Came across this nifty item out on inspection this last week. The house was new construction in Oro Valley a suburb of Tucson. Turns out these whole home mixing valves are finding their way in new home builds in some townships. I was curious on its function and wanted to share my findings. The mixing valve has 3 distinct benefits:
1. Allows for higher temperatures in the hot water tank, thus extending available hot water.
2. Prevents bacteria growth ( Legionella ) when the hot water tank is set to 140 to 180 degree F.
3. Less fear of scalding water at the shower, tub, and sink.
** Source Honeywell
Honeywell.pdf