How to Set Up Square D Pressure Switches

Written by g.k. bayne
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Square D pressure switches are most commonly found in private home water wells. These spring-loaded and -controlled switches operate the pumps' on and off characteristics. These switches are preset at the factory and never have to be set up or adjusted. In some cases, the water pressure maybe too high or too low for proper operation of the plumbing system. There are two spring adjustments under the plastic cover of the switch. The larger spring nut combination controls the "cut in" and "cut off" pressure, while the smaller spring nut raises or lowers the "cut off" pressure.

Skill level:

Things you need

  • Pressure gauge (optional)
  • Teflon tape (optional)
  • ½ -inch end wrench
  • 7/16-inch end wrench

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  1. 1

    Install a water pressure gauge in a location that can be seen while adjusting the pressure switch. This step is optional if your water system does not have a gauge already installed. Typically a pressure gauge is already installed into the plumbing system near the pressure switch. Most water pressure tanks have a small female threaded orifice for the pressure gauge. Place a couple of rounds of the Teflon tape over the male threads of the gauge. Use the ½-inch end wrench to tighten the gauge into the pressure tank's female threads. You may have to drain the water system prior to a pressure gauge installation.

  2. 2

    Adjust the larger spring nut combination using the ½-inch end wrench. Turn the nut in a clockwise direction to raise the factory presetting range. Rotate the wrench in a counterclockwise direction to lower the overall pressure range. Typically the factory setting is a 20-psi cut-in pressure and a 40-psi cut-off pressure.

  3. 3

    Use the 7/16-inch end wrench to adjust the smaller spring nut combination. Turn the nut in a clockwise direction to raise the cut-off pressure. Rotate the smaller spring nut in a counterclockwise direction to lower the cut-off pressure.

  4. 4

    Open a nearby water faucet and allow the water to flow from the valve to observe the pressure gauge and adjust the pressure switch to your own settings. You may have to perform some minor adjustments to get the water pump to fall into the desired pressure range. It is a good practice to keep at least a 20-psi range between the cut-in and cut-off pressures. A lower range may cause the pump to operate on too much of a frequency, which can cause a premature failure of the electrical pump mechanism.

Tips and warnings

  • Never turn the smaller spring nut too far in the clockwise direction. This will raise the pump's overall cut-off pressure, causing the pump to operate constantly. The higher pressures may exceed normal plumbing connection capacities, causing pipes to rupture and the well pump to burn out prematurely.

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