I have started building my RMH I'm using a prebuilt chamber,I've added firebrick to the entire inside including roof. Have a fored air ducts 4 small in top of fire chamber and was going to use the small fan to force air into chamber from the top down. Pushing the fire out the lower bottom of stove. (fire would be burning the wood from bottom to top) hence ashes fall straight down into pan with the exhaust beign above them. The fire chamber would be outside on the porch with the exhust coming throught the wall in a tripple wall pipe going into my gassification chamber and heat exchanger. My idea was more wood to burn at a slower rate. I'm heating a big house and am gone to work for 10 hours a day. Would like contunious heat. I've factored the size of my stove and BtUs of wood and I have more than enought room in the chamber. I know this idea of the upside down burn goes all the way bak to Ben Franklin. But with 12 volt fan and the gassification chamber is it now fesiable? I need to finish this in less than 60 days as it gets cool in NeKansas by then. And I have to have heat.
What you're trying to build is called a "gasifier stove." They're very different from the "rocket stove" designs discussed on this site. Both systems are designed to produce intense heat by burning the volatile gasses released in wood smoke. The main differences are:
1) Gasifier stoves are much smaller than rocket stoves - suitable for camping rather than for a permanent living situation (with larger sizes being too dangerous to attempt); and,
2) Gasifier stoves must go out before more fuel can be added. With rocket stoves this is unnecessary.