AOF on a small evaporator

[ecolbeck]

Based on those figures, you’ve used:

1.5 x 128 / 31 = 6.2 cubic feet of wood per hour

By contrast I’ve used:

15 cu ft/6 hours = 2.5 cubic feet of wood per hour

Having used AUF in the past, I’m surprised at how much it increased your wood consumption. That was not my experience.

[berkshires]

Based on those figures, you’ve used:

1.5 x 128 / 31 = 6.2 cubic feet of wood per hour

By contrast I’ve used:

15 cu ft/6 hours = 2.5 cubic feet of wood per hour

Having used AUF in the past, I’m surprised at how much it increased your wood consumption. That was not my experience.

Hmm... something is not right. I bought 18 bundles of wood, and they are .75 cu feet each, and they lasted about 6 hours. That's 2.25 cu ft per hour. Maybe the way I'm splitting my wood small it's not really 128 cubic feet in the wood crib, it's a lot less.

GO

[Pdiamond]

Most of the time that wood is typically a soft wood and it will burn really fast. You need to find some hard wood like beech, maple, or oak. Do you have access to any pallet wood. A lot of that is hard wood, even though it's cut small.

[maple flats]

Among other things, you need to prepare more wood for next year. Buying the high priced bundles is the most expensive way to buy wood. If you must buy wood, at least buy loose wood delivered, it will be cheaper, not cheap but at least cheaper.
I always tried and most times succeeded in having this year's wood and next year's wood as a season began.
When I first bought my RO I ended up having 4 season's worth ahead, even though I added about 700 more taps before the 4 years were finished..

[Chickenman]

To the OP, I too am interested in this idea. I'm running a Mason 2x3 and had considered AOF using black iron pipe on the outside of the evaporator and drilling through the sides for the nozzles to enter the firebox. Time and money constraints have prevented me from moving forward with the concept though.

[wvfdc4]

I'd be interested too, I have a 2x4xl. With the AUF I think I'm averaging about 15 gph firing every 7 minutes, but I am at 225ish taps this year and looking to hit 300 next year. I do run an RO but I will still take everything I can get.

[mol1jb]

Hey all,

Here is the thread for the home made AOF manifold I did for my 2x6 raised flue evap. It has held up incredibly well over the years and my welding skills are mediocre at best. It is all made from mild steel scraps I had around the shed.

http://mapletrader.com/community/sho...manifold-build

Let me know if you have any questions.

[bmbmkr]

Mine is a 2x6 raised flue. I bought used. The original owner had it bricked without mortar and claimed 25 gph on raw sap burning hardwood. I put 1" ceramic blanket in, mortered the brick, added AUF/AOF with a 650 cfm dust collector blower. I got it up to 54 gpm for about 20 min this season with 10% concentrate. I average 40-45 gph and this is a 20 ga Maple pro that was manufactured in 2008. She sat for many years un used, and thi year was the 5th season boiling. This year I added a 0.1-1 flow meter on my head tank so I could measure the evaporation rate. I'll also add that I'm boiling strictly with silver maple firewood, the next to least BTU wood you would ever thing to boil on, but my mature trees have been dying and dropping so cut em up & split em and boil with it. My firing time went from every 5 min on AUF on my old evaporator to 15-17 min with AOF on this one. This year I split the wood a little larger, 3-4" instead of 2-2.5" and it burns just as hot, a lot less labor during wood season. Stack temp running 800-900 when it drops to 800, I fire. I used all scrap 2" square tubing and only had to buy some 3" and 2" PVC for the manifold that I split the AUF/AOF air with. Definitely a time/money saver. I would recommend it, even on a smaller rig.

[tjanson]

The AOF ideas to increase fuel efficiency are very interesting as I also I have a Mason 2x4XL with blower. We run the blower at ~25% speed and get 13-15 GPH. The stack elbow glows a bit. The blower increases our boiling rate but it feels like it exponentially increases our wood consumption. I need to take some wood storage measurements but I think we used .6-.75 cord to make 4.5 gallons syrup off of 2% sap this weekend.

I had a suspicion I didn't do the bricking quite right and called up Bill Mason last week (after 3 seasons of my original bricking). He said to make the first wall after the firebox 2-3" to the pan and put in a 2nd wall 8" from the rear wall of the evap, also 2-3" from pan. I promptly got some more firebrick and just loose stacked them in to meet these specifications, as my first wall has 5" or so to the pan and I didn't have the 2nd one. I think it helped get a more even boil but it wasn't a night and day difference.

I think the 2x4XL could be improved with a traditional style pyramidal stack to put more heat into the preheater. I am going to at least change from a horizontal-ish exit to a wall thimble and external stack to a 90 degree elbow and internal stack to put more heat near the preheater. I don't expect it to make a huge difference to preheater performance but maybe worth a few degrees.

[CTguy923]

tjanson...i,m glad i saw your post, i run a Mason 2x4, but not the XL, i,m running a Smoky Lake divided flat pan on it...i noticed this year i couldnt get a boil thru out the whole pan, from the front to maybe midway back in all 3 chambers, i'll be revamping it over the summer to block it like you did yours, right now i have the front wall to about 2 inches under the pan and have the back filled with sand about 2 inches under the pan....also i run my exhaust vertical up thru the roof and my preheater pan gets to 125 or so degrees