# Rocket mass heater



## tinknal

I'm thinking of building a rocket mass heater. I've been thinking of what I could incorporate into the system. I'm thinking I could add an oven, and maybe even a smoker. I was also thinking of putting in tubing so I could add a water heater. I have an old silo I plan to tear down and was thinking of using the concrete staves in the heater. Any ideas?


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## Ray

I looked at some searches a couple years ago and there are dozens of links with great ideas, and plans, you can do many things with them. big hearth to hold heat on one end. with everything in between, if you have room. do an image search on some of the search engines, best wishes, ray


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## glazed

I love the concept of the rocket stove, and all of its potential uses.

I'm obviously not very mechanical, and have to rely upon visual examples to help me imagine a project fully ... and so I just looked up what "concrete staves" are.

Since what you are wanting to do may be "a first" would you mind sharing more of what you have in mind? I am intrigued! Are you thinking of using the staves as your mass instead of plaster or stucco? 

I have done quite a bit of research on it, too, and have compiled lots of pics and videos to store in my dream file.

Here are some fave rocket stove pics, and also a snapshot of my tiny 16 rocket stove that I built on my recent two-week camping trip.


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## gobug

I like your photos, but do not understand your "tiny 16 rocket stove". In the last photo, I see 16 firebrick in 4 stacks of 4. Is that your tiny 16 rocket stove? Were the sample photos of other stoves made by adding cement to a framework like that illustrated in the first photo? The large stoves do not show the hot air path. Did they use a fire clay or fire mortar?


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## glazed

gobug said:


> I like your photos, but do not understand your "tiny 16 rocket stove". In the last photo, I see 16 firebrick in 4 stacks of 4. Is that your tiny 16 rocket stove?


Oops, I left out the word _brick_.

I was following the idea of this larger rocket stove ... for cooking ... it is smokeless.











Here is the video I used for my inspiration:

[YOUTUBE]XSMR2ANIZ7E[/YOUTUBE]




gobug said:


> Were the sample photos of other stoves made by adding cement to a framework like that illustrated in the first photo? The large stoves do not show the hot air path. Did they use a fire clay or fire mortar?


The sample photos (beneath the first one) were using earthen plaster and stucco to absorb and radiate the heat ... the hot air path is under the "benches."

The second photo is a little different ... the hot air is collected in the plastered drum immediately above the fire chamber, and the heat is absorbed and radiated out the mass. 

I don't know if I answered your question ... I hope I kinda did.


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## Nevada

Mama Crow said:


>


I guess what's throwing me with the above image is that the rocket stove is downdraft, while the 16 brick model is updraft. So how do you start the downdraft? It seems that the smoke and heat would want to go out the front of the stove, at least until you can establish a chimney effect.


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## tinknal

Nevada, this is what I'm trying to get my head wrapped around. Apparently several factors affect the updraft, including temperature differential between the inside and outside, and the insulating capability of the heat riser. I think the draw is created by some kind of vortex effect in the heat riser area. The efficiency is in part created by the fact that the system creates some kind of secondary burn in the flue gasses and this occurs in the heat riser portion of the system.


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## tinknal

Mama Crow, I was thinking of using the staves as a base, and maybe the flue. I would still use cob or concrete, but the staves would fill a lot of space and serve as building blocks for the system and add a lot of mass for very little effort.


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## Nevada

tinknal said:


> I think the draw is created by some kind of vortex effect in the heat riser area.


I doubt that. More likely it's the stack effect, where an updraft is maintained by hotter, and therefore lighter gases. But you have to get hot air into the stack for that to happen.

The place where you feed wood fuel into the stove is marked in the drawing as having a "grid", so I would think that heat and combustion gases would escape there (into the room) first.


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## tinknal

Nevada, the picture that you used omits a key portion of the system. There should be a structure that carries the flue gas downwards from the riser before it enters the mass and exhaust. There is a lot of videos on youtube for both rocket stoves, and rocket mass heaters. Paul Wheaton's Permies.com also discusses this extensively.


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## tinknal

From what I have gleaned there usually is a little smoke back until the system warms up.


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## tinknal

Nevada, if you could see inside of MCs 3rd, 4th, and 5th pictures you would see that inside of the barrels there is a heat riser that caries the smoke upwards and then back down.


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## glazed

I love your idea Tink! When you do it please post pics!



And as far as how it works or why it works ... or all the technical talk about it ... I have no clue, and that's over my head.

I'm afraid I can't participate in the serious discussion, but I will read along with fascination, and provide colorful commentaries (and/or photos) as I deem appropriate.

Which, may or may not be appropriate actually ... but, oh well.


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## wy_white_wolf

Nevada said:


> I guess what's throwing me with the above image is that the rocket stove is downdraft, while the 16 brick model is updraft. So how do you start the downdraft? It seems that the smoke and heat would want to go out the front of the stove, at least until you can establish a chimney effect.


I'd have to say whoever drew the graphics was mistaken. 

I wonder how it could have the "highest heat" at some other place than where the fuel burns.


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## tinknal

wy_white_wolf said:


> I wonder how it could have the "highest heat" at some other place than where the fuel burns.


I believe that this has something to do with the burning of the flue gasses. Smoke has a lot of flammable gasses in it that usually do not burn do to temperature needs. These gasses burn in the heat chamber. That is what makes a mass system 90% efficient. MCs photos actually show 2 different types of stoves. The simpler ones are rocket stoves and the second is rocket mass heaters. The rocket stoves can be made either updraft or down draft. I believe that the simple updraft models are called "pocket rockets". The most efficient ones have a pot skirt that carries the heat up along the side of the pot. Go on youtube and look around, there are all kind of systems featured there.


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## tinknal

Nevada said:


> I guess what's throwing me with the above image is that the rocket stove is downdraft, while the 16 brick model is updraft. So how do you start the downdraft? It seems that the smoke and heat would want to go out the front of the stove, at least until you can establish a chimney effect.


This image actually looks kind of like a hybrid between a rocket mass heater, and a European masonry stove.


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## tinknal

Let me add a disclaimer; I am a neophyte when it comes to this topic. Any info that I provide is iffy at best, and at worst down right dangerous. I am trying to understand this myself. Most of the questions and theories I am posting I am also posting on the permies site, where there are some folks who are experts on this subject. Anyone seriously wanting to understand these systems should go there too.


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