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Post by sneekypete on Mar 23, 2013 19:41:07 GMT -8
Hello I have rocket mass heater project that I am starting and need some other information Most plans seem to revolve around the fact you have a reasonably large area for your mass portion of the equation. I have a corner of a room that is only about a hair over 5ft and need to insure that the barrel temperatures are at least equivalent during the burn to the surface temps of the wood stove that is being removed from the room so I am able to at least get the same immediate heating effects that i had. Immediate is an overstatement as the stove took some time to heat to temp but when it did, some areas of the stove surface had 450 to 550 deg surface temps What i am needing to know is what can be done to promote Hotter Barrel Temperatures when choosing the lengths of the feed chamber, burn chamber and heat riser and also the distance of the heat riser from the barrel top and so on I read some where that the shorter the horizontal burn chamber is the hotter the barrel temps will be? Any thing any one can do will be of help as I have the book on the subject but it isn't mentioned any where Also, I don't know where else on this site to post this question so Im new to this so I apologize in advance Thanks all MIke
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Post by Dan (Upstate NY, USA) on Mar 26, 2013 0:21:23 GMT -8
I was thinking the same thing when I built mine, I am surprised how much heat is given off by my mass. I heated about 1800 square feet with my old wood stove by getting it real hot and pushing the air around with a lot of fans. With my RMH the room the stove is in is no where near as hot but I heat the whole house with it even better than with the old stove (burning 1/2 as much wood). With my RMH there is convection heating going on (or those far rooms would be cold) but so much more of the heating is taking place by radiant heat instead. Its hard to explain in words, easy to understand as I sit next to my RHM and type this. I have gotten the top of the barrel to 700F burning dry scrap pine lumber, but burning firewood it averages about 450F. My old stove ran at your temps to heat the house. I did cut holes in the bottom of the doors of the two farthest rooms and holes in the walls near the ceilings (about a square foot) to encourage natural circulation, and those rooms are super insulated (R60 ceilings, R40 walls and floors) where other rooms closer to the stove are under-insulated or average insulated. I am gutting one room at a time and redoing them. Some day the whole house will be super-insulated. Here's mine so far so you can "see", plus.google.com/photos/110857810927199793407/albums/5807337240246008481
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Post by sneekypete on Mar 26, 2013 5:27:45 GMT -8
Hello Thanks for your input I see the photos of your heater and you have a great deal more mass that I will have any room for I have a 5’ by 5’7” space to utilize I will be having the heater and barrel assembly in the middle and will wrap the mass portion around it on 3 sides mass will be about 30 inches off the floor and will have two 6" pipes running through it at 2 levels eventually heading up the original chimney Should be about 12 or so feet of direct run and 8 feet of just channels where the the flu gasses will have access too I'm trying with the mass I have which will wrap around the stove, but I need to optimize the heat output of the barrel I know there are ways to make the barrel temps hotter naturally but don't know all the theory behind it It has been mentioned in various blogs but only a word or 2 on what to do to promote a hotter barrel temp One thing that was mentioned is that an 18 inch barrel runs hotter than a 23 inch one Also the space between the heat riser and the barrel lid and the sides of the barrel and the sides of the heat riser are also of issue I just done know which will promote more barrel heat Larger opening or smaller? These dimensions will also effect the drafting ad the overall workings of the heater I have read the information everywhere I can and also have purchased the book Promoting more barrel heat is not mentioned there Mine is only a 6inch system as that is the original chimney going through the ceiling I'm worried that a system this size and with such little mass will not be enough to do what I am needing If while the stove is running it reaches and holds the close to the temps my old stove did, I will be golden Your heater is well thought through Nicely done
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Post by Deleted on Mar 26, 2013 5:51:45 GMT -8
sneekypeteIf you want more immediate heat make the surface larger. For example place another barrel atop the first. This approach will work like a bell. Surface is more important than temperature for emitting heat. Heat from a larger surface at lower temperatures will be more comfortable too.
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Post by peterberg on Mar 26, 2013 6:41:21 GMT -8
If you want more immediate heat make the surface larger. I'll second that.
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Post by satamax on Mar 26, 2013 8:00:56 GMT -8
Sneakypeete, hello, and welcome here. Didn't i see a similar thread on permies? Anyway, check the drawings i've done, and the ones from Peter, in the horizontal rocket thread. Round page seven and eight. donkey32.proboards.com/index.cgi?action=downloadattachment&board=experiment&thread=511&post=4988&key=J6FKvNFdn7Fsr9WVCSurwww.pberg.demon.nl/pictures/Batchbox/maxhorizontalrocket4.skpdonkey32.proboards.com/index.cgi?action=downloadattachment&board=experiment&thread=511&post=5007&key=lGJxgTX9l51EdiemZr1uAlso, to retain some of the heat from the barrel, and still have direct heat, you could do a brick latice, www.google.fr/search?aq=&hl=fr&rlz=1T4ADFA_frFR472FR472&q=brick+latice&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=QiGKUJaYHoaP0AX5-YBI&biw=1280&bih=553&sei=RSGKUNmeAcWw0QX4kYCACw#um=1&hl=fr&rlz=1T4ADFA_frFR472FR472&tbm=isch&sa=1&q=brick+lattice&oq=brick+lattice&gs_l=img.12..0i19.11203.11203.0.13188.1.1.0.0.0.0.110.110.0j1.1.0...0.0...1c.1.g1Kimq717nc&fp=1&bpcl=35466521&biw=1280&bih=553&bav=on.2,or.&cad=b&sei=jMJRUb-1Ocqw0AWyzYHYCA around the barrel, or even better, latice on the bottom, normal brick wall above, till the top of the barrel, or a bit more, and then open on top, so you have heat extraction in the gap between the barrel and brick wall, but radiation heats up the bricks. And still heat is taken taken away from the bricks after the stove is off. A gap of two inches would be good i think. Another way to add mass: www.permies.com/forums/posts/list/10653#100285HTH. Max.
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Post by sneekypete on Mar 26, 2013 15:19:28 GMT -8
Thank you all for your help It is fantastic you all are so helpful I will post a play by play and dimensions (if it works LOL) when I start the project I was thinking of using instead of a barrel, 10 gauge and making the overall surface larger as some one described I will read the suggestions on permies and get a better understanding of the whole dynamic of all that this entail Thank you all
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