Step 4 · Adjusting the Pressure Switch

The pressure switch has adjustment screws that control springs. Turning the large adjustment screw affects both the cut-in and cut-out pressures. Turning it clockwise increases pressure, and counter-clockwise decreases it. The small adjustment screw fine-tunes the difference between cut-in and cut-out (the differential). Adjust incrementally, no more than 2 PSI at a time, and allow the system to cycle to observe the effect. For example, to raise the cut-out pressure by 2 PSI, turn the large screw clockwise approximately one-quarter turn. Then, turn on a faucet to let the pressure drop and observe the new cut-in pressure.