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Post by pinhead on Jan 21, 2013 13:26:30 GMT -8
To get the pics to imbed, get rid of the "S" in https://
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Post by Donkey on Jan 21, 2013 13:59:17 GMT -8
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Post by Donkey on Jan 21, 2013 14:09:22 GMT -8
It looks like you haven't protected the floor adequately from the heat of the stove. Wooden sub-floor, right? Not only should you insulate but ALSO leave an air gap underneath. an air gap below the stove will prevent heat from accumulating, which it WILL do, insulation or not.
Remember, the flash point of wood is somewhere around 400 deg. (F) when you char the wood, it's flash point goes down to around 200 deg. (F)
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Post by matthewwalker on Jan 21, 2013 14:58:03 GMT -8
I've been following your struggle a bit, and I think it will be pretty simple to solve, but first you need to address a couple safety issues, especially with little ones about. Believe me, I love running fast and loose with these things, but you've got a couple serious concerns.
Firstly, that galvanized barrel! As I read your posts I am under the impression you are burning this indoors right now, with the door open? You have to stop doing that until you take that outside and burn it off in a big bonfire. Read up on metal fume fever, it's not something to mess with. If you didn't put the barrel over the top there's probably no cause for concern, but as soon as you cover it, you are going to get it hot enough to off gas. Seriously, someone could get hurt or killed.
Second, the paint on the main barrel. Same thing, although maybe not as toxic, but still. Stop what you are doing, and go outside and burn that paint off, please.
Okay, your issues. Smoke out the flue is totally normal when the cob base is wet, and it may be the zinc starting to gas off the insulation container. You really don't want any of it indoors, though. Like Peter has said, a vertical chimney after the horizontal run of the mass will help a lot. Run your exhaust outside and up above the peak of your roof and things will get a lot better.
Secondly, as others have said, the junction between barrel and exhaust is usually the culprit. If I were there I would rework your exhaust to couple below the barrel in an oversized plenum, making sure to make as big a space as possible. As Peter has mentioned many times, when the exhaust is coupled the way you have it there the gasses mostly are approaching from the top, so the opening is only about half useful, not to mention it's pinched by your insulation container.
Once you enlarge the exhaust/barrel junction and get a vertical exhaust I imagine your stove will run much better. Again, smoke out the flue when everything is wet is normal, and the steamy cob drying off does smell funny. Sorry to pick on your safety issues, but they need to be addressed in my opinion. Good luck.
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Post by matthewwalker on Jan 21, 2013 15:14:30 GMT -8
Oh, I second Donkey's concern as well. Those bricks aren't insulative, so they will get very hot.
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Post by satamax on Jan 21, 2013 23:23:30 GMT -8
Well, i had posted a lenghty reply, and lost it all. Things to adress, imho, side gap is too big, needs to be reduced to 1.5 to 2 inches. Can be done with sheet metal. Lack of insulation everywhere around burn tunel. Even underneath. Top gap needs to be checked too. Then, the others have stated, barrel to flue connection. And your "horendous" feed tube. sphotos-b.xx.fbcdn.net/hphotos-ash3/734466_4326677408642_159202530_n.jpgIs this a venturi, of the tunel is the same dimention as it's mouth all the way? Hth. Max.
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Post by satamax on Jan 22, 2013 2:01:03 GMT -8
Well, i had posted a lenghty reply, and lost it all. Things to adress, imho, side gap is too big, needs to be reduced to 1.5 to 2 inches. Can be done with sheet metal. Lack of insulation everywhere around burn tunel. Even underneath. Top gap needs to be checked too. Then, the others have stated, barrel to flue connection. And your "horendous" feed tube. sphotos-b.xx.fbcdn.net/hphotos-ash3/734466_4326677408642_159202530_n.jpgIs this a venturi, of the tunel is the same dimention as it's mouth all the way? Hth. Max. Ok. Sorry you lost your response. It's happened to me a few times. Not at all pleasant - but nonetheless, you started over. Thank you for that. Lets go one thing at a time here, so that I'm understanding exactly the things I need to understand. Side gap. Are you talking about between the outer barrel and the outside lining of the riser?If so, by a sheet metal fix - are you saying that we could place a rounded piece of sheet metal closer to the outside barrel and then fill the gap between that and the riser (that's already full of vermiculite and clay) with more vermiculite and clay? That sounds like a pretty easy fix. Lets start there, please. Yes, that's what i'm talking about. And for testing purpose, you don't even need to fill it. You make a cylinder the same lengh as your heat riser, with the proper gap, and fit that around the actual heat riser. Few rivets will hold it's shape. And if not filled, you can always change the gap later by slightly reducing it. It doesn't mater if it's not filled, it will fill up with gasses, have a bit of convection between heat riser and outside "wall" but it has one end blocked, so not much movement is happenig. And about your feed tube, make it the same width as your burn tunel, please. Also, insulate your burn tunel. Instead of cob, thoses concrete blocks and bits of brick, put whatever you can find in thems of making a box around it, with a 4 inch gap. For example drywall would work; or sheet metal, your concrete blocks, whatever; even wood or ply if for testing purposes. and fill that with vermiculite. Go about 4 inch above your burn tunel fill all that too, then put some cob on top to hold it, and rest the outer barrel on.
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Post by satamax on Jan 22, 2013 2:04:47 GMT -8
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Post by peterberg on Jan 22, 2013 3:10:30 GMT -8
Jamie&David, I'll try to explain it (again). As far as I do understand the layout: the stove is situated inside a double trailer, coupled to an existing house. This house is probably higher than the trailer and with a door or something like that between the house and the trailer, the latter do function as an annex. When I'm right in this respect, the larger and higher volume of the house will create a tiny under pressure inside the annex. See a comprehensive story about this phenomenon in this articles. Adding a chimney to a RMH isn't the same as swapping the mass bench with a chimney stack, far from that. The bench run could be there, the 20' or so of mass in place. As far as I'm aware your assumption is that the rocket could be vented outside with a dryer vent style exhaust right through the wall. Most of the time this won't work, because of the neutral pressure plane phenomenon, mentioned above. When the stove has to fight a negative pressure difference, it won't work as well. Now, I would think you have a single horizontal duct through the wall and the stove is running poorly. On permies.com you wrote: We got frustrated and ripped the flue off the outer barrel and lit her up - HOT. This do support my plea for a vertical stack precisely. The effect of decoupling the duct is this: the stove's inlet and outlet are all in one space, all around is the same atmospheric pressure. So there's nothing wrong with the stove itself, the problems are in the different air pressure values. That could mean this: when you're closing all the doors or whatever leading to the house and open doors whatever to outside, the stove will be running as it should, even with the exhaust duct mounted and venting through the wall into the outside air. The pressure inside and outside being in equilibrium wouldn't hinder the stove anymore. Adding an elbow and several feet of straight chimney pipe could solve your problems for the moment. This won't count as a nice chimney but it's more than nothing, so to say.
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Post by peterberg on Jan 22, 2013 3:19:08 GMT -8
Another, but nearly as important: the feed tube do appear to be larger as the burn tunnel. Or so it seems in one of the pictures. In order to avoid fire creeping up the feed, it's best to make this the same cross section area as the tunnel. Have you read the rocket mass heater book? If not, you can download it from [a href=" www.rocketstoves.com/"] www.rocketstoves.com/[/a], will cost 15 dollar. Most of the essential information is in there.
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Post by Donkey on Jan 22, 2013 10:56:17 GMT -8
I disagree with satamax on the insulation jacket size. I know that it says something other in the book (and in several other places about the web), but my experience tells me that as long as you have enough insulation for the heat riser, an "over-sized" barrel gap won't hurt anything. Looks to me like you've got some basic issues to fix. FIRST! Get the paint off the barrel and protect your subfloor from the heat. Not just insulation but a vented air gap so that heat can leave the area. Second, the feed, horizontal burn tunnel AND heat riser really should be the same cross sectional area throughout. They do better the same shape all the way through too, though it's less critical. Third, the age old bottom of the barrel, manifold issue.. See the Helpful hint thread.Fourth, what Peter said.
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