By Century Motors



Part # UST1252

Warranty 1 Year

Dimensions 16" L x 8.5" W x 6.5" D

Alternate Part #'s 12020, 164135, 177022, 184951, 5KCR39UN6181X, 90118597, B231, B231SE, C1149, EB231, JH25UP1, K48N2N106, K48N2N106A1, K48N2N106A3, K48N2N106A9, K48N2N106C2, K48N2N113A6, SP1620Z1M, SP1620Z1MBK, UST1252, V12020, _UST1252, AOS-60-5243, AOSUST1252

Product Description

Voltage 230, Max Amps 230V = 11.2, Single Speed, Round Flange, RPM = 3450, Threaded Shaft, Frame = 56J Used on the following models: Hayward Max Flow, Hayward Super Pump, Hayward Super II, Hayward Northstar and Jacuzzi Magnum pumps.

Note: NOT California Title 20 Compliant. 

California Title 20 Compliant Options:

  • Dual Speed - B2979
  • Dual Speed - Hayward 2.5 HP Dual Speed Up Rate Motor - SPX1620Z2M
Motor Dimensions Motor Dimensions
Motor Image Motor Image

Product Specifications

Motor Name:
2.5 HP UST1252 Replacement Pool Motor
2.5 HP
3450 RPM
208 - 230 V
12.6/11.4 amp
Service Factor:
Total HP:
2.65 HP
Stock #:
Overload Protector:
Dimension Letter:
13 - 1/16 in.
Commonly Used On:
Hayward Max Flow, Hayward Super Pump, Hayward Super II, Hayward Northstar and Jacuzzi Magnum
NOT California Title 20 Compliant

?     Asked on 4/11/2023by stanley botwin

will this fit on hayward model SP2621X25

A  Answered on 4/12/2023 by InyoPools Product Specialist Craig C.

Hello Stanley.  The Century (A.O. Smith) 2.5 HP Up Rate Motor, Round Flange 56J Frame, Single Speed - Model UST1252 is a compatible replacement motor for the Hayward Super Pump SP2621X25.  The Hayward Super Pump Seal Kit - Model GOKIT3 contains the seals and gaskets necessary to complete the UST1252 motor installation.  Attached please find the Hayward Super Pump exploded parts diagram for reference. 

?     Asked on 4/19/2021by al

I am replacing a motor on a sprinkler pump that was a Franklin 56j 2hp. I looks like either the 2hp or 2.5 hp motors would fit. Since they both run at 3450 rpm and i am not changing the impeller, is there any reason to upgrade to the 2.5 hp? I would seem like the flow rate will be the same for either. Thanks

A  Answered on 5/3/2021 by InyoPools Product Specialist Danny R.

You can upgrade to a higher HP, but you have to replace a lot of other parts besides the motor.  So you will need to replace other parts like the impeller, diffuser, and go kits.  Typically if you want to increase the HP I recommend just buying the entire new pump.

?     Asked on 1/5/2021by MARCO MONTOYA

is available in 110 V

A  Answered on 1/6/2021 by InyoPools Product Specialist Joe S.

Hello Marco, at this time we only carry this unit in a 230-volt model. 

?     Asked on 1/1/2021by Benny

What is a recommended replacement motor for this Hayward pump. see attach jpg. Please include cost RS 2000 2.00 Hp 1.25 SF 2.50 THP Just in Case I consider what would be a good dropin pump as well? Please include cost. Thanks


A  Answered on 1/14/2021 by InyoPools Product Specialist Megan C.

The Century 2.5 HP Round Flange 56J Up Rate Motor - UST1252 and California Title 20 Compliant Options: Dual Speed (230V)- B2979 Variable Speed - ECM27CU are motor options. The Tune Up Kit Hayward Super II - GOKIT2 or GOKIT2SALT will be needed when replacing the motor on the Hayward RS Series pump. We do not offer the Super II / RS 2.5HP Pump. The Waterway Champion 2.0 HP Full Rate EE Pool Pump - CHAMPE-120 or Waterway Power Defender 270 PD-VSC270 (California Title-20 Complaint) are other pump options.

?     Asked on 9/17/2020by Robert gilbert

Will Thermal Overload Protector - 610806-095 work on AO Smith motor model K48N2EC15?

A  Answered on 9/18/2020 by InyoPools Product Specialist Matt S.

The correct replacement terminal board for your Century 2.0 HP Square Flange 48Y Full Rate Motor - SQ1202 motor is the 626536-002

  • Commented on 9/18/2020 by Product Owner

    I am inquiring about the part for this ao smith motor for the thermal Overload protector. Not the terminal board.

    • Commented on 10/19/2020 by InyoPools Product Specialist Hector F.

      Robert, the correct thermal overload protector will be the part number 610806-056 for your motor model K48N2EC15.  

?     Asked on 2/23/2020by Nathan

I am about to purchase (replace) the pool filter pump. It is HP 3.0 and total HP = 3.45. I am wondering if this is too big. I recall it was about 2.5 HP for the original. How is the HP determined?

A  Answered on 2/24/2020 by InyoPools Product Specialist Lennox H.

Hi, Nathan. In order to properly size a pump for your pool, use our How to Size a Pool Pump guide.

?     Asked on 5/30/2018by john

hi, i have a in ground pool about 38000 gallons i am using a haywood pump 1 hp the water flow is horrible. I can not turn on all jets (7) 2 floor-3 on the wall-2 at the steps-not enough pressure to push things to the skimmers. I want to upgrade to a 2.5 hp thinking it would be better but i noticed the rpms are the same what are your thoughts.

A  Answered on 6/9/2018 by InyoPools Product Specialist Alex V.

John, Any single speed pump will have the same rpms (3450). If you want to increase the horse power, you need to make sure that your filter and plumbing can handle the increased flow. 

?     Asked on 5/8/2018by Ken

Hi, again: Related to the question about the leakage below. The inserts appear to be fully seated, and the leakage appears come from mostly the very top center area - between two bolts. Any other possibilities? The pump itself is about 11 years old, but not sure what would have caused it to start leaking suddenly. Thank you; Ken

A  Answered on 5/8/2018 by InyoPools Product Specialist Hector F.

If the seals have been replaced and lubed then the only other possibilities will be those bolt inserts or the housing has been warped to the point that they do not seal flush with one another. 

?     Asked on 5/8/2018by Ken

I have a UST 1252 motor connected to a Hayward Super II Pump. This motor is about 2 years old. It has begun to leak around the top of the seal between the motor and pump. I did replace the seal using your GO kit, but it made no difference. Cleaned the surfaces real well and the bolts are tight. It is a fair amount of leakage and definitely from top area, not the bottom. Suggestions/causes? Thanks: Ken

A  Answered on 5/8/2018 by InyoPools Product Specialist Hector F.

The Super 2 series has been known to get leaks at the bolts where the housing meets the motor. The bolt ports are known to separate from the housings. If that is the case then you can use the pump housing repair tap set part number 5110-22.

?     Asked on 5/30/2016by Mike

I am looking to replace a pool motor UST 1252. Found in on your webpage along with tune-up kit. I was having pump leak problems at the seam between pump and main housing. Thinking of replacing at same time. Do you have a complete kit or only parts ?

A  Answered on 5/30/2016 by InyoPools Product Specialist Patrick P.

Hi Mike, we may have a kit but we would need to know the make and model of your pump. This should be something like Hayward Super Pump, Hayward Super II, Jacuzzi Magnum, etc.. Could you please email back with your pump details.

?     Asked on 7/14/2015by Ken

I have a 2 year-old UST1252 motor. I believe the start capacitor is failing - perhaps the run capacitor as well. The pump generally does not start (hums and then shuts down and/or breaker trips) the first time after sitting for a while. Flow seems good once it runs and the impeller seems to move freely (I have only reached in through strainer side, have not removed the pump (yet). All that said, can you tell me the size/ratings for the capacitors? Thanks! Ken

A  Answered on 7/16/2015 by InyoPools Product Specialist Lennox H.

Hi Ken, The A.O. Smith (UST1252) uses a Run Capacitor 30 MFD 370V (5VR0303) and Start Capacitor 36-43 MFD 120V  (BC-36).


Est. Repair Time

Less than 1 hr

Tools Needed

Screwdriver, Pliers, Socket Set, Adjustable Wrench

Failed super pump motor

Written on 9/30/2020 by Guest

Remove 4 exterior Motor to pump bolts
Remove next 4 bolts on bezel
Loosen rear metal cover screws
Remove impeller by securing the driveshaft nut and turning the impeller
Remove next two covers attached to motor
Turn off breakers
Remove electrical
Replace gaskets, seals and impeller spring
Reassemble in reverse with new motor

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