Confused with a divided pan setup?

[brohnson]

I totally understand the whole flue setup pan but I am all new at this and I don't understand how the divided pan works. I know the cold sap goes in on one end and than comes out syrup on the other end or close to syrup. How does the raw cold stuff flow through the compartments? Just it do it on its own or do you need to push it through? I want to make one but I don't understand how it works and what the best way to make one is. So any plans on the best types and some explanations on how these work would be awesome.

Thanks, Tim

[saekeaton64]

Divided pan ( syrup pan) is usually used in conjunction with a raised or drop flue pan. The flue pan goes in the rear and the syrup pan goes up front. There is a float that is on the side of the drop flue or between the raised flue and syrup pan, the float is to maintain a constant level of fluid in the pan at all times. As water is evaporated or syrup is drawn off the level in the pan drops slightly and the float lets new fluid in, this is the driving force that makes the sap flow through the sections in the syrup pan. As for a design there are many options and all have perks. Some allow the user to draw off either side by reversing the flow. Most syrup pans for a smaller evaporator have 3 sections running either with the length of the arch or perpendicular to the arch ( user preference). Hope this helps.

[brohnson]

K, but what makes the sap run through the channels in the pan? Why wouldn't the whole pan be the same temp all the time? What makes it vary its temps so much from one channel to the other?

[Super Sapper]

In a divided pan the sap from the flue pan enters one end and as water is evaporated the level will get lower. As the level goes down fresh sap comes in and pushes the older sap forward. As the concentration rises so does it's boiling point, so the most concentrated (oldest) will have the highest boiling point which is at the draw off.

[brohnson]

K, this is starting to make great sense here. When do you draw it off? When its 219 or do you draw it off and finish it over propane and it you do than what temp do you draw it off at? Thanks for the info!

[saekeaton64]

When starting out all the sap in the pan is the same. As it cooks water is evaporated and the sugar content in the sap starts to increase, this sap is thicker. The fresh new sap that is added pushes this denser sap further into the pan to maintain the level set by the float. This is what causes the flow through the channels.
The reason for the difference in temp. has to do with the concentration of sugar, the water in a sense limits the temp in the channels as the water is removed it allows the temp to increase. There is a lot more that goes into the thermodynamics of the whole thing but that is the jist of it.

[psparr]

K, this is starting to make great sense here. When do you draw it off? When its 219 or do you draw it off and finish it over propane and it you do than what temp do you draw it off at? Thanks for the info!

You can draw off early and finish or draw syrup it's just preference. If you don't have a hydrometer you should get one. Great investment even for a cheapskate like me. It's syrup at 7.1 degrees above the boiling point of water. Water will boil at different temps for a variety of reasons.