Had a thought and wondered if anyone else had this thought also. I'm tapping on pretty flat land. In some areas there may be 4' - 8' change in elevation, but over all very flat. Usually I start my 5/16 line high on the 1st tree and finish low on my last tree and then may also gain a little with natural change in elevation.

My question is this. Are my lower taps further down the line more prone during freezing to having sap backing up the tubing because they are lower in the line? I'm also considering check valves for at least some of my runs and wondering if I might not be better off using check valves on the lower end drops and the leader extensions for the upper end for cost savings.

I've been rearranging my uncle's setup (which I'm taking over) so that my collection points are all in a pretty straight line, so that I might consider a mainline and vacuum in a couple of seasons or 3, but for now also wondering if my setup will work well with check valves.

I welcome any thoughts. Thxs, Mark