How to Test a Submersible Well Pump: A Comprehensive Guide

Submersible well pumps are essential components of many residential and agricultural water systems, responsible for drawing water from underground sources and delivering it to the desired location. Proper testing and maintenance of these pumps are crucial to ensure reliable and efficient water supply. In this comprehensive guide, we will delve into the step-by-step process of testing a submersible well pump, providing you with the technical knowledge and practical insights to diagnose and troubleshoot any issues that may arise.

Checking the Line Voltage

The first step in testing a submersible well pump is to check the line voltage. This is a crucial step in identifying any power-related issues that may be affecting the pump’s performance. To do this, you will need to remove the cover of the pressure switch and use a multimeter to measure the voltage between the two screws for each leg. This will help you determine if there is any issue with the power supply to the pump.

It is important to note that the line voltage should be within the manufacturer’s specified range, typically between 230-240 volts for a single-phase system or 460-480 volts for a three-phase system. Any significant deviation from these values could indicate a problem with the power source, wiring, or the pump’s electrical components.

Measuring the Current

The next step in testing a submersible well pump is to measure the current. This can be done by disconnecting a black wire from the pressure switch and connecting one lead of your multimeter to the black wire and the other to where it was connected to the pressure switch. Once you have made the connections, turn the power to the pump back on and measure the current.

For a 2-wire pump, you should expect to see a constant current of around 5 amps. Any significant deviation from this value could indicate a problem with the impeller, bearing, line blockage, or the check valve. It is important to compare the measured current to the pump’s rated current, which can be found in the manufacturer’s specifications.

Checking the Check Valve

If your submersible well pump is equipped with a check valve, it is essential to ensure that it is functioning properly. A malfunctioning check valve can cause water to drain through the impeller, causing it to spin in reverse while the pump is off, which can lead to overheating and eventual failure.

To check the check valve, you can use a multimeter to measure the resistance across the valve. The resistance should be low when the valve is open and high when the valve is closed. If the resistance is consistently high or low, it may indicate a problem with the check valve, and it should be replaced.

Testing the Motor Leads

The final step in testing a submersible well pump is to check the continuity of the motor leads. This can be done using a multimeter to measure the resistance between the different leads of the motor.

For a typical 2-wire submersible well pump motor, you should expect to see the following resistance values:

• 5 ohms across the Black and Yellow (main and common) leads
• 18 ohms across the Yellow and Red (common and start) leads
• 23 ohms across the Black and Red leads

These values can vary depending on the manufacturer and model of the pump, so it is important to consult the technical specifications provided by the manufacturer to ensure accurate testing.

In addition to testing the motor leads, it is also important to ensure that the pump is properly grounded to prevent any electrical hazards. You can test for a ground by using a multimeter to check for resistance between any lead and a ground, such as the side shell of a steel casing or the side shell of the motor.

Troubleshooting Common Issues

If the testing reveals any issues with the submersible well pump, it is important to troubleshoot the problem and take the necessary steps to resolve it. Some common issues that may arise and their potential causes include:

1. Low or Fluctuating Water Pressure: This could be caused by a problem with the impeller, a blocked intake screen, a malfunctioning check valve, or a worn-out motor.
2. Pump Cycling On and Off Frequently: This could be due to a problem with the pressure switch, a leaking system, or a malfunctioning check valve.
3. Pump Not Starting: This could be caused by a power supply issue, a problem with the motor, or a faulty pressure switch.
4. Pump Running but Not Delivering Water: This could be due to a blocked intake screen, a problem with the check valve, or a issue with the impeller or motor.

By understanding the common issues and their potential causes, you can more effectively diagnose and address any problems with your submersible well pump.

Conclusion

Testing a submersible well pump is a critical task to ensure the reliable and efficient operation of your water system. By following the steps outlined in this comprehensive guide, you can effectively diagnose and troubleshoot any issues with your pump, ensuring that it continues to provide the water you need for your home or business.

Remember, it is always important to consult the manufacturer’s specifications and safety guidelines when working with electrical equipment, and to seek the assistance of a professional if you are unsure or uncomfortable with any aspect of the testing process.

References

1. Testing a submersible well pump – DoItYourself.com
2. Diagnose and Replace a Submersible Well Pump – Instructables
3. Measuring Well Performance – WaterWorld Magazine
4. Multi-Meter Testing of Submersible Pump Motors – YouTube