It is important that a replacement motor should have a maximum horse power more than or equal to the horse power of the old motor. This is because h.p. is always matched to the size of the impeller (ie. a two h.p. motor will be adequate to drive any impeller sized two h.p. or less, but a one h.p. motor will overheat and fail prematurely if it is driving an impeller larger than one h.p. in size.)

Always multiply a motor's h.p. with it's service factor (ie. a 1 1/2 h.p. motor with a service factor of 1 has a total h.p. of 1 1/2, but a 1 1/2 h.p. motor with a service factor of 1.4 has a total h.p. of 2.1.). Service factor is a multiplier and multiplying the service factor by the h.p. equals the total h.p. that the motor is capable of at rated voltage and frequency. When replacing an existing motor the total h.p. times the service factor of a replacement motor should be more than or equal to the total h.p. times the service factor of the original motor.

Given this equation, the horse power rating of any given motor is, by itself, irrelevant unless multiplied by its service factor. As each motor rolls off the production line the manufacturer can produce the desired total h.p. by adjusting these two factors. For one last example, a 2 h.p. full-rated motor with a service factor of 1.3 has a total h.p. of  2.6, the same as a 2.5 up-rated h.p. motor with a service factor of 1.04.

To avoid confusion, PoolsOnly.com sells only full-rated motors, though some of our pumps are equipped with up-rated motors as determined by the manufacturer's specifications.