I'm installing an irrigation system and I need to replace the tee that goes into my house to use one side for my sprinklers (instead of an existing hose bib). The existing installation is 3/4" copper pipe (from the meter) to a compression fitting, then the main shutoff 1", then a galvanized union 1", then the tee into the house and hose bib. After the tee, I'll have a pressure vacuum breaker, then SCH 40 PVC to the irrigation valves. When I replace the tee, must I use galvanized again? I would prefer pvc with threaded connections (SCH 80?), but this is above ground. If I wrap it in pipe insulation and electrical tape, will it be to code? This is PVC after the main house shutoff just outside the structure.

whenever I turn on any of my outside water faucets, my pipes start to howl. More water usage there, more howling. Any sugestions as to the cause of the problem? Only time my pipes howl is when I use the outside faucets