How to Repair or Replace a Well Pump Pressure Switch

Water Well Pump and Pressure Switch

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Overview
  • Working Time: 45 mins - 1 hr, 15 mins
  • Total Time: 45 mins - 1 hr, 15 mins
  • Skill Level: Intermediate
  • Estimated Cost: $20 to $50

Roughly 34 million homes in the U.S. get their potable water from in-ground wells rather than from a municipal water supply. This can be a matter of necessity, such as in rural areas that aren't serviced by municipal water; or by choice, since some people choose to be independent of municipal water supplies and the water treatment techniques they use. But having your own well comes at a cost—that of maintaining the system. From the foot valve at the bottom of the well to the faucet at the sink, every piece of a well system is your responsibility to keep running efficiently.

When a well pump fails, the issue can often be traced to one part—the pressure switch. This above-ground part located near the pressure tank is responsible for turning the pump on and off by monitoring the pressure in the system. Consisting of an internal spring mechanism linked by electrical contacts, the pressure switch turns on the pump when the system pressure falls to the minimum pressure setting, then turns the system off when the pressure reaches the maximum setting. Operating properly, this switch keeps the home's water supply at a uniform pressure at the taps.

Because it gets so much constant use, the pressure switch is the most common failure point for a well pump. Fortunately, it is also easy to repair and replace.

Before You Begin

Pressure switches typically are available in three pressure ranges: 20 to 40 psi, 30 to 50 psi, and 40 to 60 psi. Make sure to buy a new switch that matches the old one—the rating is usually printed inside the housing of the switch.

Safety Considerations

Electrical power runs through your well pump pressure switch. Before repairing, replacing, or even examining the switch inside its housing, be sure to turn off the power to the pump at the electrical service panel. Once you have removed the switch's outer housing, check again for the presence of electricity with a voltage tester. Also, wear eye protection when working on your well pump pressure switch.

When to Call a Professional

Replacing or servicing the pump pressure switch is usually an easy enough DIY project, but if the pipe fittings or standpipe that holds the pressure switch seem badly corroded or otherwise damaged, it's best to call a well pump specialist to deal with the problem. And if replacing the pressure switch doesn't return the pump to good working order, then the problem lies elsewhere and the system needs the attention of a pro.

What You'll Need

Equipment / Tools

  • Cordless screwgun
  • Wrench set
  • Locking pliers
  • Screwdrivers
  • Non-contact voltage tester
  • Eye protection
  • Shop vacuum
  • Digital camera, or masking tape and pen
  • Air compressor

Materials

  • New well pump pressure gauge (if needed)
  • New pressure gauge (optional)
  • Fine-grit sandpaper
  • Pipe seal tape (Teflon tape)

Instructions

How to Repair a Well Pump Pressure Switch

Given the low cost of new well pump pressure switches and the ease of installation, many owners find it more prudent to entirely replace the switch than to repair it. However, a few simple repairs may keep your well pump pressure switch running longer.

Tip

A pressure switch can sometimes merely be sticky. If lightly rapping on the switch causes the pump to turn on, then it probably just needs disassembly and a good cleaning to return it to good working order.

  1. Clean the Switch

    Because well pumps are often in poorly protected areas subject to the elements, the pressure switch can become clogged with debris, dirt, spiderwebs, insects, cocoons, and mold and mildew.

    After turning off the power, remove the pressure switch's housing. Test for power at the wires using a non-contact voltage tester.

    Thoroughly clean out the switch either with a shop vacuum or by blowing out the debris with an air compressor. If necessary, gently pull out the debris with a soft brush, such as an old toothbrush.

  2. Examine and Clean the Electrical Contact Points

    Double-check to make sure that no power is flowing to the switch. Ensure that the wires are turned clockwise around the screws. Wires, especially stranded wires, are greatly compromised when they are turned counter-clockwise.

    Check the metal contact points that open and close, thus triggering the system off or on, respectively. Fold a small piece of fine-grit sandpaper in half and push it between the contacts to clean burned or pitted contacts.

  3. Check the Stand Pipe

    Check the nipple standpipe on which the pressure switch rests. Unscrew the pressure switch from the nipple pipe and make sure that it is not corroded or clogged with sediment. (You'll need to disconnect the wires to do this.)

How to Replace a Well Pump Pressure Switch

Replacing a pressure switch is not much more difficult that repairing it, so many people faced with switch failure opt to simply buy and install a new switch.

  1. Turn off the Power and Remove the Pressure Switch Housing

    After turning off the power to the pump at the main service panel, use a manual screwdriver or screwgun to loosen the screws that hold the pressure switch housing in place. Lift the housing off the pressure switch mechanism. Test for power using a non-contact voltage tester.

  2. Document the Wiring Configuration

    If you are accustomed to wiring household outlets and ceiling lights, you have the basic know-how to disconnect and reconnect wires on a well pump pressure switch. However, this configuration can be confusing. Assuming that the existing wiring is correct, document its configuration by taking a picture of it or by labeling the wires with masking tape. It is easy to confuse the power supply wires with the pump motor wires since they look similar.

  3. Release the Pressure from the System

    Release the pressure by draining water from the tank. Confirm that the pressure has been released with the system's pressure gauge: It should read 0 PSI.

  4. Remove the Pressure Switch

    With a cordless screw gun or a manual screwdriver, turn out the screws holding the electrical wires to the contact points. Clamp locking pliers on the lower nipple standpipe to keep it from rotating. Then, with a correctly sized wrench, unscrew the pressure switch by rotating it counter-clockwise off the nipple.

  5. Install the New Pressure Switch

    Clean the water pipe's threads of any old pipe sealant or pipe seal tape. Cover the nipple threads with a couple of loops of new pipe seal tape, wrapped in a clockwise direction.

    Next, thread the new pressure switch onto the water pipe—by hand at first, then tightening with a wrench hold holding the standpipe with locking pliers.

  6. Install a New Pressure Gauge (Optional)

    While it is not necessary to replace the pressure gauge when replacing the pressure switch, many DIYers take the opportunity to upgrade the gauge. The gauge is an inexpensive part ($10 to $15) and is simply screwed into the pipe fitting leading to the pressure tank. Wrap the threads of the new gauge with pipe seal tape before threading it into the fitting.

  7. Reconnect the Wires and Replace the Housing

    Clean the tips of the wires with fine-grit sandpaper so that the copper is shiny. Reconnect the wires to their contacts and screw them down tightly.

    Replace the switch housing, then turn on the power to the pump at the main service panel.

  8. Repressurize the Tank

    Using an air compressor, add compressed air to the tank to bring it up to the correct pressure. Often, this is between 2 and 4 PSI below the switch's lowest limit, also called the cut-in limit. For example, for pressure switches rated at 40 to 60 PSI, you would pressurize the tank to 38 PSI. However, be sure to consult the manufacturer's instructions for information specific to your system.