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batch rmh for larger building  RSS feed

 
michael Egan
Posts: 68
Location: central illinois
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I built a regular rmh for my shop: 34X30X8.5 celings. It was very efficient, used small amounts of wood but just didn't have the btu's to heat the large space. So I tore it all down and built a 1ftx1ftx3ft firebox with a side door, insulated all around and above with vermiculite, cobbed it up and it works well. I prime it at one of the cleanouts. The exhaust wraps around a big chimney: 17ft of exhaust with 7 90 degree turns before it enters the masonry chimney which is 26ft tall. It takes about 30 minutes to heat the firebrick firebox enough to fill it up with big logs, then I can walk away from it for 2 or 2 and a half hours to reload or just let it go out. I have 2 pipes going deep into the firebox to add secondary air, wish i'd have put two more. They do their job. I go through more wood but it's a lot warmer in the shop and the exhaust pipe is never too hot to touch where it goes into the chimney.

Here's my link, the video's not too good.

http://youtu.be/Q2sFParAFEc
 
Miles Flansburg
steward
Posts: 4068
Location: Zones 2-4 Wyoming and 4-5 Colorado
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Nice work michael, So you are getting a good clean burn with a bigger firebox? The temp going to the chimney is cool? Do you think you are getting most of the heat out of the wood then?
You think you need more air pipes? To make it burn hotter? Where would you put them.
Do you still get the rocketty sound?
Do you think you could build it with a big glass door, like on regular fireplaces?
Care to share more on how you built it?
Sorry for all of the questions, it is just that everything I have read so far says it has to be smaller to get the right burn.
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Michael Egan : Michael Yes, please continue to show us your build, this is great stuff and the future of Rocket Stoves !


Miles F. : Miles, if I understand correctly, the idea is to get the modified/bigger Burn Tunnel very hot so that the next batch of wood is ignited and burns efficiently,
some additional air is needed to get a good clean secondary burn.

Having said that I'm way!!! over my head ' Bells ', Peter channels/secondary air , Trip wires , Pozzolan Chimneys , Trip Wires , Batch Loading(s) , and Thermal
Benches on two different floors , Damn !! You guys are going to leave this old duffer way , way , behind !!

For the good of the Craft, Be safe, keep warm, PYRO Magically - Big Al
 
michael Egan
Posts: 68
Location: central illinois
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Miles Flansburg wrote:Nice work michael, So you are getting a good clean burn with a bigger firebox? The temp going to the chimney is cool? Do you think you are getting most of the heat out of the wood then?
You think you need more air pipes? To make it burn hotter? Where would you put them.
Do you still get the rocketty sound?
Do you think you could build it with a big glass door, like on regular fireplaces?
Care to share more on how you built it?
Sorry for all of the questions, it is just that everything I have read so far says it has to be smaller to get the right burn.


It burns really hot right now-- the cheap thermometer reads 700 to 1100F on the top of the barrel. The top glows red so I'm not trying to get it any hotter.
The burn chamber in this stove is more like a traditional rectangular firebox but a little bit longer--3ft- and narrower. What makes it work is when the firebrick get heated up really hot and then the fat logs burn but their thickness cause them to burn more slowly than small wood pieces so they don't over consume the air. It's basically like a regular woodstove but much hotter but I think the barrel and heated riser (triple wall 8 in) are helping with the draw and probably the physics of rapid temp decrease are in play as well but i'm not that well versed in that academic area. The part I'm still playing with is the air intake. As I said in the video I can't put little dry pieces in when the box is hot because they will vaporize and there's not enough air to burn the vapors: it smokes. If you watch the part when I put the logs in they actually start flaming--not smoking-- right away so there was enough air in that mix. The two tubes at the bottom of the rmh channel air deep into the box and enter very hot so you will see the area where the fire is going up the vertical burn chimney is a huge bright mass of flame-- clean. There is some sound but not as loud as the regular rockets, I think because it moves a little slower. I would add more tubes maybe one in each corner, 2 in pipe instead of inch and a half. Also, I want to try making a firebox like this from a mold like "Braudio" has been doing.I would like to add glass to the door or window, probably on the next one I do. And you notice I used half inch rebar to hold up the firebricks above. They get red hot and probably lose over half their strength, they seem to be holding up ok and there is also a wire mesh embedded in the cob above (vermiculite, then the mesh and cob) but I still don't stand on it and I think it's probably a structural weakness having rebar in the firebox.

I just uploaded some more videos of it which is mostly how I start it and a little more visual of the wrap around exhaust-- 6 90s which is a lot but I built the chimney before I knew about RMHs. I have pictures of part of the build i'll post when i get time.
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Michael E. : In facebook we have the 'poke button' to remind missing friends that we think! that they said!,,,,, 'hay i think you were 'sposed to' !

You have showed us just about the best 'batch loading' rocket stove Permies has seen! This,followed by 10 days of nice weather. When its over 65
in the shade, who wants to run a wood stove and document results !

But, but, but You promised Anyway, we are awaiting more from you ! Please ! For the good of the Craft! Be safe,keep warm, 'just not too comfortable'
PYRO - Logical Big AL - Comments solicited and welcome A.L.
 
Peter van den Berg
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Location: +52° 1' 47.40", +4° 22' 57.80"
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allen lumley wrote:Having said that I'm way over my head ' Bells ', Peter channels/secondary air, Pozzolan Chimneys , Trip Wires , Batch Loading(s) , and Thermal Benches on two different floors, Damn! You guys are going to leave this old duffer way , way , behind !

I consider myself 'at age', being retired over two years ago at the ripe age of 65 years. My dabbling in rocket stove territory started about 6 years ago, diverting from a hobby designing and sometimes building of masonry stoves.

So Allen, please enlighten us, how old of a duffer are you actually?
 
allen lumley
pollinator
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Michael Egan : I missed it and only caught it on a re-read , what kind of cheap thermometer,that reads to 1100F and where did you get it ! any chance of more pictures ! Big Al !
 
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