However I need to. LOL Haven't fully worked those details out yet.

It's for my cabin. I was originally going to tie Lutron into Nest to maintain a home/away mode. Our experience with Nest isn't great. Random notifications when they were set them to not send, having the place to switch over to the Home mode even though nobody switched it and we weren't in town. So I don't think we will rely on Nest to initiate Home/Away control.

We will either install a manual switch or a Lutron switch that will control a relay, transformer, or whatever we need to operate the valve.

Many would argue that if you lose power, you'll lose water. The place has a well pump so losing power means no water regardless. Plus with a boiler valve, you could manually open it. IDK