[GH85Carrera]

Interesting idea about the shower. Back in the olden days when photography was done on light sensitive materials or processors had temperature control valves for the water. The film or the print had to be processed at a certain temperature and the water had to be real close to the chemical temps or it would cause real problems.

Out water temp valves had to have very expense valves made my one of Kimray's competitors. We had to use a all high end stainless steel ball valves made by Balon valve to turn the water on or off to get full flow, and lot leak or corrode. The name for the temperature water control gizmo was a "engine" and it was very complex with bi-metal springs and needed service every few years but we used more water per day than most homes use in a month. They cost many hundreds of dollars back in the 1980s when we bought them, and that was just the water mix valve. The ball valves were expensive as well. A tiny speck of crud like lime would make them FUBAR until taken apart and rebuilt.

You valve would have to be in a easily removable package and that is hard to do with a tile shower. It is possible, but it would be only for the ultra high end showers.

Good over the hump day.