So you can put it above ground and don't worry about freezing as long as the condensation just keeps flowing downhill?
I do not want to guarantee that, but I am almost positive that it is true. There are 3 aeration systems on our mountain that have worked perfectly all Winter.
One is my small windmill. By pure CHANCE when I initially installed that airline it was running downhill all the way into fairly deep water. It has NEVER frozen up. Had almost a continuous hole open this Winter.
Two, a new neighbor up there installed a Vertex solar rig this year. After we discovered we were having condensation issues in early November, he corrected his airline about a week later and made sure it was downhill all the way. His little Vertex rig has now had a hole open all Winter this year.
Three, our association installed a new American Eagle windmill this past October. Again, after our condensation issues they ran their line fairly quickly into deep water and made sure no low spots. What do you know, they have a hole open.
So there are three example systems I have seen with my own eyes that are not having any condensation problems while my system is shot. None of those airlines are buried. One of them is even the same brand windmill as mine! To me, that is pretty compelling evidence.
EDIT: Again, to clarify. I am still learning here. The mountain keeps teaching me lessons. I THINK I have things figured out and then get blindsided. Maybe I am wrong and something else is going on. If something else is going on I wish someone could save me the 365 days and just tell me! 
