Flues in the Fire box?

[lyford]

I just received my new 2x4 smoky lake hybrid pan and am designing the arch. My first question is what portion, if any, of the drop flues should be in the fire box. I have read some posts where 6inchs should be in the box and have read others that say none of the flue should be in the fire box. On this pan the syrup section is 18" deep and the flues are 30" long. Any thoughts?

[madmapler]

Typically the ramp goes up under the flue pan a little to allow the flames/heat to flow freely under the flues. I'm guessing this is a raised flue. If it were drop flue then it wouldn't be necessary. 6" sounds about right although it might be less. I have little experience with smaller evaporators. Maybe contact smoky lake.

[Pibster]

I have a Smoky Lake Hybrid pan also. My firebox ends at the start of the flues but I'm considering moving the flues back a few more inches. I am getting a huge boil at the front of the flues and not enough in the syrup section.

[MunsterMapler]

I also have a 2x4 hybrid I think I have about 9 inches or so exposed to the flame. IMG_20160316_172236263.jpg.
Here's a pic if that helps.

[lyford]

Thanks for the input guys, I also am waiting to hear back from Jim at smoky lake to see what his thoughts are. At this point Im thinking I'll have about 6-10 inches in the firebox. Haven't started building yet though. Munster I saw your youtube videos of the rig in action, awesome, can't wait to get mine boiling!

[Waynehere]

I have a 2x6 and building a new arch as well. Most of the research I have been doing is showing 30-50% of the flu's exposed to the flame. I opted for the 50% this time. The idea is that there is more heat from the radiant light then the hot gases flowing through them.