Hey all, we are converting to reverse oil fired year but I'm not sure what dimensions I need for the firebox. We have a Carlin 102 burner and will be firing at 3-3.5GPH on a 2x6 raised flue. I have the Carlin manual but it only gives the minimum firebox size but no maximum. The fire box right now is about 40" deep and I'm thinking that may be a little big? Let me know what you think. Thanks Brian