Disclaimer: Our RMH is inside of a greenhouse and is intended for experimental purposes only. Attempting to modify your RMH in the same fashion may not produce similar results and could potentially cause you larger problems. This is not intended to serve as a building guide and not recommended to replicate.
We are enlarging the feed tube side of the burn box. We fashioned a divider plate to split the feed tube. This allows us to maintain the original 7x7 shape. At the end of the night the divider plate can be removed allowing room for bigger pieces of wood. A cover will be placed over the entire feed tube to prevent smoke back. There is a secondary air intake via the ash pit.
We have another thought about this modification. The space on the right side of the divider plate can potentially be used as a small oven. Taking it a step further, when loaded with dry wood there is the possibility it gets hot enough to drive off syn-gas similar to gassifiers or biochar production. These volitle gasses have the potential to increase the burn temps in the RMH.
Update: Below is a video of the RMH running with the divider plate separating the front and rear sections of the firebox. This set-up was working ok but when we would load the back section with wood while the divider plate was in, it had the tendency to smoke back into the room. When the wood loaded in the rear section came up to temperature it would burn really well. So well in fact that it destroyed the divider plate in a few burns.
Below are 2 videos of the RMH in action without the divider plate. The audio in the video is mostly redundant. One video shows the the fire just being started and the other video shows the fire after a few hours. This set up using the lids without the divider plate works really well for my needs. Very minimal smoke back, only when loading the rear section.
Below is 1 short video from the top of the firebox as the fire is built.
A berm makes a great wind break. And we all like to break wind once in a while. Like this tiny ad: