How to Connect a Water Pump Pressure Switch

Written by john landers | 13/05/2017
How to Connect a Water Pump Pressure Switch
Many older homes have wells that require a new water pump pressure switch. (Comstock Images/Comstock/Getty Images)

A water pump pressure switch allows for control of an electricity-driven water pump. The water pump monitors the water level for pumping systems, including jet, submersible and reciprocating pumps. The switch automatically starts or stops the pump at different preset pressures. For example, a well has a pump that draws water from the well and pressurises the pipes leading to the home. The pump sends water to the well tank, which compresses the air. The system maintains the pressure to provide water when the pump stops running.

Find out the local building code requirements for installing a water pump pressure switch -- go online or make a trip to the local building inspection department. Some building codes may require licensed professionals complete part or all of the work.

Determine the type of pressure switch for the pumping device. Select between an electromechanical switch and an electric/solid state device. An electromechanical has a low cut- feature that shuts the unit down when it senses low water levels. The electric/solid state switch requires a button to adjust the pressure and have certain diagnostic capabilities for troubleshooting.

Find out the "cut-in" (low number) and "cut-out" (high number) pressure numbers for the pump. Record the tank precharge pressure and the pressure connection size. The standard size is 1/4-inch national pipe thread (NPT) or 3/8-inch NPT.

Go to the circuit breaker panel or fuse box and turn off the power to the pump. Open a valve to release water from the tank and take off water pressure. This works for systems where the pressure switch is located on top of a tank or well pump. Connect a hose to the tank to drain water to the exterior of the building.

Touch the probes of an electrical voltage tester to the terminals on the old switch to ensure the power is off. Disconnect the wires from the old water pump switch. Mark each wire and the terminal it connect to with a piece of masking tape. This helps when wiring the new switch.

Disconnect the old control. Install the plug in the opening to plug the late. Assemble the new switch. Use pipe compound on the threaded connections. Connect the wires to the switch. Usually, the 120-volt circuit has four wires. Connect the two wires electrical distribution panel -- hot and neutral or "line in" wires, to the terminals on the switch marked "Line." The "line out" hot and neutral wires transmit power from the switch to the pump.

Follow the manufacturer instructions for testing the switch. Closed any faucet or drains opened earlier. Turn the power on to the switch. Monitor the switch; shut the power off when the reading reaches about 9.07 Kilogram per square inch. Examine the system for leaks. Dry the water from around connection that leak. Inspect the connections to identify the leak, including around the pump, mounting pipes and fittings. Disconnect the part and reapply pipe compound on the connections.

Things you need

  • Voltage tester
  • Masking tape
  • Switch
  • Riser
  • Pipe plug
  • Pipe dope

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