How to Adjust the Differential Setting on a Pump Pressure Switch

Pump pressure switches constantly measure the pressure in a water well holding tank. When the low pressure setting is achieved, the pump contacts touch each other and turn the water well on to draw more water in. When the high pressure setting is achieved, the water well pump turns off. A switch differential is the distance between the low and high pressures that are set or the cut-in and cut-out pressures. Adjusting the differential to a higher number will allow the well to run longer at one time and prevent short-cycling, which uses more energy.

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Pump pressure switches display the pressure of contents in PSI.

Step 1

Insert a screwdriver into each screw in the pump pressure switch cover. Turn each screw counterclockwise to loosen it and pull it straight out of the cover. Pull the cover straight up and off the switch. The cover on pump pressure switches is generally gray in color and a square or rectangular shape with one screw on each side.

Step 2

Observe the pressure switch. There is one large spring with a large nut on top and one small spring with a small nut on top.

Step 3

Place an adjustable wrench on the small nut. Turn the nut clockwise to increase the differential setting and turn the pump off at a higher water pressure.

Step 4

Turn the nut counterclockwise to decrease the differential setting and turn the pump off at a lower water pressure than the current pressure.

Step 5

Turn a garden hose on at the water well or open a faucet in the house. Observe the pressure rating on the gauge when the pump turns on and off. Adjust the nut further to achieve the differential you desire. Release water from the holding tank to check the operation of the pump after each adjustment to see that the well cuts on and off in a cycle.

Step 6

Replace the pump pressure switch cover, insert the two screws and tighten them clockwise with a screwdriver.