Keep it simple

again I agree with ennismaple, making syrup in a flue pan alone is flirting with trouble. One thing I do is I use a piece of 3/16 tubing or 5/16 and siphon the nitre out of the bottom of the flues every few boils. My pan does not have a drain for the flues. I am not making syrup in the flue pan, just to be clear. I do this when it's cold before start up. I run it into a 5 gallon bucket with a pre-filter cone and then dump the clean sweet back in. A large basting squeeze bulb will fit on the tubing and be enough to start the siphon.

In cold weather I use a outdoor 100 watt lamp under the flues....good down to 5-10 degrees F.

The first year i used one divided pan and drew syrup from it. I reversed it halfway through the season because there was some nitre at the draw off end.
The second year i built a new evaporator that used 2 pans.The rear divided sap pan did not have a lot of nitre. It was feeding the syrup pan.
This year i modified the evaporator. It will still use 2 pans but now rear pan is a new divided flue pan.I expect the boil to be substantial in it.
Will the rear flue pan make a lot of nitre because of the increased exposure to flame and harder boil even though there won't be any syrup in it?

by your last post, it sounds like you'll have more of a traditional 2 pan set up?? rear pan is a flue pan, and front pan is a syrup pan (with partitions). if so, you'll be all set. By your first post i was under the assumption that you were only having one pan.... a flue pan. i think that would be a recipe for disaster. i'm not sure how well a flue pan and a syrup pan will work out with a siphon? the flue pan will boil violently (especially the front 1/2) and more than likely mess up your siphon. it might work... however, if you can find the time i would highly suggest connecting the pans somehow. you'll have much more concentrated sap/syrup entering the syrup pan and it can only take a matter of seconds of low level in the pan to royally mess things up!!

You are correct..2 pans again this year.My first post was looking for input if next year i could just use
the flue pan and draw "near" syrup from it to get away from float boxes..syphons..front pan etc?
I am also wondering about the syphon and am going to build a shield in each pan for it.It will require
a constant vigilance and i may have to transfer sap to the front pan manually.
I have friend who does all his transferring manually from a 2' x 10' rear sap pan to a 2' x 2' front syrup pan.
He has been using the 2 flat pans for years and makes beautiful syrup.He will put 10 inches of sap in his pans,
load his firebox to the top, leave and come back the next morning. He will leave it for lengthy periods during
the day as well.He is very knowledgable to say the least and has a great system!
Yes...his arch is 2 ft. x 12' and his fire box will take 6 foot logs!

I guess I was under the impression you were using two pans. Just using the flue pans to boil with could cause you issues. I would stay with two pans. Make your syrup in the front pan and boil in the flue pan. your friend that boils in the large evaporator is taking quit a chance that something isn't going to happen by keaving the evaporator unattended while it's boiling.

Do you think just using the flue pan would be hard to manage because of a more violent boil? I have installed a sight gauge this year and I would be drawing near syrup.
As mentioned it will make probably make lighter syrup. I may just reverse the pans for a couple of boils and find out.

In answer to your question Yes. Someone may correct me if I am wrong, but that is the the intent of a flue pan. To boil the sap in a hard violent, manner, to remove the water. As most flue pans have channels sap begins on one side and as it boils off it begins to become closer to syrup so it flows to the next channel. Now once it reach's the third channel this is where it would be piped into the front syrup pan and then flow thru its channels then drawn off as syrup when it is at proper density. sorry for being so long winded on the explanation. The sight gage is meant to help you maintain the sap level in the flue pan

As you get closer to syrup the density changes quicker as you need to remove less water for each percentage point. You also have a larger volume of sweet or almost syrup evaporating at a higher rate than you would in a syrup pan. If you start making syrup in the middle of the flue pan as does happen with a syrup pan or just get a little distracted it can go down hill faster and would take a lot larger OH CRAP pail to keep from burning the pan. Just remember that when you start up the next boil you will have one very large draw at the beginning and it would be very hard to add fresh sap to push it out before burning.

it does not sound like your keeping it simple. we have all done it. do your self a favor and skip the hassle, syrup pans are the cheap part? you will spend more money trying to make something work. just get a complete evaporator. just my 2 cents

Don't even entertain the idea of using just a flue pan without a syrup pan (flat pan). You would soon end up with burnt syrup.
Your friend with a 2x12 who fills the pans to near capacity, fills the firebox and leaves for hours is a burnt down sugar house waiting to happen.