since I've built my boiler, 3 years ago, I've been trying different things to attempt to get some secondary action in my firebox. This morning some progress has been made. For those that do not know my firebox has only the top half submerged in water. The bottom is full of refractory brick and cement. This morning I installed a false ceiling in my firebox to trap the heat. I used the side of 55 gallon drum and stuffed it in my firebox to shield the top of the fire from the water jacket. Then i plumbed air through my fire grate, which is made of stainless steel pipe, up over the fire. The piping has many 3/8" holes in it over top the fire. Theres a second fan that blows air into the secondary piping. Here's my water temp and flue temp about 45 minutes into the burn. Boiler has 120 gallons, and This is from 135°F and charging 750 gallons storage at the same time. Highest flue temps i saw was between 400-410°F. And my stack heres a some videos of my burn this morning. The first is shortly after things got warmed up, the second is shortly after i tossed in a few more pieces.