I installed a Watts Series USG-B M2 Under Sink Guardian Tempering Valve in the hot and cold lines feeding the shower. I adjusted the temperature set point to the water temperature my wife wanted to shower, which is quite hot. She opens only the hot tap on the shower to get the water temperature she wants; I add a little cold. It has been in place for two + years now and works well. It prevents scalds when the hot water has been heated by the
engine and is nearly boiling. I have twice had to remove the hot water supply line to clean a small inlet
screen which plugs with lime flakes from the water
heater. Other than that, no problems.