The ones I dealt with were also 24VAC systems.
Seems they were made by American Standard, or maybe Sloan... or both?
Anyway, we installed Conduit and Boxes for the devices (L.V.), along with setting a Box + 120VAC circuit for the Transformer(s).
Installed all the L.V. wiring for the valves, IR detectors and upto the Transformer(s).
Used #18 cu.
Plumbers made connections + mounted devices.
The last project where these devices were used and we (the EC) had to "Pre-Wire" for the PC, came as an unwanted FWO (Field Work Order).
Unwanted because the job was approaching Final Commissioning very soon, and there were plenty of other things to do before nasty-grams were issued!
Nevertheless, we did them properly, and still kept within the timelines of Final Commissioning our stuff!
(pulled many Rabbits out of several hats!).
Check the Web for Schematics and Details of these IR controlled devices.
I might do this too, just for additional data to post here at ECN.
All the documents per these systems have been turned over to the Clients at close-out of Job.
Like a dummy, I forgot to make copies!