Why does the main chamber pull the flames? Heat rises, so it makes sense that the opening of the kiln would end up being the source of oxygen for the fuel after the initial few moments of the fire starting. The increased temperature of the air around the fire causes it to increase in pressure, and since the air becomes less dense as a result of becoming hotter, it rises up through the main chamber, preventing fresh air from entering through the main chamber. I kinda want to say the air is sucked in through the opening of the kiln due to the Venturi effect, but it still bothers me. The air increases in temperature, and therefore increases in pressure, it wants to escape, so it moves through the shaft of the main chamber into the open air. This movement results in a velocity. Velocity equals a lower air pressure. This lower air pressure pulls in fresh air through the opening, and into the fire, which has higher air pressure around it. I'm pretty lost on this.
https://www.youtube.com/watch?v=jpt9jvwZSEo