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Introduction to rocket ovens and what to know before you build

 
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Image Credits: All rocket oven images are provided by permies and used with permission

Rocket Ovens Are Awesome

This week my blog post - Rocket Oven – is it Right for You? Here’s What You Need to Know - focusing on a topic that is a bit new for me but one that I'm very excited about. Being involved with permies for over 2 years now and an active reader of permies threads long before that I have heard a lot about rocket mass heaters and other "rocket stuff." It all sounded cool and I figured one day I might try building one but since I was renting at that time it seemed a long ways away.

Even now that I have my 3 acre homestead building a rocket mass heater still seems like a lot to take on. That is where a rocket oven comes in - rocket ovens are much easier to build and are a nice way to get started with these rocket tech - rocket mass heater, rocket stoves, rocket ovens, etc.

In 2018 Paul launched his Rocket Oven kickstarter to fund the creation of a Rocket Oven DVD. This DVD is out now and I have been watching it and learning a lot about rocket ovens - I have been reading a ton on rocket ovens and I'm excited to build my own.

But the more I learned I also felt that most people were likely still trying to figure out this whole rocket business - basically where I was a few years ago. So to help those of you who may not be sure if a rocket oven is right for you or what it even is my blog post this week covers the following info on rocket ovens.

Blog Post Sections

- What is a Rocket Oven?
    - The Engine of a Rocket Oven: The J-Tube
    - The Oven Part of a Rocket Oven - White or Black Oven
- What are the Benefits and Costs of a Rocket Oven?
    - Benefits of a Rocket Oven
    - Costs of a Rocket Oven
    - Summary of the Benefits and Costs of a Rocket Oven
- Get Started with Rocket Ovens

If you're new to rocket ovens reading through these sections will give you a good overview of rocket ovens, and if one is right for you. This week instead of my normal cheat-sheet I made a little pdf based quiz you can get when signing up for my email list that will help you decide if a rocket oven is right for you.

In this thread I'm going to dive into the benefits of a rocket oven as I see them but I would love to hear from all of you about your thoughts on rocket ovens. Leave a comment and don't forget to check out my blog post. If you are one of the first to leave a comment on here you might even get a surprise in the form of pie or apples

Why Rocket Ovens Are Awesome



Rocket ovens have a number of benefits over traditional ovens but there are some costs too. No tech is perfect and that includes rocket ovens. My blog post provides a nice summary of the benefits and costs but here are the benefits as I see them.

Benefits of Rocket Ovens

- Cook food using twigs and small wood from your backyard.
- Very environmentally friendly compared to other types of ovens.
- Does not rely on the grid - great for the self-sufficient homesteader.
- Low and potentially neutral carbon footprint.
- Little to no smoke.
- Cheap to build.

What I'm personally the most excited about is being able to cook food using just twigs and small wood that I can collect off my property. If I combine it with a nice coppice grove I essentially will never run out of wood for cooking food while also being very environmentally friendly.  

Throw a rocket stove into the mix and I have a great off the grid cooking setup!

I also really like the low to no smoke side of rocket ovens. I'm tired of getting my BBQ up and running using a chimney starter and getting chased away by the smoke. I have noticed the same thing with cob ovens too. I want to cook outdoors on nice days but I don't want to deal with the smoke!

So a rocket oven sounds really great to me.

What About You?


Image Credit: Shared by Julia on her thread about building a beautiful rocket oven.

What about you? What do you think about rocket ovens and are you interested in building one?

Please leave a comment in this thread and don't forget to check out my blog post mentioned in this thread. If you are one of the first to leave a comment on here you might even get a surprise in the form of pie or apples

Thank you!

Additional Resources

- Rocket Oven DVD: If you are ready to get started with your own rocket oven I recommend checking out Paul's great DVD that goes step by step through the building of a rocket oven. I also made an "Unofficial Companion Guide" that I'm offering to those that buy Paul's DVD through my site that provides additional information to help you through some of the challenging or unclear steps. The guide will also be available on the permies digital market place as a standalone product if you already have the DVD.

- My quest to make a beautiful rocket oven: Julia's great thread documenting her journey to make a beautiful rocket oven.

- Would you replace your oven with a rocket oven? One of several threads that I made to help promote Paul's kickstarter - got a great conversation going about if people would replace their traditional oven with a rocket oven.

- What makes you excited about rocket ovens? Another kickstarter related thread asking what makes you excited about rocket ovens. I have shared a bit of why I'm excited but what about you?

- What would you cook first in a rocket oven? Just a fun thread from the kickstarter time asking people what they would cook first in their rocket oven.

- Solar ovens, haybox cooker - What would you build to go with a rocket oven? Rocket ovens are just one example appropriate technologies - solar ovens, and haybox cookers are others. This thread is also from the kickstarter time and shares some of the other cool stuff that you can build.

- Do you prefer white or black rocket ovens? Last thread from the kickstarter time - Just a simple question asking people if they prefer white or black rocket ovens. White ovens are where the fumes do not mix with the food and black ovens are where the fumes do mix with the food. Which do you prefer?
 
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This is my current favourite topic in fact I was the permie that suggested they create the rocket ovens forum within the energy forum.

I have my rocket oven mostly completed except for the engine and beginning testing which barring any other interruptions will start next week.   I have made a few design mods.  I hesitate to call them improvements until they are tested, but as most of them are improved oven insulation, I can't see that they will not be a help.

You mentioned a rocket stove with a rocket oven.  I have added a 3/16" steel plate inside the oven at they level of the door when open.  It can be used as a griddle to fry pancakes, eggs, or whatever if all but the top shelf is out of the oven.  The top shelf could be used to make toast. I will post sooner photos in the next post.
 
Ralph Kettell
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My stove, not quite ready for prime time, but mostly completed except for the rock wool insulation and outer shell.

The second photo is with the door open showing the 3/16" steel plate griddle.  Rocket Oven 1.1.

The first substantive mod 2.0 is insulating the area below the door.  The third photo shows this in progress and the fourth photo with it complete, and the fifth photo showing that the height is adjusted to provide a door rest that holds the door at 90° when open.  This of course means that my rocket oven is a 3 barrel oven to provide the cover under the door, but.......

The next part of mod 2 is using the piece of the cover that was cut out to make the lower door cover and using it to direct the hot air thru the oven to wash the back of the oven with the hot air.  The plate is mounted about 2-1/2" behind the rear wall of the oven. When it gets near the bottom it will obviously migrate to the top of the rear area before three cooler air which has been displaced to the bottom  goes out the exhaust.  This is shown in the final photo as R.O. 2.1.

That stage of the oven was done on Nov.10, more to follow.
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Rocket oven 1.0
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R.O.1.1 - Griddle Plate
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R.O. 2.0 - Improve Insulation
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R.O. 2.0 - Improve Insulation ModDone
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R.O. 2.0 - Door stop at 90 degrees
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R.O. 2.1 - exhaust redirect
 
Daron Williams
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Looks great Ralph! Your modifications are interesting and I hope you will post your results once it is completed. Thanks for sharing the pictures of your build!

You mentioned this is your favorite topic - what makes it so interesting to you?
 
Ralph Kettell
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More photos and more engineering changes.

R.O. 3.0

I didn't like the way any of the prior ovens were mounted.  It seemed like a real well..... oversight.  The oven is wrapped in rock wool, covered with metal and dropped into a sled of sorts.  Fortunately rock wool doors not compress horribly, but if you look at the photos off all the existing rocket ovens you can see the housing is compressed by the weight of the oven.  It is a quick and ready solution and it takes care is insulating the oven without a sneak path created by a mounting structure.    

I opted for a more rigid mounting structure with a minimal heat sneak path.  This is shown in the first photo R.O. 3.0.  Basically pop riveted some short pieces of angle and constructed two mounting brackets which will mount to the frame.  There will be rock wool insulation around the oven but inside the mounting brackets and the metal cover will attach to them also.  Then the whole oven assembly will bolt in place.  This part is done, but I do not have photos to show it off yet.   We drilled plus in angle brackets on the oven stand and welded nuts onto it so that it is easily removable to take the rocket engine in and out if necessary with minimal effort and no cob involved.

I am running out of battery so this will be short and sweet.  I am creating a bracket to over engineer the interface to the rocket engine.  The photos give a good idea of what is going on.  This was in process before the holidays and it had been on an extended delay.  It will all come together for initial testing in a couple weeks.

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Rocket oven 3.0 with brackets and string to lay out the Herat entry port
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R.O. 3.1 - Rocket Engine / oven interface
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R.O. 3.1 Engine Interface Front View
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R.O. 3.1 Engine Interface Side View
 
Ralph Kettell
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Daron Williams wrote:Looks great Ralph! Your modifications are interesting and I hope you will post your results once it is completed. Thanks for sharing the pictures of your build!

You mentioned this is your favorite topic - what makes it so interesting to you?



It is my first actual rocket stove type product that I will have built, but will not be the last.  I am an electrical engineer, rocket scientist so-called, but this is my first foray into more of a mechanical engineering type of project.  I always enjoy doing something where I can apply my skill set to a new problem.  This is a whole new class of problems.
 
Daron Williams
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Very interesting modifications - I'm looking forward to seeing it all completed! Thanks for sharing!
 
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Ralph - have you thought about cutting into the inner drum so as to direct the full force of the heat riser at the griddle plate? Maybe there's a 4.0 in the offing, with a sliding panel that converts it from normal oven to superheated griddle operation.
 
Daron Williams
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I think brainstorming some new ideas is great - might not be right for Ralph's oven at this point but perhaps someone else will come along and try it out! Always good to share ideas and brainstorm as a community.

So Phil - what do you like about rocket ovens?
 
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I suspect this variant should really be called a rocket barrel oven rather than a rocket oven.  There are lots of people who have ovens as part of their rocket stoves.  And there are barrel ovens that are not heated by rockets.

A rocket barrel oven looks interesting but for some the amount of work needed to build them looks scary
 
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Graham Chiu wrote:I suspect this variant should really be called a rocket barrel oven rather than a rocket oven.  There are lots of people who have ovens as part of their rocket stoves.  And there are barrel ovens that are not heated by rockets.

A rocket barrel oven looks interesting but for some the amount of work needed to build them looks scary



Ya - that would be potentially more accurate but rocket oven works too

I hear ya on the work needed to build them. I don't have a lot of experience working with metal but I was impressed by the rocket oven dvd for helping to explain and show all the steps and there are some good plans for the j-tube part. The j-tube really seems fairly simple to build as long as you get the dimensions and materials correct. I still need to build my own and it will be a bit of a challenge but a fun one and I'm excited to add it to my future outdoor kitchen!
 
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Gorgeous work, Ralph. Please keep us updated.
 
Ralph Kettell
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Great idea Phil and thank you Matt.  More photos to follow when I have time to finish it.  I will move them to a separate post so that this can go back to what Daron originally intended.
 
Ralph Kettell
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Graham Chiu wrote:I suspect this variant should really be called a rocket barrel oven rather than a rocket oven.  There are lots of people who have ovens as part of their rocket stoves.  And there are barrel ovens that are not heated by rockets.

A rocket barrel oven looks interesting but for some the amount of work needed to build them looks scary



It is not an insignificant amount of work for sure but it is fun.  I am an experienced woodworker, but prior to this had never worked with metal fabrication, except for very limited sheet metal work.  Any time I am learning something new it is fun.  My only complaint is that working with steel is the DIRTIEST job imaginable.  I am beginning to use gloves. It is dirtier than working on cars, not much but still dirtier.
 
Graham Chiu
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Hi Daron, just wondering what progress you're making with your barrel oven.

Also does this design not require a pizza stone to crisp the base?
 
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