OK - We decided that with all the trees we are now tapping - Batch Boiling is too slow and there has to be another way. There is - It is called the Continuous Flow Evaporator. Dr. Tim was explaining some of the different types and there are several and improved efficiency over the years is the reason for the various designs. But - so ya understand how they work - I'll explain my rig - about as simple as a continuous flow evaporator gets and it works. My Arch or heat source is from a 250 gal fuel oil tank - but - now we are talking continuous flow evaporators. to keep it simple - picture a large flat pan 2' x 5'. Now we are going to devide this pan into sections that are interconnected so you can have a flow - section to section. In the back - toward the stack - we have two Sap Sections (or pans) 12" x 24" each. toward the front (where we add fuel to the arch) we have 3 Syrup Sections 8" x 36' each. When you first fire up - all the sap is cold and at the same level cause all the sections are interconnected with small openings. (so you get a serpentine flow effect). On the first Sap pan I add sap from my feed tank (located outside) through a tube and a small valve to my first sap section and at my last syrup section I have a draw off valve. So now we begin - we start with cold sap on first boil throughout the pans or sections. about 2 or 3 inches of sap and we boil like with a batch pan - and boil some more and as we steam away the level starts to drop and here is where it gets different. We get a trickle of sap going through our little sap feed valve to maintain our overall level (a nicer setup would use a float valve for this) and keep boiling and boiling and adding sap. Now if you scoop a little liquid from your last syrup section you will see it is getting darker and sweeter - even though it is pretty much sap at you first sap section where you add sap. As you progress and have a boil in all the sections - you will notice the large shiny bubbles in your syrup sections - draw some off from the last syrup section into a test cup and see how close you are with a hydrometer. I know guys that draw off finished syrup from their drawoff valve - I'm not that good. Close to syrup but not quite there. So You keep adding sap at one end and drawing off near syrup at the other. Continuous Flow! I left a whole lot of stuff out and I'm not pretending this is all there is to it - But - I wanted You to understand the basics of a Continuous Flow Evaporator - Hope I helped some. -----Mike-----