Sap flow in flue pans

[Brent]

I have a question on sap flow in the flue pan. My 2 x 6 has a hood with preheater coils. After preheating the sap goes through the float box at the back right corner. Inside the flue pan a stainless tube about 1 1/4" diameter goes across the back and then forward to the front left corner where the sap is discharged. This tube is submerged in the sap. So I figured the idea was that sap would start at the left front and flow back towards the stack, across the back and then forward to the front right and out to the float box for the syrup pan.

But the divider the runs down the center of the flue pan, front to back, has a large cut out at the front, allowing the fresh sap to cross mix with the sap that is nearly ready to go to the syrup pan.

Are all the flue pans made this way ? Would it be crazy to drop a stainles baffle down to somewhat restrict the mixing and create the flow I expected.

[WESTVIRGINIAMAPLER]

Front of divider should be solid, cutout should be at the back of the pan in divider to prevent mixing.

[PerryW]

Are you saying there are cut-outs at both the front AND the back of the flue pan divider ?

If there are, you are not crazy and you should block the front divider.

[Brent]

Yup there are cut outs at both ends of the center divider. Doesn't make sense to me.

[johnallin]

Brent,
When I was at Leader looking at the Patriot raised flue setup I seem to remember the same setup and that it had something to do with reversing the flow into the flue pan.

They had a flat stainless flap, for lack of a better word, that snapped onto the top of the divider and blocked the hole next to the pipe you are referring to. The "flap" was moved from one hole to another depending on where the sap was coming into the flue pan. Looking at my new pan - still in the crate - I see the same setup as you describe. Don't know if this helps at all but it sounds like what we have here.

[3rdgen.maple]

Well that pretty much defeats the purpose of reaching a gradient in your pans. I agree with the others. I would have it welded. Out of curiosity what brand is this rig? I am wondering if it was a setup that at one time had some kind of divider so you could rotate the flue pan and that peice has been lost in time.

Johnallin beat me to it but same idea I was picturing.

[Brent]

Thanks John.

There is a flexible silicon connector between the "L" shaped tube that could be removed to dump fresh sap in the back right corner and sort of reverse the flow ... at least all of it would be back to front. Problem is how do you do that with live steam in the pan. Head scratcher.

[3rdgen.maple]

Brent you would reverse the flow between boils.

[johnallin]

Forgot to mention, mine has a tapered stainless "stopper" plug on a handle to close off one of the raw sap feed lines to use the other. I believe - it's still in the crate until I finish the sugar house - one line comes in the back of the pan the other crosses over and comes in the front as Brent mentioned. The "flaps" close off the adjacent hole in the divider to re-direct the sap.

[johnallin]

Brent,
My raw sap float box has two feed pipes going into the flue pan. The stoppers are on long 12" handles so you can change from one feed pipe to the other, under way, without getting cooked.
The "flaps" as I keep calling them are similar. Handles keep you away from the hot sap, switching over should be pretty straight forward. Will I do it? Only time will tell.

I think changing flow in the sap pan is another way to help keep nitre build-up down. I don't think it has too much to do with mixing the gradient as that is more of an issue in the syrup or front pan.

[Brent]

3rdGen

did you get any kind of a snap on baffle from Patrick ?

[WESTVIRGINIAMAPLER]

I have Welded Leader pans and on my 2x5 flue pan, I have 1.5" stainless pipes out of the float box that feeds either side of the baffle and it is always the same side I am drawing off on so the sap has to travel the farthest distance to reach the drawoff point. It comes in at the front of the flue pan and goes thru the cutout in the back. I can't understand what a cutout in the front and back would accomplish??

To reverse, I switch plugs(stainless drawoff plugs with 10" stainless handles) in float box and on syrup pan. I can reverse entire evapotor in about 60 seconds and never slow down boiling. Being a drop flue, I block off both sides of syrup pan and I draw off about 2 gallons on the light side and dump it on the heavy side. This gets the heavy coming towards the light side and then I dump the couple of gallons of light in the other side and it really pushes the heavy towards the new drawoff side.

[3rdgen.maple]

No not at all. Mine only has the cutout in the back and float box on the front left where the sap enters the pan. I told him how I wanted it built and had no desire to have a reverse flow setup in a 2x6. I did want to be able to rotate the the syrup pan however. I just think that reverse flow in a 2x6 is just about useless. Rig is just to small to make any big difference and I really don't have any issues with niter in the flue pan. When I rotate the syrup pan to reverse the flow it has made no difference and I came close to losing the pan twice from doing that so I do a cleanup an a regular basis on the syrup pan. Now don't anybody get upset with me it is just my experience from the sap that comes from my trees so it may be different for others. I am guessing however that you have a Phaneuf rig?

[3rdgen.maple]

Westvirginia it does not make much sense to me either. The only thing I can figure is that you have to physically remove the flue pan and rotate it. Lets think about it sap enters in the front to travel to the back switches sides then heads back to the front out the flue pan into the syrup pan. So the only way that cut out would work is either rotating the pan or one long pipe. The sap would enter the back, flow to the front then to the back again out a long pipe into the syrup pan. I am really confused now. But I am sticking with rotating the pan.

[JohnsSugarShack]

Just recieved my new 2x6 patriot this past weekend. And the flue pan only has a cut out in the back, the front is solid.