Submersible well pumps are an essential component of many residential and commercial water systems. However, like any mechanical device, they can encounter problems that require troubleshooting. This guide provides a detailed overview of submersible well pump troubleshooting, focusing on measurable, quantifiable data to help you diagnose and resolve issues effectively.
1. Inadequate Submergence or Foreign Matter
Inadequate submergence and foreign matter are common issues that can significantly impact pump performance. To troubleshoot these problems, follow these steps:
Inadequate Submergence
Environmental factors, such as drought, can lead to insufficient submergence. Measure the correct unit submergence level and, if possible, lower the pump to ensure adequate water levels. The recommended submergence level for a submersible well pump is typically 10-20 feet below the static water level, depending on the pump’s size and the well’s depth. Insufficient submergence can cause the pump to run dry, leading to overheating and potential damage.
Foreign Matter
Inspect the pump for blockages caused by leaves, dirt, sand, or other debris. If foreign matter is present, pull the pump, clean it, and adjust it to the correct depth. The intake screen should be free of any obstructions, and the well should be periodically cleaned to remove accumulated sediment. Blockages can restrict water flow, reducing the pump’s efficiency and causing it to work harder, potentially leading to premature failure.
2. Electrical Issues
Electrical problems can also affect submersible well pumps. Common electrical issues include:
Wire Size
Ensure that the wire from the service entrance to the motor is properly sized. Use the manufacturer’s wire sizing charts to determine the appropriate wire size based on the motor’s amperage. Undersized wire can lead to a voltage drop, increasing amperage and potentially damaging the motor. For example, a 1 HP submersible well pump typically requires a minimum of 12 AWG wire, while a 5 HP pump may require 8 AWG or larger.
Damaged Power Cable or Grounded Motor
A short to ground can be caused by a damaged cable or a grounded motor. Measure each hot lead to ground using an insulation resistance meter or megger to identify the source of the problem. A bad reading could indicate a problem with the wire or the motor. Consult the manufacturer’s voltage test guidelines, and in some states, a licensed electrician may be required to perform this test. The acceptable insulation resistance value is typically 1 megohm or higher.
3. Pump Delivering Little to No Liquid
When a submersible pump delivers little or no liquid, consider these potential causes:
Faulty or Incorrectly Installed Check Valve
The check valve allows water to flow in one direction and prevents backflow. A backward check valve can be detected during installation, while a partially open check valve can cause flow restriction after installation. Inspect and repair the check valve as needed. The check valve should be installed with the flow arrow pointing in the correct direction, and the valve should fully open and close when tested.
Pump Air-Bound
Excess air can cause performance issues and potentially damage the pump. To potentially fix an air-bound pump, successively start and stop the pump to run out the air until the flow delivers again. Proper sizing and run-dry protection devices can help prevent air exposure. The pump should be able to deliver its rated flow and pressure without any air bubbles or cavitation.
Lift Too High for Pump
Well conditions can change over time, causing the pumping level to increase and reducing the flow of the pump. Lowering the pressure at the pressure switch can increase the flow, but re-evaluating the well conditions and corresponding pump may be necessary. The pump’s maximum lift capacity should be matched to the well’s depth and water table level to ensure optimal performance.
4. Pump Motor Not Running
If the submersible pump motor isn’t running, consider these potential issues:
Power Supply
Check the power supply to ensure it is properly connected and functioning. Verify that the voltage at the control box or pump motor terminals matches the pump’s rated voltage, typically 230V or 460V for larger pumps.
Overload Protection
Examine the circuit breaker and fuses to ensure they are not tripped or blown. The overload protection should be sized according to the pump motor’s full-load amperage (FLA) rating, which can be found on the pump’s nameplate or in the manufacturer’s specifications.
Motor Windings
Inspect the motor windings for continuity and resistance using an ohm meter. Consult the manufacturer’s specifications for the appropriate values. A reading of zero ohms or an open circuit indicates a winding failure, and the motor will need to be replaced.
Start Capacitor
Test the start capacitor for proper capacitance using a capacitance meter. Replace the capacitor if it fails the test. The start capacitor’s value should match the manufacturer’s recommendation, typically ranging from 200 to 600 microfarads (μF) for submersible well pumps.
5. Control Box and Pressure Switch
Inspect the control box and pressure switch for proper functionality:
Control Box
Ensure the control box is receiving the correct voltage and that the contacts are clean and functioning properly. The control box should provide the necessary protection and control functions, such as overload, short-circuit, and voltage monitoring.
Pressure Switch
Check the pressure switch for proper operation and adjust the pressure settings as needed. The pressure switch should be set to the manufacturer’s recommended range, typically between 30-50 PSI for residential applications and 50-100 PSI for commercial or industrial use.
6. Drop Pipe and Intake Screen
Examine the drop pipe and intake screen for leaks and blockages:
Drop Pipe
Inspect the drop pipe for leaks and replace the damaged section if necessary. Leaks in the drop pipe can cause a loss of water pressure and flow, reducing the pump’s efficiency.
Intake Screen
Clean the intake screen to remove any mud or sand blockages. A clogged intake screen can restrict water flow, causing the pump to work harder and potentially leading to premature failure.
7. Worn Parts
Inspect the pump for worn parts, such as the impeller, casing, or other components. Replace any damaged parts as necessary. Over time, the pump’s internal components can become worn or damaged, reducing its performance and efficiency.
By following these comprehensive troubleshooting steps and using the provided data points and measurements, you can effectively diagnose and resolve issues with your submersible well pump. Remember to always prioritize safety and, if necessary, consult a licensed professional for assistance.
References:
– Submersible Well Pumps: Tips for Servicing & Troubleshooting
– Submersible Pumps Troubleshooting
– Submersible Well Pump Troubleshooting
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