Now, dielectic unions are to be used when you have joints with dissimilar metals correct? What about galv to ball valve, it being brass and all. To protect from freezing, we have water circulation loops in every house in the city where after the corp stop copper lines are being eaten up. Especially near the pump. Some people say electrolysis. We have curbed most by using brass loops although, threads cut in the brass get it too. The latest we've been using is galv. pvc has shown to be the best yet though. Any clues?