Retention heat combined with L style rocket stove.

I have made this to test an idea of mine that I can use heat retention with my L style rocket stove.  

Because the pot is so well insulated it boils water in a very short time ( how long I need to time )...   I used far less wood than previous burns when the pot was just open.


I believe if I was to insulate this after it heats up this concrete it would be cooking for a long, long time..   I am also considering making  a top for this that would allow the heat to escape in vents all around but keep the lid hot as well ...  I probably could have an oven on top of this...   The heat that was coming out around the pot was intense, but the burn was clean no smoke.

After 2 hours the temp of the outside of this mass was still at 120 degrees while the other cement was at 105.    I consider that amazing for having no insulation, and as large as the mass is.

Nicely done.
The concrete acts like a "pot skirt" and it's a theme mass.
What kind of mix did you use?
Did you include perlite?
Portland cement is known fail at higher heats,  though people have had better success with mixtures that include anticracking fibers.
Of course this isn't a RMH,  it's a cooking rocket stove,  so it probably doesn't get to those crazy high heats anyway.

William Bronson wrote: Nicely done.
The concrete acts like a "pot skirt" and it's a theme mass.
What kind of mix did you use?
Did you include perlite?
Portland cement is known fail at higher heats,  though people have had better success with mixtures that include anticracking fibers.
Of course this isn't a RMH,  it's a cooking rocket stove,  so it probably doesn't get to those crazy high heats anyway.

There was about 5 bag of quickcrete concrete I picked up for 1/2 price  so I grabbed them but did not realize that does not work with air crete so I wanted to do something with them...


I only ran this 30-40 min and the outside wall was getting to the point I did not want to keep my hand on it....    If I gave this a full hour then it really would of gone crazy for heat...

I used pure cement so that baby is HEAVY, so a large thermal mass it is.


What shocked me was how little wood it took to boil 5 cups of water,  the sides of the pan were so hot that when i sloshed water on the sides they instantly vaporized the water...

I am trying to figure out how I can slow this process down...    I considered a stick inside a pipe that would feed into the chamber at a given rate....     If the feed rate could be regulated then it seems to me I could get an even burn and tame the monster :-)

It does get crazy high heat because it has ceramic fiber on the inside  which gives me like 12 inch long flames...

Oh yeah the 126 degree on my gun was like 2 -3 hours after the burn from the outside of the mass...

Oh yeah,  you use the 5 minute riser right?
Very advanced.
The destruction of cement by heat might be addressed by wetting it after burns.

Auto feeding the fire is a great idea.
DIY, making a spring powered feeder has the problem of arranging for consistent force, so I've often thought ana arrangement with pulls and a weight might be best.

Tested my boil time of water.

30 min    40 cups of water ( 2.5 gal ) to rolling boil.



I think as long as I have water in the pan the cement top should last a long time because most of the heat is being captured in the water.    

I have a crack in the cement from the first run,  I think I will get wire and wrap the outside with it to help it maintain form.

30 minutes is the fastest I think I have ever heated 2 1/2 gal to boiling    I will have to give it a test on stove inside.

I did another test burn with the pot in. Still boiled the water under 30 min and the stove hit 250 deg in 30 min while the water was at rolling boil.

Any chance of pictures of your 5 min riser? Did you use rigidizer?

Just getting too the build point

Toby Ornot wrote:Any chance of pictures of your 5 min riser? Did you use rigidizer?

Just getting too the build point

Hi Toby,

I have another thread where I detail the riser, but it is nothing more than this.

https://www.amazon.com/gp/product/B014V9J4PM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

On the outside of the riser I used sheet aluminum then I used short wire to keep it in the form of a tunnel.

On the inside of the riser I coated it with sodium silicate ( water glass ) to keep the ceramic fibers in as they are not a good thing to breath.

Mind you I think I know of one other doing what I am doing so this is highly experimental  I often venture out past where few have traveled. ...