A Basic Guide to Understanding Pool Pump Motors

When replacing your pump motor, it’s important to know what motor will work best with your pool. Taking the time to find the right pump motor will extend the life of your pool pump, saving you time and money.
Pool pump motors are located on the ‘dry end’ of the pump and convert electrical energy into mechanical energy. A motor’s main purpose is to power the pump’s impeller, which is the device that moves the pool water into and through the pump.  A properly sized and well-maintained motor can last for 8-10 years. Conversely, poor conditions can cause a motor to fail after one year. Understanding some basic information about pool pump motors will help to extend its life and optimize performance.
What type of motor is a swimming pool pump motor?
Pool pump motors are classified as open drip proof, which means they’re open motors for which ventilation openings are designed so that water cannot enter either directly or by striking and then running into the motor. This is important for two reasons: first is the motor’s obvious exposure to water and second is that proper ventilation is essential to the motor’s function.
Single vs. dual speed motors
A single speed motor runs at the same speed all the time. A dual speed motor has two settings: low and high. The low setting is best for basic pool circulation while the high speed setting is great for use while vacuuming or operating water features. Because there is the option to ramp up the speed on demand, these pumps use less energy, extend the life of the motor, and save money on electricity bills.
Pool Pump Motor LabelWhat do I need to know about my motor and where can I find it?Every motor has a sticker or nameplate affixed to its surface that provides important specifications, including: voltage, (1) horsepower, Hertz rating and (2) service factor. All of this information will be required when the pump or motor is serviced or replaced.The Service Factor is a measure of the capacity at which a motor can operate without overload or damage.

A motor’s effective horsepower, or total horsepower, is the actual power output of the motor. You can determine this by using the nameplate to multiply the horsepower and the service factor together. In this case:

A motor’s effective horsepower, or total horsepower, is the actual power output of the moto
r. You can determine this by using the nameplate to multiply the horsepower and the service factor together. In this case:

1.5 (Horsepower) x 1.3 (Service Factor) = 1.95 (Total Horsepower)
Can I upgrade my pool motor from a single speed to a dual speed?
This is one of the most common questions we hear, especially since dual speed motors are much more energy efficient than single speed. Motors and pumps need to be appropriately matched to one another to perform properly. To ensure that this is done properly, you need to make sure that the total horsepower (horsepower x service factor) of the new motor is greater than or equal to the total horsepower of the original motor.
What is the difference between Full Rated and Up Rated Pump Motors?
All motors are labeled either Full Rated or Up Rated.  Motor manufacturers began up-rating motors in response to consumer perception that higher horsepower means greater efficiency. In reality, up-rated motors are relabeled with a higher horsepower rating and proportionally lower service factor rating. While the horsepower rating is higher, there is not an increase in the motor’s power output.
My label is illegible. Now what?
Unfortunately, due to exposure to the elements, these helpful labels will most likely be useless after a year or two. If this is the case and you need to know the specs of your motor, we recommend referring to your owner’s manual.  If you’re like most people and your manual has half the life of your motor, you’ll need to determine the motor’s frame. The frame identifies the mounting and shaft configuration.  How a motor is mounted to the pump will tell you what kind of frame you have. There are five types of frames:
Pool Pump Motor Line
Thru-Bolt Frame:
The motor mounting bolts are the key with this style of motor. A thru-bolt motor frame fastens to the pump with bolts that pass through the motor. Thru-bolt frames are popular on spas and above-ground swimming pool pumps. Sometimes these motors are also labeled 48Y frames, but they are not to be confused with square flange 48Y frames.
C-Face Keyed Frame:
A keyed frame is characterized by a shaft with grooves along its length that small metal keys slide into. The keyed shaft may also have an internal tapped thread to help hold the impeller once it slides over the key-way. They are also referred to as 56C frames. These pumps are rare in today’s market.
C-Face Threaded Frame:
A threaded frame means that the face of the motor mounts onto the body of the pump and that the impeller is threaded onto the motor shaft. These are also referred to as a 56J frames. Additionally, the impeller may be secured with a small screw, which is threaded into the center of the motor shaft. If the outside of the shaft is not threaded, it is possible the motor is actually a keyed frame, not a threaded frame.
Square Flange:
The square is the most common type of frame. The motor will have a square flange attached to it and not the pump. There are mounting holes located in the corners of the flange. These are also referred to as 56Y and 48Y frames. Some 48Y frame motors are actually thru-bolt style; therefore, check the mounting bolts to make certain they are not thru-bolt style as described below.
Note: Be sure that the square flange is part of the motor and not the pump. If you are uncertain, remove the motor from the pump.
Pumps: Size Matters
A pump that is too large for your pool will force a large amount of water through a filter that is too small, resulting in strain and resistance that will cause the pump motor to wear down and die prematurely. It is always a good idea to operate the pump at the lowest flow rate needed to circulate your pool’s water in 8 hours. It helps to think of it in terms of gas mileage on your vehicle: you get better mileage when you drive at 35 mph as opposed to 80 mph.
Other Dangers to Pump Motors:
  • Heat: Proper ventilation is crucial. A pump motor requires clean, continually circulating air. Generally, motors will run hotter at high altitudes, so we recommend investigating a thermal overload protector, if your motor does not include one.
  • Poor maintenance: If you ever replace your motor, we recommend purchasing a Go-Kit for your pump, which includes a shaft seal, O-rings, gaskets and lubricants. See, the pump and motor have a symbiotic relationship: if one is working well, the other will be healthier and happier for it.
  • Corrosive weather: This includes flooding and hurricanes. In the event of this type of weather, remove your motor and store it inside on a flat surface.
  • Improper installation: Before you turn your motor on, check to see that the line voltage, phase and frequency match the specifications shown on the motor nameplate.