improving drop flue boil rate

[Paddymountain]

In my never ending quest to gain just a little more evaporation rate, I've come up with
this idea. Raise my flue pan 1/2 inch. With a drop flue and only one float, sap/syrup level remains
constant between both pans. But, if I raise the flue pan 1/2 inch, I will reduce the amount of sap
in it by almost 4 gallons. I just crunched the numbers and right now at 1 3/4 inches it holds 21.8 gallons.
By lowering the level 1/2 inch, I reduce the amount by 3.9 gallons, and still maintain 1 3/4 inch in my syrup pan.
I would think I might gain maybe 3 gallon an hour? Any gain as we all know, provides big time savings over the course of a season.
I built a preheater this year, and reduced my boil time by 24 hours. Quite a good $180 dollar investment. I'm at about 61
gallon an hour and feel I'm at a place where a little tweaking could get me to 70gph.

[WESTMAPLES]

raising the flue pan does help, i also added 1/2 in under mine 5 seasons ago and have had noticeable gains in evap rate/ constant hard boil of the flue pan. also after raising the flue pan i filled the gap under it to 3/8-1/2 in keep the heat running right thru it

[Haynes Forest Products]

The old go for more power trick. Just funning with you. Can you say with certainty that you will gain that small amount in the grand picture? Are you certain that you have done every thing else to the rig to get maximum performance out. If your over all pan boiling in every corner?

I wonder if you have a given surface area and that surface area is boiling at its maximum capacity I mean the sap is jumping out of the pans with bubbling steaming sap does it really matter if its 1.5" deep or 12" deep I would thing 12" deep would give you a better evaporation rate NOT a better fuel consumption rate but evaporation. Were really only looking at the surface and not whats happening lower down in the boiling liquid. Maybe we need windows in the sides of our rigs like a Pyrex pot.

I would think in a sense with deeper liquid its like a bigger hotter preheater at the bottom of the boiling pan.....................and maybe I'm full of crap and don't know a dang thing.

[mellondome]

1 3/4" is a lot of depth in either pan. Sure, raise your back pan, but you may get bigger rewards by lowering your depth across the entire evaporator.

[n8hutch]

If your going to go to all that trouble why not raise the flue Pan a Full inch, 3/4 of sap above your flues should be plenty.

[Paddymountain]

Lowering the overall depth would work I'm sure, but I want to stay away from the turn your back and smoke your pan scenario!
Raising it more than a 1/2 inch would probably be difficult trying to get the hoses to line up from the flue pan to syrup pan.
One other thing I didn't mention. I don't have a stack temp probe, maybe with a little tuning I could gain a couple of gph.
Always looking to improve!

[WESTMAPLES]

my front pan is usaully 1-1 1/4 in and 1/2-3/4 in over flues is also something i should have added in my first reply, i raised my flue pan mostly because i would run the whole evap shallow and was always worried if the temp spiked, i would burn the syrup pan. so adding a 1/2 in spacer kept both pans at the depth i wanted them at without adding a float box. so i looked at it like the spacer only cost me my time because the material was leftover from a job, where the float box would have cost me $$$ ... spacer was a cheap solution in my eyes, but others evap`s are setup differently so its what works for you really...

[mellondome]

What size pans are we talking about? And what is your current evaporation rate? Hood ? Preheater? Batch draws or continuous? Aof/auf? Raw sap or concentrate?



You could always come over to the dark side and go raised flue. Run the back so the flue tops are wet during boil and front is well under 1". Continuous draw on 2x6.

[Sugarbush Ridge]

I raised my drop flue 1/2" to have a little more depth in syrup pans. After burning syrup pans twice. Gives me a little more safety margin.