How Close To Bring Fill To A Drop Flue Evaporator

[Bruce L]

Hi all,have always worked with raised flue evaporators,am currently setting up a 2 x4 Leader Supreme for the young lad on my school bus. Got the bricking done in the firebox yesterday,have to just finish back end next warmish day. Thinking 1/2” under the flues,and maybe 3/4” under the flat pan portions on the two sides,then drop off to 2” clearance at stack collar. This is natural draft also,would I be setting it up too tight to perform properly?

[ecolbeck]

1/2" under the flues sounds good. I would then continue at that same level under the stack. I don't think there's a reason to change levels between the flue pan and the stack.

[maple flats]

Directions on the ones I have seen all have the area at the back of the pan drop down, where the stack then goes up. I would not have just 2" under the stack, I'd do about 4" there. From the firebox end I'd make it 1/4 to 1/2" max under the flues and your 3/4 under the flats should be OK. Then just an inch or 2 before the back of the pan, drop down 4" and continue that to the back of the arch. My suggested measurements should be to the top of fire bricks, use regular bricks if firebricks are not in the budget.