The water heater has a non-adjustable thermostat that shuts off at 130 degrees.  Like most people, I like to shower at 105 degrees, and Trish likes her water to be around 115 degrees.  Here’s the thermostat with its cover removed.  The unit with the red wires is for the gas heater for the water heater, and the left unit is for the electric heater for the water heater:

Using an electrical faceplate, I fabricated a base plate that will hold my new thermostat.  It will attached under the existing thermostats, with my units occupying the center gap:

More to come!