Evaporation rate on 2x6 evaporator

[WI Sugarpop]

Has anyone established an evaporation rate on a 2x6 with 2x4 drop flue and 2x2 front pan without any air and then added AUF? I would like to know the difference in boiling rate to be able to justify adding a blower.

[TheMapleMoose]

We use a 2x6 with a 2x4 max flue (all raised) and 2x2 patriot syrup pan. We also have a hood on the flue pan with a homemade parallel flow heater heating the sap to about 140F. We are oil fired, burning approx 4.25gph oil. We average about 45-50 gph boil rate. We can increase it by ramping up the fuel but have ran several tests and have found running at 4.25gph gives us the best efficiency. (Gallons of oil to gallons of syrup) Not sure what "auf" is but that is where we are at

[WI Sugarpop]

I forgot to mention that I have a wood fired arch. AUF is "air under fire".

[TimJ]

I think that the consensus is that insulation and air are no-brainers to add. I don't have all the threads to point to for this but from all I can remember reading here it is pretty much a cut and dried decision if you have the funds/ability to build.

From my own experience with two years on a home-made 2x5 and this past season with a new Leader 2x6:

The difference in the appearance of the boil and steam, sound, and stack temps when blowers are off compared to when blowers are on is clear. I will never build or buy an arch without a blower.

Hopefully someone will have hard numbers for you, since that makes it easy to make a decision, but I don't think you'll regret the add on.

[RileySugarbush]

It is definitely worth putting a blower on. A simple squirrel cage blower, about 1/6 HP and at least 200 CFM for under fire on a 2x6. You will boil much faster and it will be much easier to keep the rate up. You will burn more wood too.

[jmayerl]

My 2x6 drop Smoky Lake did just under 30gph last year on an old crappy arch from the 60's with enough air leaks that I could see the fire from any angle without a glass door if you know what I mean. This year it's a 2x7 (the same flue pan with a 3 foot syrup pan) on a gasification arch, I'll let you know by the end of the week what the rate is but I'm hoping for 50gph.

[WI Sugarpop]

Thanks guys for the input, I appreciate it. I think our next improvement will be AUF. I think next year we are looking at building a new arch.