Shippable Walker 6" Superhot Cores now available

Hi All- I've spent a fair bit of time on this site poking around through the years and am so grateful for this community. I took an appropriate technology course with Tim Barker up at Wheaton Labs several years back and was very impressed with the various rocket stove experiments. A year ago I built a rocket stove in a greenhouse from fire bricks. While building it I came across Walkerstoves.com and Matt's plans for ceramic fiber cores (which were partially inspired by his collaborations with Tim Barker). I have since realized that, for me, ceramic fiber has some distinct advantages to fire brick. It is much more insulative, light and portable, and easy to cut and work with. Having made one for myself, I have decided to offer them for sale. They could really speed up rocket stove/heater projects by simplifying one of the more challenging parts of the process. I am pleased to announce that I am now ready to sell my first ceramic cores, shipped directly to your doorstep. They will come in a box, pre cut. You will need to simply assemble and pin together the pieces, which should take less than 30 minutes. The price is ultimately going to be somewhat higher, but I am offering my first 2 6" cores for $250 which includes free shipping to any location in the continental US. The weight is a little less than 25lbs. The (6) fire brick splits are not included. I can ship you some separately, although you can probably buy them from a local masonry supply store for a much better price.

Please let me know if you have any questions and if you are interested in purchasing one of my first two stoves. I also plan to offer 8" and batch box ceramic cores in the near future but wanted to start with the 6". The 6" is great for a rocket barrel oven, outdoor water heater, or in a rocket heater. These are not UL listed- any indoor use is at your own liability. Also- I am licensing the designs from Matt, so a portion of all purchases will go towards supporting him and further innovation on his end.

One great use for one of these would be to power a rocket barrel oven: https://permies.com/wiki/60370/Rocket-Powered-Oven-build-super

That sounds wonderful Luke! I wish you well on your new venture to make it easier for others to become rocket scientists.

Matt has some great designs. I am planning my kitchen around building a Walker Stove in the center of the room to be my main cook surface. I plan to have a gas stove for the middle of the summer and when I am in a hurry, but the Walker stuff is the way to go.

What do you think your timing is on the 8" batch box cores?  Asking for a friend.....

Hi Mike. Thanks for your interest (I mean... your friend's interest). I could probably have an 8" j style ready to ship out in two weeks, maybe three... I have the materials and plans, but I will need to figure out how to ship it since the boxes I bought for the 6" core are most likely too small. Cost would be $350 (shipping included) due to additional materials cost. Let me know if you are interested and I can send you additional specs. Are you using it for a RMH heater build? The risers are smaller on these than a brick riser, but from everything I've read that seems to be perfectly fine.

My, ummm, friend is thinking of a batch box.  So I'm thinking that's different from a J?

Hi Mike- whoops. I overlooked that part of your message. Please tell your 'friend' that unfortunately I'm not set up for an 8" batch box yet. I hope to at some point, but I don't want to get too ahead of myself.

Thanks,
Luke

No problem, thanks Luke!

Hi again! Just wanted to report that I now have an official website, and a video that shows the cores and how to assemble. Let me know if you have any questions or feedback. Thanks!

Rocketstovecores.com

Thinking about this ' Would surrounding the riser and back half of burn tube with chicken wire and cob would make it stable. Would the expansion properties cause the cob to break?
Like Walker, I like the finish of brick on the outside, possibly slate or tile on top of the burn chamber. Cob on the inside could be shaped to hold a barrel and direct the exhaust to the bench and chimney.

Hi Hans- what is the goal? If the core is left as a stand alone cooker or water heater a layer of cob around the heat riser should work fine as the cob won't be heating up as much. If a barrel is placed on top then a lot more heat is going to be directed down. In that case I would use something like pipe strap to hold the riser together. A piece of chicken wire wrapped around the riser and twisted together could work as well... I don't think the heat at that point would be too extreme though I can't say for sure. Basically, I there shouldn't be a need for any cob if there is a barrel on top. If the core is stand alone as a cooker then an outer skin of cob could act as a protective coating. You would probably have to build up the cob in stages so that it didn't slump off.

Does that make sense?

Cob or brick/slate down below around the burn tunnel makes sense in either case and can also be used to form way to hold the barrel/direct exhaust gases. The only drawback with cobbing in the barrel is that the barrel can't be as easily removed for cleaning/inspection.

I just assembled and fired up a ceramic fiber core I ordered from Luke so I thought I've give this thread a bump. Thanks Luke!

That's Awesome Aron!
Luke sells a fine product!     Easily assembled & a great price!
Your going to love it!

Probably should not burn it very long on your wood deck though... haha just ribbing you!

I love the idea of this. Especially if it could be delivered to my door! Bringing 50-100 firebricks which cost anywhere from 6$-12$  per brick, depending on thickness, on my ferry means quite alot of lugging and moving. The other option for me is putting it on a barge on a pallet. Which is about 60 dollars.

So this could be a time saver as well as money saver in some ways.


My question is what is the max length of wood which can be put in the 6" riser? As I see the wood feed is 10" high. I am wanting more like 16". Would putting 16" wood in the feed create smoke coming out the feed?

Or could this be modified slightly on my end, maybe with a ceramic fibre cloth adding about 16" on top of the riser?

Jordan - I think this is an swesome solution that is made more awesome in your situation.

And ... no.  Don't mess with the ratios and the length.  These things are keyed to the size of the core (burn channel cross section area) and adding or subtracting will move you away from an ideal.

If you want to put longer sticks into the J ... I'd suggest a metal frame that sits on top to keep those tall sticks from falling out!  An open metal frame won't significantly alter the breathing of the rocket - I'm just thinking of four 1/8" rods with a horizontal rod wrapping around every 2" or so.  I've heard stories of Ianto Evans of Cob Village just dropping a 6' cedar log in and walking away - without a supporting frame.

Also the longer sticks aren't going to cause smoke ... the fire should still occur entirely in the box, the sticks will slowly fall down as they burn.  The longer sticks will give you a longer period between feedings, but they also require checking to make sure they are indeed feeding in so its a bit of a wash in my limited experience.

Hi Jordan;
Yes , this shippable core is a sweet deal to get a start on an RMH.
In regards to your question.
Yes a 6" J tube should have a 16" feed tube as a standard.
Lukes cores are... well core only. You still need to surround the core in red clay bricks (or cob) the feed tube is standard at 16" on 6" and 8" J tubes.
So order one up today! Your wood will fit fine!  
And don't forget that        https://dragontechrmh.com/      sells all the other goodies you will need or want for your new RMH!