Raised Flue Bricking

[gunnergo4th]

I have a 2X6 raised flue maple pro and I'm wondering about how close the brick or insulation should be to the bottom of the flue pan? My box is bricked to the top of the ramp then is blanket the length of the flue pan. The blanket is basically touching the bottom of the pan. The top of the ramp goes about 18" into the front of the flue pan. So I'm wondering should I have 1" space under the pan for better heat? This was a new rig last year and I only had a couple of days boiling on it. I had about half the pan with a crazy boil then the back half with a medium boil. Any suggestions

[Potters3]

Insulation sounds right, you don't want much of a gap, you need to force the heat up into the flues

You didn't say but with the brick I am going to guess wood fired, Put in a under grate air blower ,if not already there, that should pick up your boil. With a non air tight front and boiling raw sap (no preheater or steamaway) it is pretty hard to make the whole flue pan boil hard. Usually the best you can do is hard boil in front and medium in the back.

[maple flats]

It should be between 1/4" and 1/2" gap. If you have blanket there I would suggest you leave a 1/4" more gap and then sprinkle dry refractory cement on top and just lightly mist it with water. This will harden and help protect the blanket when you brush the flues, a cleaning that should be done daily for best heat transfer. With just blanket you will have a hard time cleaning. On mine I filled the space with vermiculite insulation and then laid flat refractory bricks to cover and then to fill any gaps I did the dry refractory cement thing and misted it with water. Been good for 5 seasons so far.