I pray that the season finds you all hale and hearty.
The rocket stove in the barn has come to a sputtering sort of life. The experiment felt a functional failure with my first attempt. The chimney stands over the peak of the barn and yet the draft barely invited more than an oozing flow of smoke flavored steam. Insufficient draft causes the wood in the feed box to back burn up the length of the material. This, of course, then fills the room with a lovely choking cloud of smoke. The irony is that I set the large bank of windows before I set the chimney. Baaaaaah! I’m going to have to dig this monster back out of the ground!!! The only think I can think of, at the time, is that the barrel head is too close to the top of the riser. We are talking about HOURS of work with the possibility of fracturing the soft brick. uggggg
But as I’m sitting there, casting my mind inside the guts of the thing, I remember the coating of moisture in the duct around the clean-out. I know this thing is practically soggy inside. Even months after putting it together. If the system had been set up through the roof all those months, then maybe it would be a bit drier. I can almost feel the steam cloud in the riser. Because think about it. This thing depends on fluid dynamics. The hot hot flame makes the air increase in volume and go up. New hot air leaps up from the flame just below the slowly cooling air that left the flame just a moment ago and already new hot hot air comes off of the hot hot flames and expands and goes up, pushing the cooling mass of air above it up the riser. As the air begins to lose it’s heat load into the thermal mass of the riser, the firebrick in the riser begin to displace the moisture embedded in every crack and fissure in it’s surface. Water cools things super fast. This is why fire fighting is done most often with water rather than sand or mashed potatoes. The explosive boiling process eats up the heat in the air very quickly. What all this means is that the energy that should be going in to shoving the air along the system is suddenly tied up in that evaporation. Then too, hot water, in the form of steam, expands into a vastly larger volume than air heated the same amount. This confuses the “normal” flow.
Confusion was how all this left me. Crestfallen, disheartened if you will. But, remember, the room I was sitting in was filled with smoke. Which means carbon monoxide and all that unburned fuel. Not the healthiest of environments. I fled the scene once I was sure that the stove was out.
I went to words of the legends. I looked into the TROUBLESHOOTING section of rocket mass heaters by Ianto Evans and Leslie Jackson
Here is the direct quote from the end of the bit on ” Stove smokes into the house”
“The first time you light your new stove, don’t expect immediate success. Don’t be downhearted if it smokes like crazy and it’s hard to get a draw. With any new masonry stove which is still cold and wet when you first fire it, there will be an adjustment period. Use the primer, light it up with the driest, thinnest wood you have and be patient. It may take several hours for it to start burring really well.”
And this was followed up this morning by this reply on a rocket stove forum at Permies.com.
Charles; When I have a wet core & mass I expect trouble. My first core and mass took 4-5 weeks of hard burning before it was truly dry and heated up. Be patient keep burning .. it will get better. I keep a small electric fan on hand and when it starts to smoke back I blow down the feed tube…. works great as long as you are in the room, the fire will quickly start roaring . Take away the fan and in a few minutes or an hour it may try back smoking again. Just keep giving it extra air sort of a turbo effect, make that dragon roar, get it hot before too long you will start to see an improvement.
It has simply been too long since my days as a kiln builder. And it’s all too easy to get caught in the moment and think, I FAILED. But alas, no. I just need to jamb a bunch of wood through this thing. It’s a living thing, fire. Well, it’s sort of alive. Look into an Anagama or Noborigama when they are at temperature. In that rarified heated plasmatic environment, fire gets weird. As I see it, the kiln is a temple to flame. Far beyond what most people see in your standard wood stove. Most of them rarely achieve 1300 F. That fire sin’t allowed it full potential. In order for the flame to achieve it’s potential, that fire house has to be built right. Sometimes this can happen inside of a burning building. I remember a documentary of the Branch Davidian Compound Massacre in Waco Texas back in 1993. The long and short is that one of the 7 survivors was inside of the complex as it was burning. He described the flame as a snake, moving through the rooms, hissing as it went. Seeking food and oxygen. Roaring at times. Having seen it move like a river, I believe him. It’s these little “fire rivers” that the rocket stove harnesses. This is what kilns (and this is a tiny kiln) are made to do. Create a space for flame/heat/fire.
I give thanks to all my relations.