for a 55 gal barrel.

ive ordered 25 more dense firebrick in bulk for 50$ today, and im going to get some of the other surround stones this weekend.

thanks guys for the help
 
Satamax Antone
gardener
Posts: 2240
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
54
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator


John, i think i can say, i started following Peter's research quite early. I don't know for sure if the green machine i built, wasn't the first batch following Peter's research and publication of dimensions, after Canyon and Donkey's.

After this, i built a barbecue with the batch's system. Then the range retrofit. Then following this, i did my workshop heater.

http://donkey32.proboards.com/thread/1817/starting-build-220mm-rocket-double

This is a nearly "by the book" build. And, it never ceases to amaze me. Not absolutely perfect. But not far. It's been back to work for a few days, with my latest mods. And there is few modifications i could wish for.

My latest opinion on the subject. Do a first bell above the riser, out of mass, instead of a barrel, to store the bulk of  high heat, instead of releasing it in the surrounding atmosphere, then, use a cooktop, or metal bell, to further cool down the gases, to exhaust temperature levels. Rather than the other way around. And use a door in this bell above the riser, to make a black mass oven. So youhave nearly all the advantages of this system. To cook on a faster cooktop, i added cast iron plate above the firebox. Instead of insulation. But when not in use as a cooking apparatus. I cover oit with bricks. So i would have the best of all worlds. Quick cooking, a fast heat bell, with heat storage oven. Then a quick heat metal radiator, and simmering plate. Prety efficient in all of it's aspects, i would say.

Hth.

Max.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
well i just got home from shopping, i ended up finding smoother and cheaper stones in-store, and i didnt like the other ones when i saw them in person.

i came home with:

75 of these
https://www.homedepot.ca/en/home/p.range-red-cobble---lite-paving-stone.1000402082.html

4 of these
https://www.homedepot.ca/en/home/p.natural-diamond-patio-paver---24-inch-x-24-inch.1000402077.html

and one big fancy-pants bucket of dry hi-temp mortar
http://www.rona.ca/en/high-temperature-mortar
 
Satamax Antone
gardener
Posts: 2240
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
54
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John, one word of caution, i can't see what pavers, or paving stones you bought. Can't seem to access home depot canada at all.

But if they are anything non refractory as i imagine . Careful, not to put these in a place where they would heat too fast. I have had a concrete or some type of tough clay pipe, meant for sewage, explode in one of my experiments. The bang was impressive. Thankfully, it was surrounded by insulation and a metal pipe.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Wow, that's crazy.
Like I said before, these paver stones are only for external mass, and will only be outside the firebrick.   The core and flame path will be made of refractory fire brick, as I've shown in my videos.  I will not place the pavers in the flame path or anywhere too hot.   They will go around the outside of the firebrick to support the structural integrity and to absorb a small amount of heat.   The exterior pavers are labeled as concrete.  Labeled as 1.8" thick, 7.9" tall, and 4" wide each.  it is safe to say they are 4x8x2".  I got 75 of those, and I got four 24" X 24" slabs, 1.6" thick.  Here's photos, if you can't see the Canadian web sites.

image.jpeg
[Thumbnail for image.jpeg]
75 pavers, two out of four slabs, mortar
image.jpeg
[Thumbnail for image.jpeg]
This mortar is supposed to be one of the best around here for heat rating dry mix
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
When I find my favorite variations I will mortar it together in its final resting place, with multiple layers beneath, plus it will all be resting on a concrete floor, in a semi-underground building with concrete block walls.   I have ordered a pack of 25 more firebricks and I'm waiting on them to complete my riser and variations.

Questions:
  Is it okay to surround the firebrick core like this with these concrete pavers?  It doesn't seem to get very hot on the outside but I haven't done a long burn test yet. 

What is the optimal air/fuel ratio?    If I know the optimal AFR I can make the proper sized air opening in the front door.

Thanks guys

image.jpeg
[Thumbnail for image.jpeg]
They fit nice...
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
The pavers in contact with the firebrick core may get too hot for safety, but more importantly they will wick heat from the firebox. You want a couple inches of perlite-clay or other insulation all around the core before you put the pavers on. (Or put the pavers up with a gap and fill the gap with insulation.)
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I second Peter's suggestion of a steel barrel bell lined with bricks around the sides as an easy and effective mass. If you can find a barrel with removable top, you can cut out the bottom to fit the core, line it with bricks, and have an easily removable top for inspection.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
well, i was hoping to use the concrete pavers against the core for structural integrity.  but if they wont last maybe i should have a layer of insulation between, but that would ruin the structure assistance, and the thermal conductivity i was hoping for into the outer concrete "mass" bricks.

  perhaps i should do a few long burn tests, which i have not dont yet on this core, or the concrete bricks.  i was talking to a YouTube'r yesterday and he said he had used 80 psi concrete and vermiculite in his core and he said its lasted over one year so far.  i didnt know concrete was okay in a cast core.  i asked him for updates because its hard to believe.  i can certainly do a long burn test when i get the rest of the firebricks this week for a little more R&D...

  thanks for the help Glenn,
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I doubt anything short of actual hard use would show the limitations of the pavers against the core, unless they actually spall explosively. A good well-packed perlite-clay mix would give enough backing that the firebrick core wouldn't shift to speak of. Ones I have made have been quite strong as long as they are well contained outside. You could have scattered solid mortar tongues to rigidize the core, with the great bulk of the gaps filled with insulation.

Regular concrete will overheat and disintegrate on its inner surface, but if the heat does not reach proper RMH core temps, it may be mitigated enough by the vermiculite that the damage doesn't progress fast.
 
Peter van den Berg
gardener
Posts: 506
Location: +52° 1' 47.40", +4° 22' 57.80"
60
forest garden trees wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John McDoodle wrote:What is the optimal air/fuel ratio? If I know the optimal AFR I can make the proper sized air opening in the front door.

Air inlet opening is calculated by using the cross section area of the riser. Total air inlet is 25% of riser cross section area, when using a p-channel this would be 20% for the main inlet and 5% for the p-channel. To use the proper csa you need to realize the square riser isn't as effective as a round one. The square one need to be larger in order to compensate for the drag in the corners. In practise, a circle with a diameter the same as one side of the square are comparable aerodynamically.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Peter,
thank you again, that is exactly the info i was asking for.  My riser is already slightly oversized to compensate for the shape, and my exhaust will be 4" round.  If square CSA flows similar CFM to round of the same diameter, then my square air intake should be (4x4) 16 divide by four = 4 square inches?   that sounds almost perfect, i could make the intake one-inch-high and four-inches wide in the bottom of my front door, which would be fine with me.

Glenn,
would a thin air gap (like under ceramic floor tiles) in the hi-temp mortar/plus the hi-temp mortar protection itself work between the brick and the firebrick?
i mean i could add perlite to the mortar but thats questionable lol.

can either of you explain whats between the core and the surrounding bricks in this batch, which Paul explains in this video, was built by Peter?  im curious what is between the surrounding brick, and the firebrick at the 7:00 minute mark in the video below, from wheaton labs auditorium.  it looks like concrete board between the firebrick core and the surrounding bricks, but everyone tells me concrete is bad?  but just because it looks like concrete board does not mean it is, i suppose. 

can anyone tell me the building materials used in the batch unit at the 7:00 mark?  the material between the core and the brick surround?


my new shipment of 25 more firebricks should be in this week by thursday

thanks in advance for the info
 
Peter van den Berg
gardener
Posts: 506
Location: +52° 1' 47.40", +4° 22' 57.80"
60
forest garden trees wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John McDoodle wrote:Peter,
thank you again, that is exactly the info i was asking for.  My riser is already slightly oversized to compensate for the shape, and my exhaust will be 4" round.  If square CSA flows similar CFM to round of the same diameter, then my square air intake should be (4x4) 16 divide by four = 4 square inches?   that sounds almost perfect, i could make the intake one-inch-high and four-inches wide in the bottom of my front door, which would be fine with me.

John, that's not quite what I meant, must be the language barrier. When you have a square riser you just pretend it is a round one which fit inside the square riser exactly. So calculating the air inlet from this would be radius 2 multiplied by itself and Pi = 3.14 square inch.
John McDoodle wrote:can either of you explain whats between the core and the surrounding bricks in this batch, which Paul explains in this video, was built by Peter?  im curious what is between the surrounding brick, and the firebrick at the 7:00 minute mark in the video below, from Wheaton labs auditorium.  it looks like concrete board between the firebrick core and the surrounding bricks, but everyone tells me concrete is bad?  but just because it looks like concrete board does not mean it is, i suppose.

This is calcium silicate board, otherwise known as Duraboard, the same material as the make-shift door.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Peter

i can not thank you enough for your support and your time with this help and information.  Dank Je. 

...Your english is likely better than mine is, so i doubt it is the language barrier lol.  Thank you for correcting me on the intake size.  after i wake up from my coffee i will try to understand it better.  i am currently sick, fighting a bad head-cold or flu virus and i will blame it for fogging my brain

i think i can access some duraboard locally, if that is good to use between the core and the paver bricks?

have a good day guys
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Today I tested 2 things in a short test,
Concrete bricks, Venturi at the bottom of the riser/back of firebox.  
The only conclusion I reached today was a semi-smokey burn.   I didn't get to do any concrete testing because the concrete brick I used to create the Venturi, caused nothing but problems.   The smokey burn today was devistating to me, because I never have dirty burns. 

The unclean burn was from one of 3 possibilities.
1 concrete Venturi brick too cold
2 Venturi misplacement
3 bigger than usual air gaps

I had bigger gaps around this test with dry stacked bricks, I tried to use aluminum tape and Tetris to fit the blocks together tight, but there were some gaps.  

If I remove the Venturi brick, everything should go back to normal, or maybe I should be using a firebrick?   But I wanted to test the concrete block to see how the heat would affect it.

Here is a quick sketch from above, where I show the placement of the problem brick.   I thought it would create a Venturi and make it better, but it was much worse and slightly smokey.  

image.jpeg
[Thumbnail for image.jpeg]
From above, the blue marker is the riser, the red is the problem block placement I used
 
Peter van den Berg
gardener
Posts: 506
Location: +52° 1' 47.40", +4° 22' 57.80"
60
forest garden trees wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
John,
The venturi should be in the middle, not at the side. And the riser shouldn't be a rectangle, preferably. When you need to use a rectangle, turn it around 90 degrees so the shortest side is facing the firebox. What you did is using the worst configuration, I found out 4 years ago. Air gaps all over the place isn't also doing any good, too much random air.

Best to mimic Glenn's setup, this will work.
 
John McDoodle
Posts: 520
Location: ontario, canada
fungi tiny house transportation
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I believe my unclean burn was because of the air gaps and cement brick Venturi. 

I wanted to finish the research and development before I mortar it together, which will completely eliminate the air gap problems.  I'm also waiting for my new bricks before I mortar the gaps, the bricks should be in tomorrow, or so I'm told. 

I will try Glenn's variation next, but i need a closer look at his riser configuration.  

I did get my original unit to burn clean again by simply removing the cement Venturi.  

I'm concerned about a trying a tiny square riser but I will try I it.  So far my original unit burns clean with the original configurations.  I think adding the concrete Venturi caused my only problem so far.  

I'm super excited for my new bricks to come in tomorrow, and I'm getting a new chainsaw today.  Only to cut dead elms, not living trees

Thanks.  
 
Glenn Herbert
gardener
Posts: 2144
Location: Upstate NY, zone 5
73
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
My riser configuration is combined with the venturi port. The port has two bricks horizontally at the bottom, leaving a 2" x 4 1/2" gap between them. (I actually found after the burn that the gap got narrowed to about 1 1/2" wide, and still worked well.) Then another horizontal brick centered above them to complete the 9" high back wall of the firebox. The far face of these bricks is the near face of the riser interior.

The riser is simply made from bricks standing on end, almost corner to corner, to make a 4 1/2" x 4" more or less space. The narrow dimension of the riser is the port and the opposite side. The bottom course of the riser is three bricks standing on end plus the port assembly. Each course above that is formed of four bricks on end. Look closely at the "overall view while burning" photo in my post above.
 
And then we all jump out and yell "surprise! we got you this tiny ad!"
Thread Boost feature
https://permies.com/wiki/61482/Thread-Boost-feature
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!