Hey Matt, my wife got a rocket stove book on kindle for us to do some research and get ideas to build our own rocket mass heater. It referenced your half barrel system. We really like your half barrel system and think it may be right up our alley. We have built a 24x24 addition and thought that it would be just what we could do to heat it and make a nice bench. Other than your two videos I've seen on youtube I have not seen any plans or anything to build one. We live in the upper peninsula of mi and have some friends that have put rocket mass heaters in their home, they find it wonderful. I can't claim to know much about rocket heaters, but I'm pretty crafty and good with tools. Just looking for guidance on how to cut and where to place my tubes how to vent the exhaust out of the house. You also mentioned about lining the barrel with brick for when it burns away.
Thank you for any advice or direction,
Joe