How to Read an AO Smith Pool Motor Label

Written by:  Danny Rhodehamel

When the time comes to replace your pool pump motor the jumble of numbers and ratings on a motor can be overwhelming. This "How to" will guide you through which information is useful in your replacement pump motor search. We also provide tips on essential parts that should be replaced when installing a new pump motor.

Tips & Warnings

Things You'll Need

Step by Step

Step 1
pool pump gasket and o-ring kit, shaft seal

Tools you may need: 1. A cloth and cleaning solution, this is needed to remove any dirt or grime causing your pump motor label to be unreadable 2. A Shaft Seal or GOKIT when replacing your motor. Working seals and gaskets are vital to the health of your pool pump. A malfunctioning shaft seal will cause water from the pump to leak into your electrical motor causing it to fail prematurely. A GOKIT includes the complete set of your pumps gasket's and O-rings, including the shaft seal.

Step 2
a.o. smith motor label

In general there are two main labels on a pool pump; the pump label and pump motor label. Both can be used to determine the correct motor replacement but first we will focus on the motor label as it is the quickest and easiest to search. If your motor label is unreadable, later in the guide we will show you how to backtrack information off your pump to find the correct replacement. Quick Tip: The manufacturer of the pump motor and the pump itself are different companies even if the pump is brand new from the factory. For example, you have purchased a Hayward Super Pump, the wet end of pump where the water is housed is made by Hayward. The motor attached to that pump wet end was likely made by A.O. Smith, Century or Marathon.

Step 3
ao smith motor label model number

An A.O. Smith pump motor label has a lot of different numbers and ratings that can have an appearance of alphabet soup at first glance. Let's narrow down the scope to just the information we will need to search for a new pool pump motor replacement. The list is as follows: Motor Model Number, Horsepower (HP), Service Factor (SF) and Frame (FR)

Step 4
how to read an a.o. smith motor label

When reading an A.O. Smith pump motor label the most pertinent information to aid you in finding a replacement is the "Motor Model Number." With this information alone you could find the exact match. As shown in the picture, an A.O. Smith motor may have two model number formats listed, either one can be used in INYO's pool pump motor search engine.

Step 5
replacing a pool pump motor

The first format is one that follows the line of "UST1102", "ST1102" or "SN1102". The set of letters in the beginning denote the service factor rating of the pump. The "UST-" stands for an uprated motor and "ST-" means it is a full rated. The last four digits show its HP: "-1102" = 1 HP, "-1152" = 1.5 HP, "-1202" = 2 HP and so on. Type complete number (ex. UST1102) into INYO's product search at the upper right-hand portion of our site to find pool pump motor match

Step 6
pool pump motor replacement

The second format of pump model numbers contains a prefix that is most commonly "C48", "C56", "K48" or "K56". This prefix is followed by four to nine letters and numbers which identify the specific motor. Type this entire number into INYO's product search to find the correct pump motor match. An example of this pump model number format: C48L2N134C1

Step 7
replacement pool motor label

If the Motor's model number is unavailable then we will have to use a combination of the pump label information and other available info on the motor label. The information needed off the motor label is the Horsepower (HP), Service Factor (SF) and Frame (FR).

Step 8
where is my pump model number label

In most cases the Pump's manufacture label is located near the outlet port, location may vary depending upon the maker.

Step 9
how to replace a pool pump motor

On the pool pump label there should be two numbers listed, the serial and model. The pump model number can be entered into our product search engine; the result should provide the make, model and horsepower. Copy down this information and enter our pump motors section by selecting it in our “Shop by Category” sidebar.

Step 10
how do I read my pool pump motor label

In the Pump Motors section you will be asked for the manufacturer then the model. Your specific model may have two categories that list by your pump motor's service factor (SF). The motor's SF is listed on the label, this number will be in the range of 1.00 - 1.95. A SF of 1.00 to 1.27 is listed as an Up rated, anything over is Full rated. Please be sure you match the Service Factor of your pump as failure to do so will cause incompatibility between your current pump and new replacement motor.

Step 11
ao smith motor service factor, frame, horsepower

After checking all the previous information and have found a possible correct replacement, your last piece of info to check will be the Frame (FR). Most motors have a frame of "48Y", "56Y", "48J" or "56J". If your prospective replacement matches HP, SF, and FR then you have successfully found your motor replacement.

Comments (1 to 16 of 16)

Add Comment

User: Inyopools

steve - Some motors show the age of the motor in the serial number on the motor label. The first digit is the plant, the second the month and the next two the year. For example, if your motor's serial # starts with 8A02. it was made in plant 8 in January of 2002. If you don't see similar information in your motor's label, call the manufacturer of the pump and give him the motor or pump serial number.

User: steve

Is there anyway to tell how old a pump is I ,m thinking of buying a previously owned 1 1/2 H.P. super pump.?

User: Inyopools

ac - Motor are designated as round frames or square frames. It relates to the style of mounting plate on the pump housing to which the motor is mounted. See our guide on "How To Replace the Motor on Your Pool Pump" for an example.

User: ac

What does frame mean/indicate???does it signify the face to which pump or device will attach??

User: Inyopools2

Hi Shirl - you would require the B2982 motor located here

User: shirl

my label says Century two speed A.O. Smith Cat--- Serial CA07-25
Part 7-193508-01

User: Inyopools

Donald - You may have an older label or occasionally we will see an off standard label. However, if you type the part number, 7-177803-02, into our general search field, our site will bring up you pump description as a BN50 1 1/2 HP 2 Speed 115V Thru Bolt Motor.

User: Donald

unfortunately my motor label doesn't conform to your description. There's no "model number" listed, hp simply says ---, same for SF ---. It's an A.O. Smith label: there's a reference to a 1081/1563 pump duty, a Cat BN50 and a part number: 7-177803-02. Says HP 1. There's RMP, etc. but none of the label conforms to your description

User: Inyopools

Mike - Here's the link for A.O.Smith motor switches. Try A.O.Smith direct for applicable wiring diagrams.

User: Mike

I need a new switch assembly for ao smith bn82 motor and wiring diagram. Any resources?

User: Inyopools

Age of motor - Give A.O.Smith a call at (937)667-2431. They should have the records to tell you how old your motor is.


with model # C48L2PA105C4 serial # 17908FM how do I determine how old it is?

User: Inyopools

MichaelPA - Almost all single speed pool motors run at the same RPM - 3450.

User: MichaelPA

I have the same RPM's on my 1.5 HP Hayward Pump # SP1515-Z-ES

User: Inyopools

captain scott - Occasionally the manufacturer will designate the motor HP as "SPL". There is no direct correlation between SPL and HP. Sometimes a replacement motor is determined by matching amps or windings but not always. In these cases it's best to call us and we will contact the manufacturer for a match.

User: captain scott

I have an a o smith motor. It's a 3450 rpm, in the hp it has spl. Can anybody tell me the hp?

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Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.