J-tube bricks: making my own

i have a couple of questions and i find partial answers to them in other threads, but nothing comprehensive.

i live in alaska and with the exception of basic concrete bricks, there just arent any. there isnt a brickyard in the entire state that i am aware of.

so, being that i want to do this project right, i am considering making my own bricks for my j tube.

if it is possible for me to do so, what size bricks would be best to build my 8 inch system?

also what is the best mixture to make these bricks?

im assuming i should use fire clay, perlite, and refractors cement?

if these ingredients are not correct let me know, and also what amounts should i be using of each in my mixture?

anyone who can help me out here please let me know,

thanks in Advance,

Troy

Troy Fairclough : there are Two major and often conflicting opinions of what makes a good fire brick, Heavy/Dense, and Light F Bricks, add in a confusion of
exactly what 'Fireclay' is - and its major attributes , and it would take several books to begin to be Comprehensive !

A Good source that I send people to www.traditionaloven.com/articles/101/ This explains fire clay, which can be 'cut' with local Clay !

Heavy Fire Bricks - - - - - - - - - - - - www.traditionaloven.com/articles/84/ Note that ovens and kilns use heavy (sometimes both) nearly every time

Light Fire Bricks - - - - - - - - - - - - -www.traditionaloven.com/articles/81 These bricks have a place in RMHs and are my personal favorite


If you goto> the listing of Rocket Stoves 'recent topics' you can scroll down to and click on> "Fake Fire Brick" and then read Erica Wisners Thread Extension
which is nearly comprehensive and more accurate than my earlier posts which contains some errors !

After reading through this material the only thing left to do is find Your preference, you will never go far wrong if you agree with Erica (or Ernie ) Wisner !


There is Also the idea of making the Feed Tube and the Burn Tunnel out of one Monolithic Pour, many people have had good luck with this, you can goto>
the Permies Toolbox at the top right of this page, click on search and do a Permies only search for Articles on Castable Cores, a good search window would
be from 2 years ago to 6 months ago !

-Have you been to rocketstoves.com to download a PDF Copy $15., of "Rocket Mass Heaters'' ? This is 'The Book' that most of the over 100,000
RMHs have been made from ! And I don't make a dime !

It allows us to use a common language to describe the same object and its shapes, dimensions, and characteristics, especially as they then relate to their
assembled partners !

For the Good of the Craft ! Big AL !

Late note : While a Portland cement type should never be considered for inclusion in any part of the RMHs combustion Zone, you are actually near a hot bed
in research in other Cements/Concretes. The Cold Climate Housing Research Center, an arm of The University of Alaska, Fairbanks, is doing much research in
this area, and deserves a look if only because virtually all of your Cement is coming from Korea and China ! A. L.

allen lumley wrote:Troy Fairclough : there are Two major and often conflicting opinions of what makes a good fire brick, Heavy/Dense, and Light F Bricks, add in a confusion of
exactly what 'Fireclay' is - and its major attributes , and it would take several books to begin to be Comprehensive !

A Good source that I send people to www.traditionaloven.com/articles/101/ This explains fire clay, which can be 'cut' with local Clay !

Heavy Fire Bricks - - - - - - - - - - - - www.traditionaloven.com/articles/84/ Note that ovens and kilns use heavy (sometimes both) nearly every time

Light Fire Bricks - - - - - - - - - - - - -www.traditionaloven.com/articles/81 These bricks have a place in RMHs and are my personal favorite


If you goto> the listing of Rocket Stoves 'recent topics' you can scroll down to and click on> "Fake Fire Brick" and then read Erica Wisners Thread Extension
which is nearly comprehensive and more accurate than my earlier posts which contains some errors !

After reading through this material the only thing left to do is find Your preference, you will never go far wrong if you agree with Erica (or Ernie ) Wisner !


There is Also the idea of making the Feed Tube and the Burn Tunnel out of one Monolithic Pour, many people have had good luck with this, you can goto>
the Permies Toolbox at the top right of this page, click on search and do a Permies only search for Articles on Castable Cores, a good search window would
be from 2 years ago to 6 months ago !

-Have you been to rocketstoves.com to download a PDF Copy $15., of "Rocket Mass Heaters'' ? This is 'The Book' that most of the over 100,000
RMHs have been made from ! And I don't make a dime !

It allows us to use a common language to describe the same object and its shapes, dimensions, and characteristics, especially as they then relate to their
assembled partners !

For the Good of the Craft ! Big AL !

Late note : While a Portland cement type should never be considered for inclusion in any part of the RMHs combustion Zone, you are actually near a hot bed
in research in other Cements/Concretes. The Cold Climate Housing Research Center, an arm of The University of Alaska, Fairbanks, is doing much research in
this area, and deserves a look if only because virtually all of your Cement is coming from Korea and China ! A. L.

i have purchased the book and am reading through it currently, and am mostly done allen, thank you

i have most definitely decided to cast my core, its seems like the most timely and efficient model.

https://permies.com/t/30654/rocket-stoves/Cast-Refractory-Cement-Combustion-Chamber i was considering using this design, with measurements from the book for an 8 inch system.

is the curve on the back of his J tube a good idea for efficiency? or a straight back model. i am mostly concerned with heat and fuel efficiency above all else.

also i have a few other questions while im here:

my exhaust pipes for under my thermal mass are solid steel. they are 4.5 inches in diameter,and 12 feet long. i am planning to use two of them which gives me 9 inches in total diameter and enough to keep the air flowing properly. i really feel that these thick steel pipes will be great for conducting heat into my thermal mass and they are indestructible. i am still unclear about my thermal mass and what i should or should not put into it for the most efficiency. i have acquired a rather large pile of broken concrete bricks and tons of pieces of busted up cinder blocks. are these remnants a good thing to take up space and help conduct heat in my thermal mass?

thanks again and i love the site and all the smart minds here.

hope the new year is great for all

troy.

Troy Fairclough : Time, Temperature, and Turbulence ! O.K., I got that out of the way, basically I Think we have enough redundancy in the system so that
often, with minor modifications to the system,we can get a secondary burn belching fire out of our Heat Riser !

This is not what I should be telling you Now, Now you should be getting the make your 1st Rocket Mass Heater RMH, as close to ''The Book'' as possible and save
experimentation for subsequent RMHs.

I have no handle on how much difference the upswept curve at the back of the Burn Tunnel start of the Heat Riser will make ! As this was Von Sommerfelts' Forum
Thread and we can ask for an update, this is more than good manners to send a P.M. asking for a follow up Thread/Thread Extension to his post to clarify his feelings
about this Cast Core and if he would do it again !

Before we get to the math of your proposed build, we have to talk about What is/is not happening at the surface of the 'skin' of the Horizontal Ducting in the Cob
Thermal Mass. Right at the surface there is an area of Non Flow, usually called the Laminar Flow effect, the fastest flowing gases (and the hottest ) are in the center
of the ductwork! Generally with an 8'' system the 30 + feet of horizontal run still manages to extract most of the heat energy!

So you want to build a 8'' system, Which should have a Constant Cross Sectional Area of ~50 ''~ ( pi X r2 ) , I under stand that you have some pipe with a nominal
4.5 '' size, inside/ outside was not given, and in order to make the math simple, lets say 4'' , so (pi X r2 = 13'' ), so 2 sections of 4'' or 4.5'' for even 3 sections will
not have a Constant Cross Sectional Area Large enough, but our problems don't end there !

Because of the Increase of the Percent of Surface Area to Cross Sectional Area available for Gas flow as we shrink the size of the pipe were are flowing gases
through -The Laminar Effect is compounded and Flow slows and stalls !

So - When we try to cut the size of the pipe we are flowing gases (or Liquid, or Plasma) through by 1/2, we are reducing the flow to a 1/4 ! Said another way, to
maintain an Flow equal to the flow of a pipe 2 Xs bigger we need 4 pipes !

Check with a Volunteer fireman, with equal pressure, and hose length, a 3'' fire hose will flow 4Xs the water of a 1 1/2 '' fire hose !

Do not use any Concrete/Urbanite in the Rocket Burner that is not well insulated from Combustion core, after your hot exhaust gases have left the Manifold area of
your rocket burner you can use all the Urbanite you have, remembering that the cob needs to be in complete contact with all of the Horizontal ductwork to both protect
the ductwork and the structural integrity of the Thermal mass, AND to promote the heat energy absorption by the Thermal Mass ! Outside of that, Heavy means more
mass, more mass equals more heat storage !

Keep coming Back, with ^ 21,000 fellow members world wide, you should be able to come here 24 / 7 and find someone who wants to talk about what you want to talk
about ! For the Good of the Craft ! Big AL