6 inch J rocket stove from firebrick - a pattern to place them?

Hi,

I am trying to build a rocket stove/s for a stovepipe water jacket and for thermal mass in a greenhouse.  

I have pulled out a pile of fire bricks I got years ago, and am wanting to make a 6inch rocket stove as most of my salvaged pipe is 6inch.  (I do have a smaller amount of 8 inch, so could make a small bell style thermal mass).

75 that are 9 x 4.5 x 3in   or 230 x 115 x 75mm.
I can also get these insulating fire bricks the same size on sale, so if I can keep with this size all the better.
https://thermalnz.co.nz/insulation-brick-jm28.html

5 (two with corners cracked) that are 11.75 x 11.75 x 1.5 inches or 273 x 273 x 37mm  I can't find more of these size online.
12 x 12  x 2 and 13x 13 x 2 inch fire bricks are available, but at $33-46 each compared to $7 each for the other ones.

I have found a few photos of people making J cores with these bricks, but no clear pattern of how to place them.  I am sure it must be out there someone.  Anyone got a link?

Thanks in advance.

I think both of these can help with your build.

This link is to a nicely documented build using hard clay fire bricks 9"x4.5"x2.5" so about 7"x7" riser.  You 9"x4.5"x3" bricks will make a 6"x6" riser when you use the same pinwheel  on edge pattern.  

Pix:
https://permies.com/t/89382/a/70004/4E35A1E4-D63B-4D74-8889-DCBE4F386121.jpeg

From post:
https://permies.com/t/160/89382/RMH-Builders-guide-build-pic

Note:  Uncle Mud did a webinar on greenhouse RMH's:
https://permies.com/w/208519/Heating-Greenhouses-Rocket-Mass-Heaters.

Hope that helps.  Tom

Hi Annie,
I think you'll be able to build a RMH with the bricks you have.

But in order to help you find the right one, please explain a bit what use it's going to have.
A rocket stove is used for cooking.
You mention heating a greenhouse and a water jacket?
For a water jacket you need high exhaust temperatures, a RMH doesn't provide that as the heat stays in the mass.
In a greenhouse you might want to build a batch box that doesn't require feeding wood every 15-30 minutes.

Benjamin Dinkel wrote:Hi Annie,
I think you'll be able to build a RMH with the bricks you have.

But in order to help you find the right one, please explain a bit what use it's going to have.
A rocket stove is used for cooking.
You mention heating a greenhouse and a water jacket?
For a water jacket you need high exhaust temperatures, a RMH doesn't provide that as the heat stays in the mass.
In a greenhouse you might want to build a batch box that doesn't require feeding wood every 15-30 minutes.

Hi,  
I have two things I want to do.  One is to make hot water to put under the floor of my pier and beam house.  (The pex piping is already laid under it, and covered with insulation.)   I discuss this water jacket here:  https://permies.com/t/379218/Bricks-insulation-firebox

The second is to heat a small commerical greenhouse.  For both of these the wood heat is a final backup when there is not enough sun to charge the pass solar heating / thermal mass and solar water heaters.

The house floor is 35+ year old plysheet, and I will not be making a rocket stove/thermal mass in the house. I could put it in a separate bathhouse shed, but  when I do heat the water with woodfire is also often likely to be when the greenhouse could use the immediate heat from the rocket stove drum, and so one option would be to put the rocket stove and water jacket in the greenhouse and pipe the water back to the house. (This build pumps water 100ft in much colder temperatures, so it should work for me with no more than -3C  frosts.    https://www.builditsolar.com/Projectss/SpaceHeating/SolarShed/solarshed.htm)

I had wondered about a  6 inch with the focus on heating water and an 8in with a focus on heating a thermal mass.
I do plan to put pipes for pumping warm water into my greenhouse garden beds, so I could use extra heated water for this.

The water jacket is a 6 inch width, so it needs to be run with 6inch fire box.  
For this reason I may also want the increased burn of an 8 inch rocket stove / thermal mass to keep an area of at least 100 square meters heated up to 15C differential.