I started a thread about this in the hot water tank section because my TPR was leaking but but after checking the pressure. it might be worth mentioning in this section, I have a closed system (there is a backflow device by the water meter and a PRV next to my shutoff inside the house) and today I hooked a pressure gauge to a couple of different faucets and it read 60. I attached it to a hose bib outside and left the water on without opening any other faucets and after an hour of it being on, the gauge rose to 120. As soon I relieved pressure by opening another faucet it went down to 60. Since the gauge is reading 60 initially, does that mean the PRV is working and set at 60? I do not have an expansion tank on the hot water heater. Would that cause the pressure to rise that much? Any other thoughts?

Hello, I purchased a water softener cheap and looking to install it. I have a question about plumbing it in, which line should I tap in to? Thanks