To adjust a water pressure switch, you only need a plumber’s pliers to remove the switch cover before turning the adjustment nuts clockwise. Begin by unplugging the pump for safety.
Use your pliers to unfasten the nut that secures the protective cover. Removing the switch cover reveals two springs held down by adjustment nuts.
The nut on top of the large spring adjusts the timing on the cut-in and cut-off pressures. Turn it clockwise to raise the working pressure of the water pump. To control the gap between the cut-in and cut-off, use the small nut. Turn it clockwise to raise the cut-off and tighten the nut. The cut-off pressure should be above the cut-on pressure to prevent the pump from going into a neverending cycle that may damage it.
To get the right pressure, do a bit of tweaking. In order to avoid electrocution, place the cover back on, and secure it in place every time you test your pressure. Once you are satisfied with the adjustment to the pressure switch, put the cover back on, and plug the pump in.
Always ensure that the cut-off and cut-on pressure maintain a set relationship: the cut-off pressure should always be higher than the cut-on pressure.