Hello all, new member here. I am an operating engineer of a 10 story commercial office building in Silver Spring, Md. It's actually right across the street from the Discovery Channel Headquarters building, which is neat. Anyway, I'm trying to understand the affects on the freezing point of water under pressure and velocity. Basically I try to keep my pipes from freezing by leaving the pumps on when the outside temps drop below 32*F. This keeps the water flowing under a pump pressure of approximately 25psig. I've searched and found phase diagrams of pure water, but I have a hard time comprehending them. Can someone help me understand this better? Thank you.