How to Read a Pool Motor Label

WRITTEN BY:  Inyo Pools

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This "How To" will provide an explanation on the stats and ratings listed on a pool pump motor label. When attempting to find a replace a pool motor not all of these ratings are necessary but it is good to know, just in case.


Step by Step


Step 1

The model number is the easiest way to identify your pump motor replacement. Manufacturers like A.O. Smith do not have a set format for their model numbers. This is dependent upon the specific pump the motor is to be matched with. For example, an A.O. Smith motor that is compatible with Pentair brand pumps may have a model number of B853 or BN24, but an A.O. motor meant for a Hayward pump will have a model number of UST1102 or ST1152. On the motor label there may be a second model number listed, this number generally will begin with either a "C48", "C56", "K48" or "K56" followed by four to nine letters and numbers. An example of this style is C48L2N103B1. Not all manufacturers call their model number by that name, Century Electric refer to theirs as a “Part Number” which has its own unique format. A Century part number consists only of digits and is in the form of“x-xxxxxx-xx”. Extract the middle six digits from that part number and enter it into our search engine for an exact result. A motor model number of any of these varieties can be entered into INYO's product search engine and an exact match can be found.

Step 2

Serial Number (SN) - This number can identify where and when your motor was made it cannot help you track down the replacement. At best you can use this number to contact the manufacturer to narrow the search.

Step 3

Horsepower (HP) - This rating on your pump is the same as the horsepower your car because it is the measure of power output for your motor. For a residential pool pump the range of HP is .5 to 3. The first thought for new pool owners replacing a motor is to think "Bigger is Better", that a more powerful motor leads to a better running or cleaner pool. This is not necessarily the case also you must take into consideration that a new impeller and possibly a new diffuser may need to be bought to accommodate the new motor. The added pressure may also overwhelm filter system if it cannot handle the extra water surging through which may damage your filter or piping.

Step 4

Service Factor (SF) - A full explanation of this rating would take pages but the short of it is that if you multiply the Horsepower by the Service Factor the result is the "Total HP" of your motor. SF for pumps broken into two categories, Up Rated and Full Rated. It is easy to determine which of these your pool pump motor falls into, if you label states the SF is 1.27 or below it Up Rated, anything above it is Full Rated.

Step 5

Frame (FR) - The point where the motor and wet end meet to become the pool pump is called the Flange. The end of the motor that connects to this flange can be shaped in several ways and this configuration is rated on the motor label under the category of Frame. The FR of the pump motor is generally one of four configurations (48Y, 56Y, 56J, 56C). The number "48" or "56" denotes diameter of the motor casing. The letter at the end tells you the shape of the connection, "Y" is square, or "C" and "J" that note a circle flange. As with a circle peg into a square hole a Y-frame will not hook into a C or J.

Step 6

Amps - When you take a look at your power bill and want to know why it is so high, look no further than this rating. The amps will be listed according to volts, Volts = 115/230, the amp rating will be listed respectively for example, 16.0/8.0. The lower the amps the bigger the savings. Your pump may have an energy efficient (EE) replacement motor available that can be substituted for a standard type. The EE and standard motors do not differ in their operation or installation but only in the amount of amps drawn, the EE model drawing a quarter to a third less.

Step 7

Revolutions Per Minute (RPM) - An RPM rating of 3450 is universal for residential single speed pumps if you have a dual speed this rating will be 3450/1725.

Step 8

Phase (PH) - Denotes whether the motor operates on single-phase AC current or three phase AC current. Three phase motors are generally used for commercial purposes.

Step 9

Ambient Temperature (AMB) - Displaying the highest environmental temperature tolerance the motor can withstand, this rating is usually listed as 50 Degrees Celsius. Converted to Fahrenheit that comes to about 122 degrees which would not be a concern unless you live in the Sahara.

Step 10

Time - This denotes the time the motor can operate between shut offs. Pool pump motors are listed as "CONT" for continuous, meaning the motor can run 24/7 without breaks. For normal operation of your pool this round the clock pumping is unnecessary. A six to eight hour run of your pump will keep water clean and clear, as well as save you on the power bill.


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Domingo  Posted: 09/12/2015 8:16 AM 

Very condensed yet accurate and comprehensive explanation. Thanks!

BigT  Posted: 06/23/2013 10:38 AM 

very well presented and useful