During the past few months Nate and I and several happy Elm owners have experimented with various versions of tubes and box beams. While all systems work, some work better in different burn situations, and we are trying to narrow the choices to what works best for the majority of stoves and owners. The tried and true tubes include the most simple to make and install. We really like the “U” side mounted tubes. They have a long run to preheat the air and are off to the side and allow long fingers of flames to shoot across to the center just under the baffle. From there I built the first box beam which provides a huge reservoir of air in the center. The holes on the sides are quite effective at burning the volatile gases under the baffle. Holes on the bottom do that as well and also shoot down searching for gases as they are just leaving the logs. The most recent addition is holes across the front which wrap up and over the baffle. We also notice that the fire will choose where it wants to take that preheated air, sometimes choosing air from just the beam, and sometimes choosing air from the tubes. Often it is obvious that it is what ever is closest to the most actively burning logs. With an unobstructed view of the fire it is fun just to watch and observe the flames, whether there is lots of primary air or whether it is closed off and the fire is only receiving air from the secondary sources.