Isolating Flow-Thru Evaporator Pans - A Question

[Ausable]

When I assume something - I usually get in trouble. So my question is - On a Factory Built - Flo-thru Evaporator - Can the sap pans and syrup pans be isolated from each other? Like when You shut down and leave the pans sweet till the next boil. I have a home built 2'x5' flat bottomed flo-thru with two 12"x24" sap pans and three 8"x36" syrup pans - I can insert isolating plugs between the last sap pan and the first syrup pan and between the second and last syrup pans. I find it real handy to have this ability and have assumed all evaporators had this ability in some form or another. But - now I don't know - could you answer my question and I appreciate it.

[Bucket Head]

All raised flue pans have shut off valves. They have to have them because the sap level is higher in the flue pan. I'm not certain on a drop flue, since both pans are at the same level. Only one float on those, at the rear pan. However, I would think there would be a shut off between the two. Or one could be added so flow could be stopped in an emergency or when the front pan is removed for cleaning.

Steve

[maple flats]

As Bucket said, Raised yes, drop flue sometimes. As long as your 1st boil is at least 3 hours of good boil you have enough concentration to protect against freezing. You will get some slush on top but it will not freeze solid. This being said, If I get a extended freeze after first boil I drain the pans and pump it back in next boil. If a freeze will only be 2-3 days I just watch it, if the slush freezes more than 1/2" deep, I build a short fire, warm the bricks for 1/2 load of wood to warm it and then let it go out again. Each time I do this it gives me an extra day protection. However if the temperatures drop to single digits (F) I drain the pans.

[wiam]

Dave, I think you will find no need to drain evaporator for cold temps with concentrate. 2 years ago my ro was over 200' from the sugarhouse and I left concentrate in the line and it never froze, even below 0. This was 8-10%. I know it is best to run some permeate through to get sweet out of ro but this seemed to be best way to keep from freezing. Last year I had a shorter run on top of ground so I did same thing. This year concentrate line will be underground so I am not decided yet.

[wiam]

Ausable, I have not seen a commercially made evaporator without some way to isolate (valves or plugs) I prefer valves as I have seen plugs leak by, but I have not changed mine over yet.

[Ausable]

Thanks William --- I've looked at many pictures of Evaporators and was never quite sure. Always thought they would have - but - that was an assumption on my part - so figured I'd better ask and know for sure - rather then passing out incorrect information - thanks again ---Mike---