help with new evaporator set up

[Danthemapleman]

Greetings. I jumped from one of Bill Mason's 2 x 4 flat pans to a 2 x 5 with raised flues. I'm psyched about the new rig, but have a question. I had to brick the arch and I believe I did a good job. But when the fire is really going there is a massive boil at the top of the ramp. But the rest of the pan -- the back half -- is rather quiet. Should I raise the insulation higher? Why is there an eruption at the top of ramp, but not so much beyond that? Thanks for any help!

[maple flats]

It will boil hardest at the top of the ramp. How much space did you leave between the bricks and the bottom of the flues? What size stack?
On my 3x8 raised flue I have 1/2" between the brick and the bottom of the flues, that forces the extreme heat into the flues. When boiling at first the top of the ramp will boil hardest, but if you fire it right the rest will boil hard too, just not quite as hard as the top of the ramp.

[Danthemapleman]

Thanks Dave.

The stack is high -- maybe 6 feet inside the sap house and another 8 outside. I'd say I left maybe 1" between the bricks and the pan -- so maybe I'll tighten that. I'm using that insulated pellets (big bag -- can't recall the name), so I'll add some more.

Also, the thermometer on the front pan -- the draw off pan -- never gets near 219. I guess that's because it's in that little pocket -- by the draw-off valve. Any thoughts on how high I should take that before drawing off? Is this common?

[motowbrowne]

Thanks Dave.

The stack is high -- maybe 6 feet inside the sap house and another 8 outside. I'd say I left maybe 1" between the bricks and the pan -- so maybe I'll tighten that. I'm using that insulated pellets (big bag -- can't recall the name), so I'll add some more.

Also, the thermometer on the front pan -- the draw off pan -- never gets near 219. I guess that's because it's in that little pocket -- by the draw-off valve. Any thoughts on how high I should take that before drawing off? Is this common?

My gauge usually doesn't get that high either. I take off at 31 degrees Baume and my thermometer usually reads around 216. I just note where it is the first time I draw off for the day and start paying attention to the hydrometer when it approaches that number for future draws.

[maple flats]

If you are using vermiculite pop corn, it can get sucked up the stack with a good draft, you want brick over the vermiculite. That's what I have, my arch is 9 or 10" tall, I filled it so a flat layer of bricks just left a 1/2" space.

[billyinvt]

I have two suggestions. Create some "friction"under the flues. It will get the heat to jump around a bit rather than fly up the stack. As far as getting a hard boil up front, it is important to load your firewood right up under that part of the pan. I always keep a milk crate full of short wood to lay horizontal across the front.

[sg5054]

I bricked to within a 1/2 inch of the flues for their whole length. The arch is all brick, no vermiculite or other filler. Once that all gets hot, you have that thermal mass to help maintain the firebox temps.