Got a little set back on my heels last night on Permies.com’s rocket stove forum.
It wasn’t a case of trolling or keyboard rage or anything like that. Simply my realizing that the words I was reading were in fact true and in fact, truer than my own thoughts to that point.
I designed this system to operate with a 6″ duct pipe. my first drawing offered up 2 possible routes around the new coop, heating as much of the floor as possible.
There is just no way my stove, as I built it, and the duct system I have planned ,will draw, let alone heat the room. The best solution would be to tear down the stove and rebuild it to a 7×7″ interior which would support an 8″ duct downstream. If I had the soft brick to do it, I would do it. The thing is, I cut almost every single piece of soft brick I had in order to insulate the riser. It was also recommended that I make the entire riser out of soft brick as that would allow it to heat up very quickly.
The one I build in the pottery studio across the road will be made that way.
Last night was an unsettling one for me as I was contemplating tearing down what we had spent so much time assembling. This morning while I was in the barn doing my chores, it dawned on me. I don’t need to heat the entire place. If I can pour heat into a smallish mass at the core of the structure, I’ll achieve my goal of taking the worst of the edge of the brutal winters to come. I don’t need to heat the entire room to “room temperature”. Above freezing is fine.
So, insulate around and under the mass contagious to the pipe and cut the entire thing down to 10′ or 20′ with a 15′ chimney.
And, the fire tunnel between the fire box and the riser is much longer than it needs to be. The sooner the flame is going up the riser and getting the turbo vortex going, the better it runs. With the long tunnel that is on there now, that extra length has to heat up before heating any of the riser. There is some fire physics and thermo dynamic interplay of exchanging gasses or something going on here that I sort of understand but can’t really explain yet. The “Kiln Tech” parts of my brain from back once ago are pretty rusty. Switching my thinking towards a place that I can see these stoves, not as stoves, but as kilns has changes my perspective. I’m not all the way to understanding what these things can do. Not even close to a long shot.
The question is, what am I trying to heat? Not the air. Just the wall and the floor. The wall is already dry and isolated. The mass around the pipe MUST be dry. Wet mass won’t heat up. I think it will just use the heat to evaporate away the water. The entire floor will need to be isolated away from the ground. The cement and shingles and assorted junk getting thrown into this floor won’t stop water completely. Separating the specific mass around the pipe away, from the rest of the floor, will allow it to capture more of the heat and release it more slowly. I’m thinking of it as a bench set into the ground. The side towards the barn will remain uninsulated so that it can also capture the heat and release it into the barn itself.
There is a lot of floor to fill in before I need to finalize the size shape and philosophy of this stove. the exterior goes down to the footer for the block wall, making it nearly 3′ that needs filled in. Not all of it comes from across the street, to be sure. A lot of it does though.
Back to the syrup.