Submersible pumps are prized for their reliability, but they can still occasionally suffer from serious problems, especially if your well is poorly maintained. Dry running is one of the most serious faults that can affect submersible well pumps, and it can cause catastrophic damage to your pump's motor.
How Does Dry Running Damage Submersible Well Pump Motors?
Submersible pumps are so-called because they are installed beneath the water inside your well, unlike surface-mounted jet pumps. Because they are constantly submerged, the well water acts as both coolant and lubricant, preventing excessive friction and overheating that can damage your pump.
If your submersible pump runs while it is not completely surrounded and filled with well water, this cooling and lubricating effect is lost. Dry running can severely damage many of the pump's components, and motors are especially vulnerable.
Without effective lubrication, the motor will have to work harder to counteract the increased friction generated by impeller bearings and other moving components. This can cause rapid motor overheating, which is made worse by the lack of water to effectively dissipate heat.
In a best case scenario, the pump's thermal sensor will automatically shut off the pump before the motor suffers any serious damage. This saves the pump, but leaves the well unusable. If the pump's thermal sensor does not function properly, the pump motor may run dry for some time. The motor will eventually burn out, and will need to be completely replaced.
Why Is My Submersible Well Pump Running Dry?
During long periods of hot, dry weather, the water level in your well may drop naturally, leaving the pump literally high and dry. The pump is fitted with float switches, which automatically shut off power if water drops below a safe level. If these float switches are faulty due to damage or poor maintenance, the pump may start to run dry.
Your well may also have low water levels because of problems with the well screens. These screens surround the perimeter of the well, and allow groundwater to enter the well while keeping solid debris out. If they become clogged with debris, or are damaged by shifting soils or ground tremors, they may block groundwater from entering the well.
Pumps can also run dry even when they are properly submerged. If there are faults with the pump's suction line, impeller, or electrical control board, the pump's motor may run without effectively drawing water into the pump itself.
How Can I Tell If My Pump Is Running Dry?
If your pump deactivates itself a few seconds after being switched on, its thermal sensors or float switches may be triggered by low water levels. This may be expected during periods of drought, but if you are not expecting lower water levels in your well, the pump or the well itself may be suffering from serious issues.
If the sensors or float switches have failed and the pump continues to run dry, you must deactivate it quickly to prevent severe motor damage. Check to see if any water is actually making it to the surface, and listen to unusual noises coming from the well -- submersible pumps are usually very quiet, but can make loud rattling or rumbling noises when running dry.
If you suspect your submersible well pump has been running for any significant amount of time, you should call in a professional well pump repair service as soon as possible. These services will inspect the pump's motor for signs of dry running damage, and repair or replace it as necessary. They will also check and repair other components vulnerable to dry running, such as the impellers and seals.