rocket/bell project

[grizbach]

"RMH's drive engine is NOT the stack effect in Riser alone.
It's the difference of the stack effects in Riser and Downer.
If you want more draft, you can get it by cooling Downer.
If you want exhaust heat reached deeper, you have to cool Downer
more effectively and/or cool it at higher position."


I feel this is the drive also. What else could it be???
I think Erica from the permies forum touched on this also.

[Donkey]

I understand you, and I think it's a very interesting idea.

I've often thought that it may have something to do with pressure created by the heated air volume trying to expand against the constriction of the walls.

I have accidentally wrecked the flow of a stove by creating an overlarge chamber directly under the heat riser. If the stove were driven entirely by stack effect, I imagine that the volume below the heat riser would not matter much.
Also in other circumstances, I've repaired flow by stepping down pipe sizes downstream in the storage mass. Smaller pipes run hotter, one would think that this would provide a negative influence on the stack balance.. Though to be fair, it could also provide warmer air to the chimney, improving stack effect there.

[ytksgmt]

Apr 6, 2010 16:40:15 GMT -8 Donkey said:

Are you willing to do this testing and post your results here?

You mean practical experiment ?
I WAS willing to experiment it.
My purpose is to bring exhaust gas 50 to 100cm beneath the level of combustion chamber and warm the ground of my house.
But, after calculation, I'm thinking I have to reconsider the design completely.
I know I should experiment it.
Experiment of checking that my design can't work...

Also, I think this should have it's own thread. With your permission I would like to move it.

Yes, please.

As for overlarge chamber, with my calculation, volume change causes the difference.

[Donkey]

Umm.. It will prove difficult to move these posts to a new thread cleanly.
So, I will start a new thread and copy your original post there.

IF you would be so kind as to attach your image (plus more) over at the new thread.

[annpesch]

Hi,
I am new to rocket bell stoves. I have been totally enthralled with masonry heaters, but I am finding the rocket bell to be a happy combination of masonry heater and the rocket stove....am I correct in this?

I have a few questions:
1. How do I open the plans that petersburg has so graciously posted? I know that I am not totally computer literate, but this is ridiculous!
2. Is there any way to incorporate an oven in the second bell of the heater?
3. I saw that there was some discussion on the possibility of running the heater to a second story....keep the mess downstairs (in our garage), and some of the heat upstairs....is this feasible? How much clearance do you need to have between the sides of the heater and the flooring, floor joists, etc.?
4. Is there any way to use this system as a smoker or dehydrator when not being used to heat your home?
5. Would this type of a heater be impossible for the normal do-it-yourselfer?

Thanks so much for any help and answers you can send my way!
Ann
JMJ

[Donkey]

Apr 11, 2010 22:43:08 GMT -8 annpesch said:

Hi,
I am new to rocket bell stoves. I have been totally enthralled with masonry heaters, but I am finding the rocket bell to be a happy combination of masonry heater and the rocket stove....am I correct in this?

Welcome.
Yes, I'd say that rocket bells ARE that happy combo.
Peter's done a fine job of marrying the two.

I have a few questions:
1. How do I open the plans that petersburg has so graciously posted? I know that I am not totally computer literate, but this is ridiculous!

You will need Google Sketchup, which is a free, 3D design program. Here is their link.

2. Is there any way to incorporate an oven in the second bell of the heater?

Yes.. Tentatively.
Though the second bell may be too cool for a good pizza.

3. I saw that there was some discussion on the possibility of running the heater to a second story....keep the mess downstairs (in our garage), and some of the heat upstairs....is this feasible? How much clearance do you need to have between the sides of the heater and the flooring, floor joists, etc.?

Most everything is possible. Only you can say what is practical for your use. Creativity is a beautiful thing.
I can see putting the rocket feed and all that downstairs and placing a bell or two (or three) upstairs.

To clearances, I'd say follow the fire code of your area. I think in most cases code requires somewhere between 12 - 18 inches.. ?? I think it depends on a lot of factors, triple walled, insulated stove pipe will need less clearance than single, non insulated.. Ask someone in your locality that knows the rules.

4. Is there any way to use this system as a smoker or dehydrator when not being used to heat your home?

Same as above, creativity and all that.. Why not?
One of the great things about rocket stoves is their versatility. Though, they don't typically smoke so that might cause ---- problems there, but as a food dryer, yes.

5. Would this type of a heater be impossible for the normal do-it-yourselfer?

Define your terms, what is "normal"?
Peter is a highly skilled individual with plenty of practice under his belt. His design and methods are advanced and shouldn't be taken lightly. I'd say it would be quite difficult for someone who's never laid brick before.
What is MOST important are the underlying principles that Peter has shown. His design (or ones like it) can be converted to other materials, other ways of building.

Thanks so much for any help and answers you can send my way!
Ann
JMJ

Soitanly.

[annpesch]

Thanks for the quick answers!

I do have a question about this response however:

"To clearances, I'd say follow the fire code of your area. I think in most cases code requires somewhere between 12 - 18 inches.. ?? I think it depends on a lot of factors, triple walled, insulated stove pipe will need less clearance than single, non insulated.. Ask someone in your locality that knows the rules."

I have an existing chimney that I would like to hook into (it is monstrous, and has several, separate flues), so the exhaust isn't what I was referring to. I was wondering how much clearance there needs to be between the sides of the heater(where the bells are located), and the floor...consisting of wood, joists, etc.

Have any of you built a rocket/bell (besides peterberg) and are using it on a regular basis? Are they happy with them? I read in a previous post that rocket bell heaters are the "poor man's masonry heater"....if that's the case, this is exactly what I need!!

What exactly is the difference between a regular double bell heater and a rocket/bell heater?

Also, do you have any suggestions on how to download peterburg's plans? I've downloaded Google Sketchup successfully (or so it tells me), saved the file from peterberg, and then when I try to open it, everything disappears on me! Does anyone have any idea what I am doing wrong? Is there any other way that I can get this information.

Thanks again for any help. It is greatly appreciated.
Ann
JMJ

[Donkey]

Apr 12, 2010 12:18:22 GMT -8 annpesch said:

Thanks for the quick answers!

I do have a question about this response however:

"To clearances, I'd say follow the fire code of your area. I think in most cases code requires somewhere between 12 - 18 inches.. ?? I think it depends on a lot of factors, triple walled, insulated stove pipe will need less clearance than single, non insulated.. Ask someone in your locality that knows the rules."

I have an existing chimney that I would like to hook into (it is monstrous, and has several, separate flues), so the exhaust isn't what I was referring to. I was wondering how much clearance there needs to be between the sides of the heater(where the bells are located), and the floor...consisting of wood, joists, etc.

Oh, sorry. The I.B.C. (international building code) says:
2112.5 Masonry heater clearance.
Combustible materials shall not be placed within 36 inches (765 mm) of the outside surface of a masonry heater in accordance with NFPA 211, Section 8-7 (clearances for solid fuel-burning appliances), and the required space betweent he heater and combustible material shall be fully vented to permit the free flow of air around all heater surfaces.

Exceptions:

1. When a masonry heater wall is at least 8 inches (203 mm) thick of solid masonry and the wall thickness of the heat exchange channels is at least 5 inches (127 mm) thick of solid masonry, combustible materials shall not be placed within 4 inches (102 mm) of the outside surface of a masonry heater. A clearance of at least 8 inches (203 mm) shall be provided between the gas-tight capping slab of the heater and a combustible ceiling.

2. Masonry heaters listed and labeled in accordance with UL 1482 and installed in accordance with the manufacturer's instructions.

Also, do you have any suggestions on how to download peterburg's plans? I've downloaded Google Sketchup successfully (or so it tells me), saved the file from peterberg, and then when I try to open it, everything disappears on me! Does anyone have any idea what I am doing wrong? Is there any other way that I can get this information.

After installing Sketchup, you should only need to double-click the file. Have you installed Sketchup?

[peterberg]

Unfortunately, google has messed up the links to the latest version of SketchUp. Everything is alright, until you try to download the program. And instead of version 7.1 you'll get version 6.whatsoever.

I do have found another link which will deliver the correct file.
This is the link: www.filehippo.com/download_google_sketchup/
I've tried it and it is the last version indeed.

One of your questions was: What exactly is the difference between a regular double bell heater and a rocket/bell heater?
The combustion chamber and afterburner is the difference. In fact, the rocket-ish syphon doesn't burn any wood, only the gases produced by the initial pyrolysis of the fuel.

And another question about the rocket/bell being the poor man's masonry heater.
The rocket/bell is not, because of the work and the materials involved.
The rocket mass heater Ianto Evans' style, definitely is.

[peterberg]

Some weeks ago I came to a conclusion, there ought to be other factors in play, but this is my explanation.
According to the law of Bernoulli the syphon do act as a venturi. Velocity, pressure and volume of the streaming gases should be summing up to the same amount. When one of the factors is going up, one of the others has to go down. So, the venturi acts as a velocity booster and the pressure goes down at the same time. That's why the steel pipes right in front of the syphon do work so well. The lower pressure sucks in fresh air.

Other factors:
The vertical part of the syphon do act as a stack, and the higher the temperature difference with the bell, the greater the velocity.

The flames are taking the shortest trajectory they can get, very close around the hanging separation inside the syphon. As a result, at the bottom the gases have to be going very, very fast. Even when I do make a small starting fire at the bottom there's nothing to be seen the next day. No ashes, no charcoal, nothing. All what was there is blown away. I'll have to add that I am using a feature which is called a "trip wire" at the sides leading to the bottom. The function is to disturb any laminar streaming.

These factors do contribute greatly to the vigorous and much needed turbulence which is taking place in there.

That is to say, that's what I do think.

[annpesch]

Either my brain isn't functioning correctly, or my computer isn't.....I still can't open the plans. Google Sketchup 7.1 is installed(I can draw things, etc.), the plans are supposedly saved in my documents, but when I click to open it....poof! everything goes. Any suggestions?

Remember, I am not very knowledgeable about either the rocket bell heater or masonry heaters, so keep this in mind when you see some of my questions....

Does the rocket bell heater "harvest" the heat as well as a masonry heater? Does it all depend on how much thermal mass you have?

How about the second bell.....I have read that this bell will naturally be cooler than the first bell. If I wanted an "oven" in the second bell, would it be as simple as putting a door in? (The ignorance is really showing now, isn't it?!) Would the second bell get hot enough for a slow cooking type of oven?

I see that there is some type of pipe in the photos of the heater....about how hot does it get in that chamber? Does the pipe hold up to the heat? Are the pipes hooked to outside air....if I understand correctly the pressure drops in the burning area and fresh air is pulled in through the pipes? Just trying to understand the whole concept.....

Once the gases burn (not really understanding that, but perhaps I don't need to) the hot air goes to the top of the first bell...as it cools, it goes up to the secondary bell where is goes through the entire process again. Am I getting this right? While in the bells, heat is absorbed into the thermal mass where it is gradually released into the room.

Am I getting close to understanding the basics? What advantage would there to building a typical masonry heater over a rocket bell heater? It appears to me that the rocket bell has an even more efficient initial burn, is that correct?

Thanks for all your patience!

Ann
JMJ

[annpesch]

Please disregard my previous post. I stayed up most of the night reading previous discussions, so I think I am understanding the concepts pretty well....

The only part of the post that I would like to know about is the ease of adding an oven....simple as putting a door in a second bell? I'm sure it really can't be as easy as that....

[Donkey]

Apr 14, 2010 7:46:11 GMT -8 annpesch said:

The only part of the post that I would like to know about is the ease of adding an oven....simple as putting a door in a second bell? I'm sure it really can't be as easy as that....

.. You could do that, though you would risk exposing yourself to harmful burn products every time you open the door.
Seems that sticking a metal box inside with a door in to that box (through the wall) would be better.
I think I didn't say that in the most clear way, but I think you understand..

[peterberg]

annpesch,

Donkey's right, running the stove and opening the oven door in a second bell seems to be dangerous. This is what heater masons would call a "black oven", in contrast with a "white oven", which is only heated from the outside. I.e. the smoke path is going around the oven compartment.

Utilizing a black oven, it can only be used when the fire is gone. Apart from the fact that the second bell might not get hot enough to bake anything. Cooking, on the other hand, seems to be quite possible.

Placing the first bell on top of the combustion chamber and locating the black or white oven in there will stand a better chance of success. The exit opening of the heat riser could be in or direct under the bottom of the oven, respectively. As an aside, you'll get a convenient level for the oven door as well.

The above possibilities are based on an oven made entirely out of ceramic material, of course. Brick, fire brick or refractory castable are my materials, less so for metal boxes etc.

[annpesch]

Thanks Donkey and Peter for your answers. So, if I am understanding this correctly, I could have a single bell with an oven on the top of the first bell? Would this oven actually be part of the first bell with nothing to separate the bell from the oven...(wouldn't this be considered a black oven), or would it work to have it a separate chamber....separated by a ceiling/floor of firebrick. Would there also have to be air circulating around the top and sides of the oven in order to heat it up sufficiently?

I have another question. Does a second bell "harvest"....for lack of a better word....the heat much better than a single bell, or is there not all that much difference between the heat thrown from a single rocket bell system, and the heat thrown from a double rocket bell?

I'm kind of slow at picking this stuff up; you'll probalby have to explain this to me 3 times before I catch on!

I'm thinking about starting my rocket bell building with an outdoor oven/grill, etc., before I build a rocket bell for the house. So I'll hop over to the the oven and cooking thread....thanks again.

Ann
JMJ