Well, they might be more of a tendency but in a nutshell, I have a water source heat pump unit that we removed and stored. It is now being exposed to freezing temps. Just NOW i realized that I never looked into freezing issues with the coil. I am curious if water has a place to expand, aka, not completely full or under pressure, will water have a tendency to expand radially in a tube or just use the path of least resistance which would be axially? In my experience, if water is in a tube but there is some air space (not full), that is no biggy but there might be sections of the heat exchanger that might be otherwise full of water but no pressure on them.