IF I shut off the valve some sap stays in the tubing as my sprial isn't exactly perfect as it boils off it spits out.. so yes, what I do is run some water through it then it's fine.

I find it interesting some folks have trouble with this.. I literally opened a small pack of tubing, wrapped it around the stack and stuck a valve on it so I could adjust the flow. No problems ever getting the mix of flow vs. temp right, I just adjust the valve until it is running right. Maybe I got luck or it's something to do with my set up.

I'll try to remember to take a picture of my set up tonight