I started off with a Sunrise Metal Fab 2x3 flat pan and arch. Over the summer I purchased a Leader 2x6 dropped flue pan set and lengthen the arch to accommodate the pans. Firebox on the arch is 2x2 and flue is 6". Firing with natural draft I was boiling about 22 GPH. I added forced draft below the fire and increased the evaporation rate to about 32 GPH. Flue temp averages around 500 degrees. One of the things I noticed both before and after adding force draft is there was quite a bit of medium brown smoke coming from the stack. This tells me that it is not burning as efficiently as possible. How do I increase burn efficiency to eliminate the smoking? I would think that this would increase temps in the arch and increase the evaporation rate.

Thanks.