It's been a full summer. Lots of projects going on around here! Among them, my natural building apprentices spent a LOT of time experimenting with rocket stoves for cooking. Over the course of the last couple of months, we've built an outdoor cooking complex.
First, we fixed up a small but traditional wood fired, beehive oven. Then, after using that for a time, we built a double ended stove (2 rocket stoves) for boiling/frying.
This is early on in it's development. 2 rocket stoves, the one on the left began as an Aprovecho-style, horizontal feed; the one on the right, a J-tube rocket. Later, the horizontal feed was modified into a J-tube as well.
Here is roughly how the internal channels go.. Notice that there's no chimney here, you can cook/heat food on ANY port up on top. For exhaust to flow out, one of the ports has to remain open; we often placed a chimney over one of the cook-top plates and cooked on everything else (simultaneously).
This middle(ish) cook-port got remade into a deep pot heater with a combination chimney, chopped into the side (and a tea-cup warmer added).
Yep.. We ARE using coffee cans as a chimney. Works just fine, so far! Oh, and yes.. Both stoves vent through the one chimney.
notice how the pots sit deep into each "pot well", this maximises heat getting into the pots. Other cook surfaces can be used as well.
After much experimentation, a few changes and some decorations later, this stove is functional and beautiful.
Besides the coffee cans, is the entire build cob? I see what looks like firebrick in the pictures.
What you see are adobes, which are basically cob popped out of a brick form and allowed to dry before use. I LOVE using adobes, they take time to prepare but REALLY speed things along on build-day!
The whole thing is made out of cob/adobe. The fire(s) are insulated with perlite/clay, which is the only bagged/ready-made product in the works. We are using a couple of old fire-bricks on the feed openings to meter the air..
After building the pot cooker, the next logical step in our experimentation time was to try to build a rocket powered baking oven.. So..
First, the stand with rocket core. We had to tilt the heat riser to get it centered in the oven base.
We made a couple of different options for heat path. One option is straight through the center, this can be plugged which will send heat through eight little channels that pass under the baking floor. These channels were built by cobbing over a tomato paste can and carefully slipping it out while working.
Then we temporarily plugged the holes and built the oven on top.
It worked great and produced excess heat, so it was decided to add a double-boiler hot water system.. Notice that the exhaust to the water heater comes from the bottom of the oven and drops down quite a bit before going 'round the water pot.
The double boiler system.. An open pot (of water) is heated directly and has a copper coil in which is pressurized. The pressurized coil has a higher boiling temperature than the open pot and will NEVER be dangerous. It also has the curious ability to provide MORE hot water than the volume of the pot being heated (at a reduced temperature certainly, but still quite hot).. Pretty neat trick!
Then of course, our very artistic apprentices decorated.
Very beautiful! And, then there was PIZZA!
The digital thermometer in this image shows 388 F. Just to point out that the oven can get up in the 600 F range for cooking pizza.
Ronyon, I made a metal door, is it not in the images somewhere? Without the door in place, the water heater gets no heat..
Interestingly, this oven works in reverse to the traditional wood fired, pizza ovens.. Here, the heat builds AS you cook, with foods that cook at cooler temperatures going in first and higher temperature cooking happening later.. Normally, it's the other way around.
The oven has a layer of perlite/clay as insulation.
There is NOT a protective coat on these.. I need to build a roof before it rains.
How long does it take for the plain cob rocket oven, without a boiler, to reach temp?
The boiler has ZERO effect on how hot the oven gets.. The boiler gets its heat AFTER it's run through the oven, a reuse of the oven's waste.
Depends on what you want to cook.. Granola wants a low temp and you can start cooking it pretty much right away.. Pizza needs high temps, which takes an hour or more of firing. A very nice feature of this stove is that you can keep on firing it as you cook..
Thanks for the responses Donkey!My wife is totally loving these cookers, and she wanted to know if you used a trench around the structures or a stone foundation, to avoid ground water wicking issues. Both of us are amazed and preserving the coolness is on our minds.
With all my posts, please keep in mind I have one cheek still firmly in the armchair...
No trench.. Just urbanite (broken sidewalk) on the ground as a moisture-break and cob on that. It seems prudent to build a higher foundation than we did. I expect some water damage down low from splash. These cookers were not originally meant to be permanent, they started out life as experimental "kick-overs". Things kinda got out of hand and now, i've got to figure out how to protect them.. They're too nice to just let go to hell..
TexasGonzo: Sooooo glad I found this site! Its always rewarding to find such a super group of folks! To any and all, feel free to PM me anytime. Thanks for having me!
Mar 11, 2019 18:56:41 GMT -8
jlmtech: GADGET: CONSIDER USING A JET PUMP INSTEAD OF A BLOWER FAN TO INDUCE DRAFT; NO CLOGGING.
Mar 26, 2019 8:19:28 GMT -8
michaelegan: i am unable to open the sketchup files on my mac. I used sketchup a few years back but apparently the company now requires a subscription. does anyone have any advice/instructions on how to use the program or how to view pictures without spending money?
Aug 20, 2019 18:41:48 GMT -8
mannytheseacow: michaelegan: download AutoCAD student version for free... import .SKP
Aug 23, 2019 13:33:44 GMT -8
topbaza: hi everyone, been searching all over net and this is were i need to be i think!!
Sept 28, 2019 6:16:25 GMT -8
anounaki: Hi, why I cant upload photos when I make new tread to this forum?
Feb 28, 2020 2:09:40 GMT -8
ahansen: photos under 1 mb not possible?
Jun 4, 2020 0:09:21 GMT -8
belgiangulch: Photo's are possible. They must be downloaded elsewhere and the image url (adress) is copyied.
Sept 14, 2020 7:26:15 GMT -8
belgiangulch: While creating a thread click on the small picture in the banner above the reply. A box pops up, paste the image url in the box. Pay no attention to the huge list of numbers and such.When you finish and hit reply your post with pictures will come up.
Sept 14, 2020 7:29:27 GMT -8
deadstarsstillburn: Hi there. I was directed this way by folks on the Permies.com website and am hoping I can get some information on how a total newbie can get started designing, siting, building, and not-dying-in-a-horrible-house-fire with a new RMH in a 160-year old home
Oct 21, 2020 6:52:10 GMT -8
deadstarsstillburn: The people over there recommended either a 6" batchbox or an 8" J-tube. I don't know what those are but am going to try to figure that out. What I need is a blueprint that I can scale to fit the need for my house. I have something likne 5000 square feet
Oct 21, 2020 6:53:00 GMT -8
deadstarsstillburn: but I do not need to heat all of it by any means. probably only need to heat half of that, maybe less.
Oct 21, 2020 6:53:15 GMT -8
deadstarsstillburn: moreover, the house has 3 storeys (large attic) so I assume if I get very efficient heating on the ground floor, that will go a long way toward heating the upstairs as well, no?
Oct 21, 2020 6:53:59 GMT -8
BenAlexanderT: Happy new year everybody. I wish you the best
Dec 31, 2020 15:06:14 GMT -8
Solomon: Anybody in Southern Oregon, in Jackson or Josephine counties?
Jan 16, 2021 21:54:43 GMT -8
gnomedome: i realsie this is from 2009
Apr 14, 2021 8:30:44 GMT -8
gnomedome: i realize this is from 2009 id love to see the photos from this ..as im looking to build a sauna soon similar to this .... if anyody sees this post email@example.com..... the photos in this post did not show up
Apr 14, 2021 8:32:00 GMT -8
dcoyte: I am planning to use a cast iron heat exchanger out of a hydronic boiler set on top of my rocket stove, flue out the top. There will be a pump moving the water through the heat exchanger into an unpressurized 2000 gal tank. Any thoughts?
Dec 31, 2021 6:45:55 GMT -8