A.O. Smith UST1252 Replacement

Verified specifications

Up-rated vs full-rated: pool pros match total HP (THP = label HP × service factor), not label HP. Never replace a full-rated motor with an up-rated motor of the same label HP — the up-rated motor delivers less total power. Match the THP of the motor coming out of the pump.

56J fitment: threaded C-face mount — the Hayward Super Pump / Super II / Max-Flo and Jacuzzi Magnum class. The 5/8" threaded stainless shaft mates directly to the pump impeller.

Single-speed and CA/NY: California and New York require variable-speed replacement motors (Title 20) for most pool pump replacements. In other states, single-speed replacements remain standard — see the VGreen Evo variable-speed line.

Shaft seal: replace the pump shaft seal whenever the motor is changed — a leaking seal is the #1 killer of new pool pump motors.

Dual branding: this stock number is sold interchangeably as A.O. Smith and Century — Regal Rexnord's aftermarket motor brand. Same motor, same specs; see the Century UST1252 page.

Service factor: published as 1.06 in some tables and 1.10 in others (2.65 vs 2.75 THP) — match the THP on your nameplate.

Confirming the right replacement

Before we quote, compare these fields on your failed motor's nameplate. If any of them differ, send us a photo of the nameplate and we'll match it exactly rather than guessing:

• Full model number — including any suffix letters
• HP, RPM, and voltage
• Frame size (e.g. 284T) and enclosure (TEFC, ODP, etc.)
• Full-load amps

Other A.O. Smith models

• More A.O. Smith modelsBrowse every A.O. Smith model page we quote
• Century UST1252Same stock number under Century branding — identical motor