Pool Pump Motors

The heart of the pool pump is indeed the motor which is responsible for all of the circulation in your pool. Circulation of water is essential for pool filtration; without it, all you would have is a green pond in your backyard. If your motor has ever abruptly gone out, you know how urgent its replacement is. This is why we recommend keeping your pool pump owners manual in an accessible place and making sure you note the make and model of your pump before the outside elements fade the label on the pump.

Which Replacement Motor Do I Need?
The best way to determine the proper replacement motor is by having the pump manufacturer's name and model number. By “pump”, we mean the complete unit which is comprised of the wet end (where the strainer basket is) and the motor. Regardless of the pump you have – Hayward, Pentair, Sta-Rite, Jandy, etc. - the motor is made by a third party manufacturer and the same motor is used on multiple pumps. There is no such thing as an A.O. Smith or Magnetek pump – these companies only make the pool pump motors. Since replacement pool pump motors are listed according to the complete pump model, having only the model number from the motor makes it much more difficult to cross-reference. Look instead for a label or plate on the basket portion of the pump and see if you can get the model number for the whole unit, such as “Hayward Super Pump SP2605X7”. With this information, it is usually fairly simple to look up the proper replacement. If you cannot locate the pump model name or number, check for a part number on the strainer basket lid. This will usually be molded into the plastic and can often be used as a cross-reference to figure out which pump you have.

The pool pump motors we carry are made by A.O. Smith, one of the leading motor manufacturers. You might also see Centurion or Magnetek as a brand name; these are also made by the parent company A.O. Smith. You can replace another brand, such as Franklin or GE, with an A.O. Smith motor. You will simply need to match up the specifications which would include the horsepower, service factor, voltage, amps, frame type, RPM and whether the motor is single or dual speed. Again, the easiest way to do this is to first figure out the exact complete pump you have.

Full Rate vs. Up Rate pool pump motors

This is one of the most confusing aspects of pool pump motors. To understand it, you first need to know that the effective horsepower of a pump is determined by the horsepower (HP) and the service factor (SF). When these two numbers are multiplied, you get the effective horsepower – in other words the actual power output of the motor. So for example, if you have a 1 HP motor with a 1.25 SF, you would multiply 1 x 1.25 to get an effective HP of 1.25.

Since pool owners tend to think higher horsepower is always better, manufacturers have taken to “uprating” pool pump motors. They will relabel a .75 HP motor with the next size up, 1 HP, and then simply lower the service factor. So the same motor can be labeled two ways – as a “full rate” .75 HP motor with a service factor of 1.65 or as a 1 HP “uprated” (also called “max rated”) motor with a service factor of 1.25. The effective HP for both of these is exactly the same but the pool owner feels better because they just got a 1 HP motor which appears to them to be more powerful. It is essentially a marketing tactic based on consumer demand. Even though a .50 HP pump may be plenty powerful for a particular application, most pool owners want to oversize their pumps. In reality, it is best to size your pump properly for maximum efficiency. Pay more attention to the volume of water in your pool, the feet of head (which is determined by the length of plumbing that runs between the pump and the main drain), and how many gallons per minute you need to circulate the entire pool within eight hours. This information will best determine the horsepower you need.

Single vs. Dual Speed pool pump motors
Most pool pumps currently in operation are single speed pumps which run at one speed at all times. In response to growing energy costs and environmental concerns, manufacturers have begun making dual speed pool pumps which have both a low and high speed setting. These two settings allow you to run the pump at a lower speed for basic pool circulation and then switch to the high speed setting only when additional power is needed. The higher speed is appropriate for water features, backwashing a filter, vacuuming the pool or any other application that requires more power. Dual speed pumps offer significant energy savings and are now required by law in some areas, the entire state of California being one of them. Another advantage is that the low speed setting of a dual speed pump operates more quietly than a single speed pump. When replacing a pump motor, be sure to check whether you have a single or dual speed pump because the pool pump motors will be different.

Here is a sample scenario that shows the savings of using a dual speed pump. Let's say we have a 25,000 gallon pool using a single speed 1.5 HP pool pump. It runs 8 hours per day and pumps about 80 gallons per minute, which means that it circulates 38,400 gallons daily. The pump draws 9.0 amps at 240 volts. At a cost of 10 cents per kilowatt hour, that translates to a cost of $1.73 per day or $51.90 per month to operate the pool.

The same 25,000 gallon pool with a two speed 1.5 HP pool pump runs 12 hours per day at low speed. At the lower speed it pumps about 40 gallons per minute which means that it circulates 28,800 gallons each day. The pump draws 2.25 amps at 240 volts at low speed. At a cost of 10 cents per kilowatt hour, that translates to a cost of $0.65 per day or $19.50 per month to operate the pool.

Can I Replace My Single Speed Motor with a Dual Speed?
You can exchange a single speed motor for a dual speed as long as you make sure the high speeds match. This way, the impeller on your existing pump will match work with the replacement motor. So for example, if you have a 1 HP Hayward Super Pump single speed model, you would choose the replacement motor for a 1 HP Hayward Super Pump dual speed. The high speed setting on this pump will be the same speed as the single speed model.

Another consideration is that you'll need a way to switch between the low and high settings. Replacement pool pump motors typically do not include a switch. The simplest option is a switch that attaches to the end cap of the motor (part # 615332) . You can also wire your pump to a dual speed control that would be mounted on a post near your pool equipment. If you already have a timer to turn your pump on and off, you can select a dual speed pump timer which will provide only one function, switching from high to low speed (part # T106R). There are also combination units that will provide both an on/off switch and a high/low switch (part # T10604R). If you already have or are considering a more elaborate automated control system such as the Jandy Aqualink, you would need a dual speed pump relay which is usually sold separately.

Can I Replace My Current Motor with a Higher or Lower Horsepower?
The answer is yes but you will also need to replace any parts that are specific to the horsepower of the motor. These will usually be the impeller and diffuser. It is very important to have the parts matched to the motor. If you go higher, say from a 1 HP to a 2 HP, and do not change any parts, you will not get any of the benefits of the greater horsepower. This is because the 1 HP impeller will only be able to move a 1 HP pump motor. On the other hand, if you go from a 2 HP to a 1 HP, the motor will burn out as a result of the 2 HP impeller trying to turn too quickly.

How Long Should a Motor Last?
There are a few variables that affect the answer to this question. In a perfect world with a properly sized and maintained pump and filter system, a pump motor should run for years without a problem. However pumps are often oversized which means that strain on the motor is common. As an oversized pump tries to force water through an undersized filter, there is resistance that will eventually burn the motor out. Other factors that shorten the life of a motor will be poor or no maintenance, corrosive weather conditions, or improper installation. We have had some customers who have burnt out a motor in less than a year and others who call because they finally need a replacement motor after more than a decade of pump use. Much will depend on the proper sizing and care of your pump and filter. The typical manufacturer's warranty on replacement pool pump motors is one year.

Why Should I Replace the Shaft Seal?
If you are going to replace your pool pump motor, we highly recommend replacing at least the shaft seal. Using an old seal with a new motor is like asking for a leak. The old seal will likely be worn and will not match up to the new motor. Since shaft seals are typically around $15.00 – 20.00, a better value is a Go-Kit which includes the shaft seal and all O-rings, gaskets and lubricant for your pump. These prepackaged kits are specific to the brand and model of pump and cost about $35.00. A Go-Kit will ensure that all of the key parts are new when you replace the motor.

Visit our Pool Pump Motors store.