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massive rocket heater  RSS feed

 
debi cooper
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Hello, I am interested in finding out if a conventional wood burning fireplace can be converted to a rocket heater to heat an entire house?
If so, I would like to find a local builder that has experience converting fireplaces to rocket heaters. I live in San Francisco Bay Area.
Do you have recommendations?
Thank you kindly,

--debi
 
kae scrat
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I'm researching for the same kind of "rocket fireplace". But I would like information to build it myself.
 
Adam Stjohn
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This question has come up a lot. Look around on the forums for more info.

Check out this page on the forums: " http://www.permies.com/forums/posts/list/40/2558 "

where some people talk about this:

http://www.iwilltry.org/b/build-a-rocket-stove-for-home-heating/

There are definitely more posts which address this idea.

Disclaimer, I'm not an expert; but anyway: this is what I seem to remember about the issue:

Truly this would be a 'massive rocket heater,' and not a 'rocket-mass-heater' --- why? I'll explain

At the heart of the general design of rocket-stoves, there is a 'heat-riser' (an internal chimney, inside the barrel). The hot gases burn up through this and then hit the barrel. The barrel acts like a radiator and cools the gases, which then drop down and out the exit. All of this creates a strong draft.

It is that strong draft which makes possible the horizontal exhaust system, around which an earthen-'mass' is constructed to reap heat. By the time the gases are exiting the system, they have 1) gone through a bunch of piping, the friction of which has already put quite a drag on the draft and 2) the gases have cooled down a lot (the heat from them has gone into warming the bench).

Now, for many rocket-mass-heaters it is recommended that the exhaust system finishes with some sort of a vertical chimney. The warm gases love to flow up the vertical chimney; This helps with the draft, as long as 1) there hasn't already been too much pipe with too much friction and more importantly 2) as long as the gases aren't already to cold. In other words, if the gases have already gone through the mass (which has reaped a lot of their heat), then they may be too cool to properly move up the chimney. So this all depends on, 1) what temperature the exhaust-gases are, relative to the outdoor air and 2) how long the chimney is.

If your chimney is too long, then the gases will cool too much before exiting, and this will screw up the draft.

In any case, you should be able to run a rocket-stove through a conventional chimney; that is, you might have to subtract the 'mass' from the equation. This way, you may not have a mass, but at least you'd have a super-efficient rocket-stove.
 
kae scrat
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This is a great answer. I'm looking for a radiating rocket stove, without the mass. I'ts obvious that you can't feet the mass in a tight place like fireplace.
Thanks for links.
 
David Konkle
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Location: NW Arkansas
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Why not just build a RMH on the existing hearth and exhaust out a nearby window or wall, using the masonry of the fireplace as part of the mass?

I'm not sure if this has been discussed before or not. It obviously would not be practical in all situations, but could work in at least some situations where the builder wanted a less permanent installation. If it could be done, I can imagine the feed and barrel sitting in front of the existing fireplace (using the existing chimney as the fresh air inlet) and wrapping the RMH exhaust as close to the existing masonry as feasable before exiting through a nearby window or wall.

Biggest problems I can forsee is not having a nearby exit for the exhaust from the RMH. May not be as simple as it seems, but could be workable in some situations.
 
Adam Stjohn
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Yes, I like Konkle's addition here.

Furthermore, rather than running it through a window, why not make (cut) a new exhaust-exit in a wall? Doing so wouldn't be very difficult, would it?

Secondly, CAUTION: Consider the location of the exhaust-exit (say, through a window) in relation to the location of any input-entrance (say, the old chimney)... What I mean is: be careful not to place the exhaust-exit too close to a place where the exhaust could draft back into the house or system. Make sense?

I mean, all indoor woodstoves (rocket-heater or not) pull air into the house, through windows, under doors, cracks, etc-- If the house were perfectly sealed, then the stove would not be able to send any exhaust up and out the chimney! (Exhaust is going out, fresh air needs to be coming in.) So anyway... Remember to consider the location of the exhaust in relation to the location of any input(s).

 
Satamax Antone
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laura sharpe
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Not particularly sure what you want from the conversion, did you want it to still be a nice looking fire place but to burn wood more efficiently? Did you want to include a mass into the fireplace so that the heat does not go away immediately after the fire goes out like most fire places? Are you out to save money on making a new heating system by incorporating what is there already or rather trying to to get the look of the fireplace while using it as a more efficient heating system.

Not sure if i said all that right but i think you get the idea. If you could like to have a more rmh like system but would like to have the look of a conventional fireplace, I suggest you look up the russian stove. They can be made to look much like every other fireplace but they use bricks as a mass to take the heat from the exhaust to radiate back into the house for hours or even days.

the picture i saw of the rocket burner exhausting up the chimney burns the wood more efficiently but more ugly and is much more inexpensive than rebuilding the entire fireplace but loses the advantage of the rmh...the mass.

www.dnr.mo.gov/pubs/pub781.pdf is a modified russian stove. I love these as much as i love rmhs they look completely different but work on the same principle, take all the heat out of the exhaust and store it in a mass.
 
Ernie Wisner
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do you mean like this one https://lh3.googleusercontent.com/-h--7R-1I_04/T9DdIndZN6E/AAAAAAAABuw/vlYsuo63hhY/s290-c/20120607
 
gani et se
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Location: Douglas County OR
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Ernie,
What are we looking at in your pic? a (rumford??) fireplace with a RMH to the right of it, or something else?
thanks,
Gani
 
Ernie Wisner
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the RMH is ducted through the back of the fireplace 3 passes to heat the huge mass and the rumford is the preheat and entertainment fire.
just kinds thought that was an answer to the question.
 
gani et se
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Location: Douglas County OR
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think you're right about it answering the question, thanks for the explanation.
 
Linwood Bridges
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Hi, I'm new to the forum and have been researching rmh for a month or so. Just a thought...could the chimney be sealed just out of sight but allowing the exhaust pipe to exit up the rest of the chimney? If the heater were mostly bricked in with some area exposed for quick heat, then wouldn't the bricks then become the mass? I'm sure something could be fabricated to decorate the front if someone put some creativity to use.
 
Ernie Wisner
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not sure what you mean Linwood.
the barrel is the radiant part of the stove and it needs to be able to radiate a bit to help drive the system. but the ducting can be housed in brick with Welsh masonry fill for the conduction properties.
 
Linwood Bridges
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So if the barrel doesn't radiate heat away fast enough then the system won't work as well? I didn't know if keeping half of the barrel out to radiate some heat away, and the other half mortared in that the mass of bricks would get hot and give off heat long term after the fire was out. I am new to the idea, so I apologize for my lack of education on the subject. Thanks for increasing my knowledge though! Downloaded the book online and am scrounging stuff already. I look forward to learning and building one sometimes... for my garage to start with.
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