Submersible pumps, built to last in tight, corrosive water well environments, can prove nearly inaccessible when suspended 10 feet from the bottom of such a well — often over 300 feet deep. This can make maintenance issues hard to diagnose, as well as leave the equipment susceptible to ambient temperatures, rainfall and drought. A rise in residential housing construction coupled with increasing water scarcity have caused a boom in the submersible well pump market, making the ability to quickly troubleshoot existing pump issues critical in aiding pump longevity.
Common issues that might occur with your submersible pump include:
- The pump motor isn’t running
- Little or no liquid is being delivered by the pump
- Or we have inadequate submergence or foreign matter
We’ll take a look at each of these submersible pump issues and offer potential fixes.
Pump Motor Not Running
When the submersible pump motor isn’t running, we can consider a few different issues.
First, it could be a motor thermal overload protection trip. When the pump draws more current than the motor has capacity for, it causes the motor to trip. Look at these potential causes.
- Incorrect control box: All single-phase three-wire pumps require a control box configured of three wires plus a ground wire. A quick disconnect control box contains a start compactor and a relay, both designed for specific motor model numbers. If you suspect an incorrect control box, compare the voltages and horsepower capabilities of the control box and pump to ensure a match. Many experts recommend using a control box and motor from the same manufacturer.
- Faulty thermal protector: The thermal protector is a small switch that automatically opens to protect the equipment when the motor gets too hot. It closes when the motor cools down. Unfortunately, if you suspect a faulty thermal protector, you have the added challenge of locating the component. For instance, within Goulds Water Technology’s 4-inch submersible pump line, you might find the thermal protector in the motor or the control box, depending on the horsepower. Thermal protectors located in the control box can be tested, replaced and manually reset. Every control box has an ambient temperature limit, so consider the external temperature. Shield the box from potential heat sources, by shading it for example. Allow the motor to cool; this will give the thermal protector time to reset automatically.
Another issue that can cause a submersible pump motor to stop running is inadequate voltage. Most submersible pumps require an external power source to operate and if that source provides inadequate voltage, it can damage the motor. Consider these potential causes of inadequate voltage.
- Power supply issue: Since voltage is related to amperage, it is critical to ensure the supply voltage is within the typical tolerance range of ± 10% of the nameplate voltage of the motor. Using a meter, measure the incoming voltage to determine if there is a power supply issue.
- Wire size: Ensure that the wire from the service entrance to the motor is sized properly. As motor amperage varies across manufacturers, use the wire sizing charts specific to the manufacturer of the motor. Undersized wire leads to a voltage drop at the motor which drives up the amperage.
- Damaged power cable or grounded motor: A short to ground will show up with either a grounded motor or damaged cable. Starting above the well, with the power off and the leads disconnected measure each hot lead to ground using an insulation resistance meter or megger. A bad reading above ground could be due to either the wire or motor. Use the provided chart from the manufacturer to determine the condition of the wire and motor.
A voltage test can typically help this issue as the cause, though some states require a licensed electrician to perform this test.
Pump Delivering Little to No Liquid
When a submersible pump is delivering little or no liquid, consider these potential causes.
- Faulty or incorrectly installed check valve: The check valve allows the flow of water to go one way and not the other. You can detect a backward check valves issue during installation, as there will be no flow. After installation, check valve can sometimes stick partially open, causing flow restriction. Make sure to inspect the check valve and repair as needed.
- 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. This runs the air out until the flow delivers again. To prevent exposing the pump to air, make sure to size the pump properly and employ run-dry protection devices.
- Lift too high for pump: Well conditions can change over time. For instance, a drought can cause the pumping level in the well to increase, which increases the resistance or head. This, in turn, reduces the flow of the pump. We can lower the pressure at the pressure switch to increase the flow, but since most homeowners want good water pressure, we likely need to re-evaluate the well conditions and corresponding pump.
Inadequate Submergence, Foreign Matter
Regardless of what you troubleshooting for, we can often trace poor pump performance and even pump failure to inadequate submergence or blockages from foreign matter. Always inspect for these issues during routine maintenance.
- Inadequate submergence: Environmental factors like draught can mean the pump does not submerge enough to pump water. To check, confirm the correct unit submergence level and lower the pump if possible.
- Foreign matter: If bound by foreign matters such as leaves, dirt or sand, the pump must be pulled, cleaned and adjusted to the correct depth.
Industry professionals spend much of their time responding to and troubleshooting water well issues, from monitoring or servicing wells to diagnosing equipment malfunctions. Knowing how pump equipment functions, what each component installed on the pump equipment is, what those components do, and how they interact are essential in any troubleshooting situation. I recommend hands-on training, like our Goulds Water Technology Factory School, to give industry professionals an understanding of pump system basics and the fundamentals of hydraulic systems.