This is just for fun and contemplation, I'm not sure if it's true or not. Our cooking stoves use something like 2 pounds of wood per hour. That's around 17,600 BTU's. One third of 2 pounds is .66 pounds of wood. Maybe we should be only pushing .66 pounds of wood through that stove per hour because the pot in that configuration does not absorb the excess heat.
Combustion occurs in a smaller, well insulated combustion chamber.
That adds up pretty close to our original number of 5600. I'll report back Thursday night.