Thanks, Daniel. That's what I had feared re: the metal pipe. Bricks, it is. Accounting for my elbows, the run is about 28'. I had wanted to come out of the house near to where my barrel goes, but that might be flexible.
Here we are! I've put great big monster 6"x6" beans under the already extra solid 2x8 suspended floor the span was already only about 7', and now it's no more than 3' anywhere. I feel good about that. I also took out the rigid insulation under the floor to reduce the concentration of heat in the wood.
The base is rows of bricks set on edge (4" gap), 6" apart, supporting a double layer of durock faced on bottom with foil. The whole works are spaced 4" from any wall, open front and back for airflow.
As suggested in my last post, I mortared a 4" edge of brick around the edge of the durock to contain my perlite/slip insulation, and I placed an x of brick to support my brick riser (as depicted in Evans/Jackson), and am filling the whole thing with 4" of perlite/slip insulation. I've run out of perlite and need to grab more.
That's where I stand right now, but I have a few questions:
1) Do I need to insulate under the entirety of the mass? I've understood that the dangerous temps are mostly around the core/barrel.
2) Can I use 8" stovepipe for my riser, or will that just burn out?
3) Similarly, could I fashion extra metal from excess stovepipe into the outer insulation container for my riser, or would THAT also burn out?
4) Will standard pop-rivets hold up for this stovepipe stuff, or will it melt?
5) 2 runs of 8" pipe through my mass works BEST for me, but I could do 3 if I needed to. How much more efficiently would 3 runs heat over 2? I'm in Vermont and it gets bloody cold! -20 for a week or three every winter lately.
Y'all are AMAZING. I've been weeks reading everything I can find here on the subject, and I have an idea on how to proceed with my build on a beefed-up (plenty strong) suspended wood floor. I may tweak my dimensions, but let's assume an 8" system in a day bed, 3.5' x 10' with three runs of pipe buried low in the cob. I'll be building with red brick exclusively. It was free and I'm poor.
I'm planning to space rows of brick on the narrow edge about 6" apart to create 4" air channels under and behind the stove. I'm thinking to mortar these together on the edge to allow them to conduct heat between them. My logic is that that will help avoid really hot bricks and spread what heat they absorb to dissapate more quickly.
Above the bricks - foil, shiny side down, facing the airspace, then one layer of durock.
I'll mortar a solid form of 4" bricks along the edges of the durock to contain my indulation: a mix of perlite, clay slip and a bit of Portland cement for strength. This is where I'm less sure. I want to put another layer of durock over my insulation to build on, and I think I need to support that cement board with something much stronger than loose perlite or even clay/perlite. I'd thought to add cement to add bearing strength throughout without hugely reducing insulation value.
On top of the insulation - another layer of durock, making a contained insulation sandwich with a perfectly flat surface to build on. Beyond that, I'll follow the destructions in the book exactly. Where does this plan suck?
