The following lines were added (+) and removed (-):
When a mixing valve is installed on the hot water heater, it will open to mix in a little cold when the temperate of the hot water exceeds a certain threshold. The homeowner can inadvertently have a hot water heater temperature set higher than this threshold. The valve then is constantly allowing some cold water to flow into the hot water line to compensate. This results in wasted energy. The homeowner is paying for water to be heated higher than what is necessary while the mixing valve is removing the excess heat after water exists from the hot water heater to the fixture.