The Gradient is not my friend...

[NTBugtraq]

So I started today;

23 brix in the drop flue just beside the float box
27 brix where the drop flue goes into the syrup pan
38 brix where the syrup should be drawn off


After nearly 11 hours of boiling, its;

32 brix in the drop flue just beside the float box
35 brix where the drop flue goes into the syrup pan
41 brix where the syrup should be drawn off


What am I doing wrong? I feel like I am doing batches rather than establishing a gradient.

Cheers,
Russ

[RileySugarbush]

A couple of enemies of a good gradient are uneven heat distribution, slow wood loading allowing the boil to drop, wide channels, big openings between channels and deep sap. If you are running over 1.5 inches, try reducing to less than one inch and keep the heat as smooth as you can with frequent firing of small loads of well split wood.

[NTBugtraq]

I've got my float as low as it will go, which is 1" above the drop flues. I'll admit to not firing every 7 minutes like some others, but I believe my arch needs to keep 3" or so above the fire or I don't get a draw that boils front to back. That means small fires...but my wood isn't tiny (most are arm sized), so firing too often fills that gap, I gotta fire less to keep the gap. We had rain today, it was my first time with this arch. I felt that made some difference (but don't know how). I have had good boils front to back, but today I was doing gyrations to get a decent boil. I had to crack the arch door to get boils towards the stack, and if the flue wasn't opened more the front channel of the syrup pan wouldn't boil...

All the wood is well seasoned, and for the most part very small diameter...??

Cheers,
Russ

[Big_Eddy]

Pictures. Wood, fire, front pan boil, back pan boil, steam plume. I believe you're not getting enough boil in the front pan so there is no "void" for less concentrated sap to move forward into. If you can only get a full boil somewhere it is better at the front. Try a test. Take two pieces of plywood and form a V and hold them in the steam plume between the front and back pans to split the plume by pan. How much steam is coming off each? I'd expect there to be slightly less off the front but at least half to two thirds as much.

If you're not getting enough evaporation in the syrup pan then there will never be a gradient. http://img.tapatalk.com/d/14/04/19/e3eha7e8.jpg

[NTBugtraq]

Eddy, I have asked before, how do you take pictures of a steaming pan...my camera lens fogs up almost instantly, and I can't see through the steam anyway...???

Meanwhile, I have made my 2nd mistake. I burnt the syrup in the front pan overnight...sigh, I know why and am ashamed...alas.

To answer your question about boils:

I always get a good boil at the front of the flue pan.
The boil is always less at the back of the flue pan.
When things are just right, I get a very good boil in the back of the front pan, and less of a boil at the front of the front pan.

So my worst boiling point is the back of the flue pan. But yesterday I was struggling to get the boil good in the front pan. It was raining, so perhaps that played a part, but I had to have my flue wide open and the door cracked a bit to get any boil at the back of the flue pan while having a better boil in the front pan.

I had intended to take pictures today as I have company coming who could help with those, but alas I am currently boiling vinegar and water to clean the front pan. I've then got to let the sap in the flue pan fill the front pan anew...I just tested it and its ~30 brix atm. Guess that will screw up the gradient again, eh?

On the bright side...I didn't burn anything in the flue pan...haha.

Cheers,
Russ

[red maples]

how do you burn the syrup in the front pan "overnight" ?

1. in a drop flue don't measure the depth by the flue pan measure by the syrup pan.

2. your not getting a good enough boil I the front pan.

3. Each time you fire your mixing your flue pan with your syrup pan. find a way to block the syrup pan when you fire. metal or wood plug. or commercial type plug will do the trick. do not pull the front plug until the flue pan is back to a boil and can push the sap back to the front pan this will increase the gradient in your front pan at draw off and lessen the gradient in the flue pan. Each time you fire you have to be ready time yourself get your wood ready to go get the wood in there and close it faster. everytime you open the doors the a cold draft hits the bottom of those pans and mixing occurs.


4. you need to make the syrup pan boil harder. either smaller wood or move the fire closer to the doors. I have forced air under fire now but even with natural air flow I think the arches are set up wrong. the top of the arch needs to be closer to the front of the flue pan. SO that's what I did. in my 2x6 I noticed there was a lot of heat loss because the top of the arch was 3/4 of the way back in the flue pan and didn't make any sense to me that the fire wasn't going through the flue properly and there wasn't enough heat hitting the front pan. So I raised the arch from the back of the firebox to a much steeper angle and the drop flues ride 1.5 inches about the bricks and start about 6" from the front of the pan. by doing this I increased the heat in the front because it needs to go up instead of back and I increased my flue pan boil because the heat needs to travel through the flues to get out.

What I did to figure this out was to put bigger wet pieces of wood in the back the of the firebox and on the bottom of the arch ramp. I noticed a HUGE difference in the boil of both the back and front pans. Give it shot it worked in mine anyway.

forget the smaller fire.... you should be filling that fire bo

[NTBugtraq]

how do you burn the syrup in the front pan "overnight" ?

Well, I stopped firing, which should mean it goes out in 1 hour, I put the plugs in between the two pans 30 minutes later, pans looked fine. I didn't check it again after I put the plugs in. So, some time after the plugs, it turned to burnt syrup...;-[

I do think I know one thing that was different yesterday, namely, I didn't empty the arch of ash. Given how much I boiled the day before, I think it made the air draw significantly less. As far as sap depth goes, I have my float as low as it will go, but that leaves me with 1.5" in the syrup pan.

As it turns out, today has been an amazing day. I've been getting 15 gph of sap, and the arch is processing 15 gph too, so I must have gotten things right. I have been firing every 7 mins, and re-split a lot of my wood into smaller pieces. On top of that I've had $115 in sales so far today...;-]

So, thanks for the suggestions folks, its made a huge difference. Oh, btw, no syrup yet today but its at +5F so far.

Back to the arch.

Cheers,
Russ

[NTBugtraq]

I know that not properly tending the evaporator while trying to shut down for the night was my biggest mistake, but I also realize now that by putting the plugs in when I did (while there was still a boil), I doomed the front pan. The back pan could replenish the evap with the sap through the float box, but the front pan had no way to get anything new, and so the boil while the fire was going out simply reduced it to ash (or pretty near). That tells me I have to either shut the fire down faster (e.g. opening the door), or put the plugs in later (after all boil is done.)

Again, thanks all.

Cheers,
Russ