I need to find

[Bernie/MA]

somebody near central Mass that boils with a six inch stack ,woodfired. I'm building a preheater that consists of a spiral trough that wraps around the stack for the sap to trickle down and I'd like to test it. I used to boil years ago. Now I just tinker in my welding shop. Thanks in advance.

[Sugarmaker]

These can be a little finicky. Stack temp comes to mind as one of the uncontrollable variables. I have heard you can get vapor lock due to high sap temps. I have seen some work but depending on the flow rate they may not build much temp. Good luck with your tests.
Regards,
Chris

[Bernie/MA]

I don't expect vapor lock in an open trough to be an issue.