Rocket stove with bread oven

[strawhouses]

Are there plans available (Ianto's Rocket Stove book?) for building a rocket stove with a bread oven above it? I would like a cooking surface for boiling water, etc. but also have an oven for making pizza etc.

Or will the oven slow the airflow too much?

Thanks.

[Donkey]

I haven't seen any plans as such.. Though a couple ways to do it occurs to me right off the top.
One would be very much like the bell rocket that peterberg has been experimenting with. I would build the oven or bell out of cob, with the rocket below venting directly into the bottom, exiting again out the bottom. This setup could be simple to build, the bell arrangement would distribute heat quite evenly and it could be a great setup for continuous firing. The disadvantage being that when you open the door, any burn products present would flow into the room.
Another way to go about it would be to make a metal box (or even a cob dome) and build channels around it for the heat to flow by, heating the box from the outside. The advantages of this system being able to run a continuous fire, extending baking time, and when the door is opened, no burn products could enter the room. The disadvantages being more complicated to build and I imagine it would create hot/cool spots in the oven and an uneven baking heat.

Neither of these methods afford an obvious or convenient place to make tea..
I kinda lean towards the idea of making two (or more) smaller rockets for cooking. One to heat the oven and one to set a pot on. I know it can complicate the design of the chimney(s) somewhat but I like putting the fire where it's most effective. It seems to me that a good cooking fire should concentrate the heat where it's needed and splitting functions up (oven/cook surface) can over complicate a process that may create a gizmo unsuited to either task.

Just one guys opinion... It's certainly possible that I'm wrong here and I remain open to other thought forms.
If someone comes up with something that works -- well, please share it here, on these boards.

[chronictom]

"I know it can complicate the design of the chimney(s)"

Could you just have them both go into the exhaust pipe with dampers in them so you could turn either one off, only opening it when that stove is going?

As for uneven spots, I think that would only be an issue if you used too thin of a cob 'wall' for the oven. I think (no clue if it's right though), that if there was at least 4 inches of cob, it would tend to all heat up pretty evenly on the inside. Alternatively, lining it (cross ways to the heat vents around the oven) with strips of metal (maybe just rebar?) would help spread the heat more evenly... although there could be an issue with it and the cob reacting differently to the heat?

Tom

p.s. This is my first post here... I was just re-introduced to the concept of rocket stoves and after seeing some of the examples that have been done, have been completed sucked into them... lol Some of you are doing amazing things...

[Donkey]

The shared chimney, multi damper thing can work.. Also, one could do the chimney calcs and skip the dampers.
However, dampers can be forgotten and calcs can be wrong...

Well, with a constant fire there are just gonna be hotter places than others.. It's the nature of things.
I imagine the one will tend towards a more even heat distribution than the other.. Just a guess without any testing on the matter. It could very well be a negligible problem or an easy fix either way..
A little "soak" with the fire off will even things out in any case.

[jpmanley]

This is not what you asked for, but I thought I would throw it out anyway.
Generally speaking, the more variety of applications that we try to make ovens/fireplaces/rocket perform, the more complex the structure becomes, and most often the less effectively each application will perform solo.
I would build an earth oven to make pizza or bread in, and alongside of it build in a simple earth faced rocket that has a plancha above it with removeable plates. The additional cost is not much.

Serious hot oven to bake with, and a small low tech fire to boil water, etc. Each will do what it does best.

For what it is worth, I have been building bakeovens and masonry heaters for a living for over 30 years. I have tried all sorts of combinations, and I tend to keep it simple and stick to the basics (in construction anyway).

Just my 2 cents.

Pat

Aug 8, 2008 23:16:21 GMT -8 strawhouses said:

Are there plans available (Ianto's Rocket Stove book?) for building a rocket stove with a bread oven above it? I would like a cooking surface for boiling water, etc. but also have an oven for making pizza etc.

Or will the oven slow the airflow too much?

Thanks.

[peterhoole]

Having, last year, built a conventional masonry bread oven for fun I have also cooked pizzas in it. However it is quite big and takes several hours to heat up. I then came to rocket stoves and it crosses my mind that a masonry bread oven could be heated up faster and more efficiently with a rocket stove at the back end discharging directly into the oven. It then occurs to me that a much smaller oven with a lower mass/wall thickness could be built in the same way specifically as a domestic pizza oven, clean, quicker and with a continuous heat source as pizzas require, it would probably make a brilliant BBQ as well. I need to build one to see if it works, it might not gain sufficient temperature in the hearth. Does anyone have any thoughts or experience?

[Teach]

I have seen pics detailing the construction on the web that appeared to be a weekend project for freinds and neighbors. The layout had the rocket with horizontal feed at one end, the oven in the middle and the stove pipe and cleanout at the other end. Heat rises up from the rocket and travels under the metal plate that sits on top. In a normal type cook stove the gasses would continue under that plate to the opposite end and then exit up the chimney. This set up had a damper that controlled the amount of heat to the oven by controlling how much of the gasses went down one side of the oven....underneath the oven....then up the opposite side of the oven as well as across the top. With the damper wide open it only allowed gasses over the top of the oven and underneath the steel top. I believe the workshop was in San Diego CA. That might help to find it using a youtube search.

[apalmer]

I am setting up a home-based bakery and have been attempting to design a bread-baking oven using some of the concepts discussed in this thread. My current thought is to have the oven heated indirectly and have two fully separate compartments. A damper system would allow me to start the oven with a straight path up to the chimney or to route the flue gasses around the lower or the upper oven. Because I'm trying to produce commercial quantities of bread, I have the compartments sized at about 36" x 52". A few concerns at the moment:
1) My calculations of the mass show that this will be impossible to heat. Hopefully I have made an error, but if not, this thing needs to be scaled down to a single oven and I need to remove a bunch of mass from the exterior and just keep it solely around the baking compartment.
2) This will be fairly complicated/expensive to build, but it would be worth it to me if it bakes well and efficiently. I do have plans for multiple types of baked goods and having had experience with a Denzer-type oven previously know that I could make good use of oven temperatures that coast down - breads, muffins, granola, etc.

See my calculations and Google Sketchup at www.boxturtlebakery.com/Home/ovenplans

Comments and suggestions welcome,
--Abraham

[Donkey]

Hello apalmer..
Welcome to the board!

I'm not sure that I completely understand what it is you have in mind based on your drawings.. Your project sounds interesting though..
Perhaps if you could show a little more detail, or perhaps describe the layout..

One thing though, right off the top.. It looks complicated.
It might be best to simplify, especially if this is your first rocket stove (or oven or what have you). Make something simpler to start with. Once you have it well in hand, have used it, know the pit-falls, etc, you can take that experience and build something bigger and better.

[Donkey]

The design that attracts me is the one I mentioned before..
Beehive, cob oven with a rocket stove under it.

The simplest, least expensive way that I've imagined it is to build a rocket stove into the foundation..

Then build on top of that a cob beehive oven.

(image point of view is rotated to see the heat riser inside the stove)
The door would act as the vent, no chimney.. I imagine that if the proportions are right between the inside of the dome and the rocket stove pipe size, that it would act like a bell stove.. Heat distribution should be pretty good.
An improvement over this would be to include a chimney, which I would attach low somewhere. This would allow for the door to be closed while burning, perhaps improve draft, etc.

I've been wondering where the best place to bring in the heat might be.. I've thought the back, the middle, branch to multiples around the edges, etc, etc... Then, just the other day I watched a friend of mine cook in a professional Italian made jobby.. He tucked a small fire in just to the left of the door (after getting it all up to heat first) to keep things hot and the fire out of the way. So, I figured... What the heck, I'll stick it over there.

[lnmal]

Hi,
My first post!
I've read a lot of useful information in here before building my own Rocket cookstove/mass heater WITH bread oven last fall. Thanks to Donkey and you all, here is what we did:

The oven sits on top of the ashtray and shares the chimney with the rocket so... only one is fired at a time, but the oven is a plate-warmer while we cook dinner.
You'll find some pictures of the building process here since I can't seem to figure out how to post one directly into my message:
es-cargo.qc.ca/commun/rocket/index.html
LN

[canyon]

Inmal,
That is amazing! What a great job! I am so glad you shared! You did such a nice job photo documenting! Wow! I might need to repeat... Wow!

Have you been using this all winter? How has the outside combustion air feed worked? What are you really happy with on this? What would you do differently doing it again? How big of a place is this heating and what type of construction?

I hope you don't mind all the questions!

[lnmal]

Thanks canyon,
I'm glad you liked the photos. If you want to find out more about the house itself, just visit our website www.es-cargo.qc.ca where you'll find our blog and lots of pictures.

We live in an earthship type house, 800 sq. ft on two stepped back levels. We are passive solar with wood burning back-up heat. It was our 4th winter in the house but the first with our Rocket. We had an old Findlay wood burning cookstove before that... what a difference! In -20F weather, the heat stays inside the house where we need it, the bench is cozy warm for breakfast in the morning.

We're on solar panels for electricity and we use propane only for our on-demand water heater (and a small camping cookstove in summer). That's why our rocket was designed to handle all our cooking. The top of the barrel had to be low enough for me to put on and remove heavy pots safely. The top was replaced by a 3/16" steel plate with an extra donut shaped ring hoping to keep it from warping... it should have been an extra layer in the center instead, but it still works great.
My husband loves to sit by the feeder and stoke the fire to get the temperature just right for what I'm cooking. Last fall, I used it to do some canning because the propane burner started leaking in the middle of the process... the bench wasn't even dried yet, but the blackberry jam was saved!

As for the fresh air feeder, it works fine but we had to tweek it somewhat. There's an operable gate at the tube's entrance to stop the frigid air from invading the living space when the fire is out. We also added a small computer fan that we can turn on for a few minutes to help get the air moving. If smoke threatens to come indoors, we start the fan and put the cover on the metal feeder: you can hear the rocket lifting off!!!
Also, to restrict the flow at the end of a burn, we use a steel plate to partially block the top of the brick feeder.

I'm not sure what we'd do differently about the rocket but there are a couple of things about the bread oven, mostly as far as the door is concerned. It should have better anchoring into the cob... but that might cause more cracking? The second door we use for air intake and feeding the fire should be combined into the main door... but we didn't know how the whole thing would work before we started using it. Surprisingly, it burns quite clean ounce it gets going. After a couple of hours and an armful of wood, we close everything and let it die down. Another 30 minutes and it pizza time! We've cooked a 9 pound chicken and had enough remaining heat to bake bread and granola.

As you can see, I don't mind all the questions

LN

[johng]

LN -- thanks a lot for the link to your site. I really like your design, and would love to hear how things have been going with it since you got it finished.

A few questions: are you using it to cook during the summer? If so, do you have trouble overheating the house, since the stove is hooked up to the high mass bench?

Also, it appears that your bread oven vents more or less directly to the outgoing pipe -- do you find that the oven portion is able to soak up enough heat, or do you lose a lot (in other words, do you find that the exhaust temp is a lot higher when you use the oven than when you use the stove)?

Donkey -- thanks for the drawings for a rocket-fired bread oven. I'll be trying this out!

-john

[lnmal]

Oups! Sorry, I've hadn't looked at this post for a while I guess... hope you still want the answers.

Yes, we use it to cook all year, but we do have a small propane camping stove if we're in a hurry or for boiling water when there isn't enough electricity (we're off-grid)
We use fast burning wood in the summer, mostly very dry trembling aspen so the fire goes out quickly. The mass of the house is so huge, we don't feel the difference.

The chimney for the bread oven is connected to the main stack for the rocket. There's a sliding trap that blocks out the oven's chimney, just above the door. My husband made that and soldered it onto the door's frame. You can see it in the pictures at the bottom of this page: es-cargo.qc.ca/commun/rocket/index.html

The oven is not as efficient at storing the heat, but with an armful of hardwood in a 2 hours burn, I can bake 4 pizzas, one bread, a roast or chicken, cookies, granola + dry fruits and vegetables overnight, that's plenty for one evening.

Obviously, we can't use both the bread oven and the Rocket at the same time... and if the rocket gets smoky, it's usually because we forgot to close the trap on the oven.

LN