First thing: insulating is one of those things that adds initial cost but will probably pay for itself within a month in these things. Especially on or in the roof. Roof insulation should be > 3x wall insulation. Also, caulk those joints!

Open flames are a shitty, inefficient way to heat. You want to be heating a centralized mass. Also radiant is preferable to convection. Also, fumes. Also, sleeping next to open flames.

You might check out high efficiency woodstoves. Basically just a metal box with a flue in back. The principle is to harness as much of the radiant heat of the fire as possible. Most of the convective heat needs to go out the chimney anyhow with the smoke.

South facing windows will help more than you might think. Bonus points: let the sunlight soak into a dark colored, massive object. The sun comes in shallower than 45 in the winter, so you can shade in the summer. Two layers of acrylic with caulk. Thicker is better but more expensive.

There is a type of burner whose name escapes me, that is basically a wick running through a perforated metal tube that is used with alcohol fumes. Compressing air for a burner makes it pretty inefficient, no?

I love this project though- you all have made tremendous progress.

glad to see things are progressing nicely….

u had a chance to run a batch thru the reactor yet?