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Understanding pump ratings and the differences between Full-Rated, Up-Rated, and Max-Rated Last Updated: 08/28/2013 |
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Understanding Motor Ratings When confronted with the need to replace a pool pump or pump motor, the average pool owner is often confused by the terms full-rated, up-rated, and max-rated. These terms can be explained fairly simply once you understand a few key concepts.Calculating the Actual Effective HorsepowerActual Effective Horsepower is the real horsepower of the pump. Actual Effective horsepower can be calculated by multiplying the service factor by the horsepower found on the motor plate as shown below. Actual Effective Horsepower = Horsepower x Service Factor1 1Service Factor (SF) is a concept unique to NEMA design motors and is defined as a percentage by which the motor can withstand an increased load while still maintaining rated torque and speed within an accepted tolerance, even though current is expected to rise. A Numbers GameIt has become common practice for pump manufacturers to play a numbers game with pump ratings. By changing the service factor and the rated horsepower they can
make the SAME PUMP appear to be more powerful to the casual observer by only changing the motorplate. To illustrate this, look at the chart below.
In the first example, the 1 HP full-rated pump is the same pump as the 1.5 HP up-rated (or max-rated) pump, the service factor has just been adjusted to make the HP appear to be greater in the up-rated model. What advantage is there to doing this? For the most part it is a marketing ploy to make a the horsepower appear to be greater when the actual effective horsepower is the same. An uninformed consumer might be willing to spend more to buy a motor rated with a larger horsepower over one with a smaller horsepower when the 2 have the same actual effective horsepower. |