Turn the "High" differential knob, at the bottom of your hot-water tank, to 190 degrees Fahrenheit. This is the highest setting your heater can achieve.
Turn the "Low" differential knob, next to the High knob, to 170 degrees Fahrenheit. This is lowest your heater can go to before it kicks back on.
Set the "DIFF" knob to 15 degrees Farhrenheit. This setting adjusts the temperature difference allowed before the hot and cold water mix in the tank. Put the system into operation and observe the entire cycle at least once to make sure it is functioning properly.
- The difference between High and Low settings must be at least 20 degrees.