How to Adjust a Water System Pressure Switch

Written by ian kelly
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How to Adjust a Water System Pressure Switch
Adjust your well water pressure switch to raise or lower you household water pressure. (BananaStock/BananaStock/Getty Images)

Your water pressure switch is designed to keep your home water well system at pressures high enough to satisfy domestic needs and low enough to prevent damage to domestic water heaters and appliances. Although pressures fluctuate with normal use, if supply drops off suddenly, check the entire system for leaks and integrity before adjusting the pressure switch. The unit has two adjustments: one for controlling overall pressure, and the other to control the gap between the cut-in pressure and the cut-out pressure timing. As a general rule, domestic water pressure should not exceed 75 psi.

Skill level:

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Things you need

  • 11/32 nut driver
  • Socket wrench

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  1. 1

    Turn the breaker switch on the main electric panel supplying power to the well water system to the "off" position. Tape the switch to the panel with a piece of masking tape to prevent another household member restoring power while you're working.

  2. 2

    Identify the pressure switch attached to the top of the well water pressure tank. Loosen the domed nut holding the outer cover onto the pressure switch with an 11/32 nut driver. Remove the cover and put it on one side.

  3. 3

    Make a note of the reading on the pressure gauge situated below the pressure switch. Identify the two springs inside the unit. The larger spring controls the maximum amount of pressure inside the pressurised water tank. The smaller spring controls the differential between the points where the low-pressure cut-in switch starts the pump and the high-pressure cut-out switch stops the pump.

  4. 4

    Turn the nut on top of the large spring clockwise with a socket wrench to raise the maximum amount of pressure in the water tank, and counter clockwise to lower the maximum amount of pressure in the water tank.

  5. 5

    Tighten the nut on top of the small spring clockwise with a socket wrench to decrease the differential between highest pressure and lowest pressure, and loosen the nut counterclockwise to increase the differential between highest pressure and lowest pressure. For example, if the pump cycles in at 20 psi and cycles out at 50 psi, there is a 30-psi differential or "gap" between the upper and lower pressures.

  6. 6

    Replace the pressure switch cover and tighten the dome nut securely. Turn the breaker switch back on and start the pump. Monitor the water pressure gauge on the pressure tank to ensure that the system is operating properly.

Tips and warnings

  • If you tighten the nut on the small spring too much, the pump will either "short cycle" by kicking in and out repetitively, or it will run continuously until it burns out. A short cycling system consumes more power and leads to premature pump failure. On the other hand, if you loosen the nut too far, the system won't operate with enough at the bottom of the cycle for you to take a decent shower or to run certain home appliances.
  • Don't increase your pressure too much by tightening the nut on the large spring; 50 to 55 psi works fine for most people. Although pressure over 75 psi will fill your bathtub quicker, it may damage appliance water valves and cause dripping faucets.

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