The pump is the “heart” of the pool system, pumping the water to and through the entire system.
Most pool pumps are either self-priming or flooded suction centrifugal pumps. Smaller commercial operations — motel or condominium pools, for example — generally use self-priming pumps. Larger pools typically include flooded suction pumps.
The two differ in that self-priming models are designed to run above pool-water level, and flooded suction are installed below the water level. Also, self-priming pumps have an integral strainer pot (also called a trap, leaf trap, or hair and lint pot) and flooded suction pumps need a separate strainer pot.
Pumps generally use one of two types of motors: Open frame — which includes openings for ventilation — and closed. Smaller, self-priming pumps mostly run off open-frame motors. These are less expensive, but tend to collect dirt, hair and other refuse. This reduces airflow, resulting in a hotter-running motor that will not last as long. However, open-frame motors are generally rated “drip proof,” meaning a little water dripping on one won’t ruin it.
In contrast, larger pumps tend to use more expensive, totally enclosed, fan-cooled (TEFC) motors, which are protected from dirt, moisture, rodents and such.
Pump motors also differ electrically. Smaller facilities usually rely on single-phase while larger facilities often have three-phase power available. The flooded suction pumps typically found on these pools have three-phase motors. Three-phase motors are more efficient and can use up to one-third less electricity than single-phase motors of the same horsepower. They can also be connected to an energy-saving variable-frequency drive to reduce the motor speed during off-peak hours. VFDs have been around for a while, but because of their cost, it has not been economical to use them on smaller motors until recently.
The primary maintenance task with any pump is cleaning the strainer basket. Depending on bather load and other factors, it may need cleaning anywhere from several times a week to once a month. Operators should determine their specific needs individually, and cracked or broken baskets should be replaced immediately. Keeping one or more extra baskets on hand is recommended. It can reduce pump downtime and provide more flexibility in scheduling cleaning.
If hair or other debris passes through the strainer basket, cleaning the impeller also may be required periodically. When debris gets caught in the impeller it reduces the water flow and if it’s not addressed, eventually it may prevent the pump from starting. Cleaning it may be as simple as pulling a hairball out with a finger (It goes without saying, but be sure the pump is off!) or it may require opening the pump.
Maintaining the electrical supply is another important, but often-overlooked task. Regularly check contactors, overloads, fuses and time clocks for loose wire connections or signs of overheating.
Good maintenance also requires attention to sanitation. Floors should always be clean to prevent debris from getting into the pump motor. This is especially important with open frame motors. Use compressed air to occasionally blow the dust out of the motor. Additionally, with flooded suction pumps located in a pit, prevent flooding by making sure screens are clear and drain lines are free-flowing. If there is a sump pump, periodically clean the sump and test the pump. Consider installing a flood alarm so someone is alerted to rising water around that pricey pool pump.
If your system isn’t diligently maintained you’ll be able to spot problems using your senses. For example, if you see smoke and smell burning electrical, you know it’s time to order a motor.
Some common problems with pumps include failure to start, low flow and leaks. Failure to start can result from several different causes, most electrical. It could be a circuit breaker, fuse, contactor, time clock or overload, or it may be the result of a motor problem causing another failure.
Single-phase pumps also can fail to start because of a bad capacitor or start switch. Generally, if a capacitor looks bad, it is. If it looks OK, substitute a good capacitor and if the motor works, it was clearly the capacitor. Keeping a spare capacitor or two for testing is well worth the expense.
Leaks should be addressed immediately. If the pump shaft seal starts to leak, it needs to be replaced. Otherwise, water will likely get into the motor bearing, which will start making an unusual, high-pitched whine as it fails. Besides the shaft seal, there can be leaks from seal plate O-rings, case gaskets, plumbing connections and the body of the pump.
Similarly, DE can ruin the motor bearings if it is allowed to collect on the floor and gets blown through the motor. To help troubleshoot, be sure that your pump system includes pressure and vacuum gauges, flow meters, volt-ohm meters, clamp-on amp meters and/or infrared thermometers. These should be checked daily. High pressure, low vacuum and low flow, generally mean a dirty filter or a closed valve on the pressure side. Low pressure, low vacuum and low flow may mean a clogged leaf basket or a jammed or worn-out impeller. Low pressure, high vacuum and low flow could be a closed suction-side valve, or maybe a towel stuck in the suction plumbing or other intake obstruction. Decreasing flow over a period of time might mean a failing impeller; they don’t usually suddenly wear out. This is why it’s important to take readings when everything is working.
Generally, a heavy-duty flooded suction pump or solid brass self-priming pump will outlast a plastic pump, and a more expensive pump will outlast a cheap one. Many technicians say a motor on a typical pool pump (single-phase, self-priming) in a commercial application will last 2.5 to five years, but with a commitment to optimal maintenance they can last longer.
When deciding whether to repair or replace a pump or motor, several factors can affect the decision. If the cost to repair exceeds half the cost to replace, it’s often best in the long run to replace; however, if the replacement motor is more energy-efficient than the old one, also calculate the cost savings in electricity over five or 10 years. Energy and cost savings can make it smarter to replace. Also note that some newer self-priming pumps are so much more efficient that it’s often possible to replace an old pump with a lower horsepower rated model. Finally, when possible always consider multiple pumps. When a single pump goes down there's no backup system and the entire pool has to be closed. Second, because pool pumps usually run 24 hours/day, full capacity is not always needed. With circulation systems including multiple pumps, one can be turned off to save electricity during off-peak usage.