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Up-Rated
Versus Full-Rated Pumps and Motors
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This is an area of confusion
that can be fairly easily explained
What is the difference between up-rated or
full-rated? Or is max-rated even better?
By understanding a few key concepts, you can
clearly understand the difference and make an intelligent choice when
selecting the proper pump and/or motor for your pool.
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The
Motor Plate
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The
motor plate will have two very important pieces of information
Horsepower (HP)
- the
horsepower rating of the pump
Service Factor
(SF) - a
multiplier factor
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The
Calculation
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There
is one simple calculation which tells the whole story
Horsepower X Service Factor
= Total Brake Horsepower
If you multiply the horsepower
rating times the service factor, you find out the total
brake horsepower.
The total brake
horsepower of the pump is real power rating of that pump or motor.
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How
Pumps and Motors Get Uprated
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The
motor plate above lists the following ratings for this 3/4 HP
Full-Rated Motor:
| Horsepower
- 0.75 |
Service
Factor - 1.5 |
If
we insert these factors into the equation, we end up with the following
result
| Horsepower |
X |
Service
Factor |
= |
Total
Brake Horsepower |
| 0.75 |
|
1.5 |
|
1.13 |
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Now, suppose you
really wanted to take this motor and call it a 1.0 HP motor instead.
You would just
INCREASE the Horsepower Rating and DECREASE the Service Factor.
| Horsepower |
X |
Service
Factor |
= |
Total
Brake Horsepower |
| 1.0 |
|
1.13 |
|
1.13 |
VOILA
. . . that 3/4 HP Full Rated Motor is now classified as a 1.0 HP Up-Rated
Motor
EXACT SAME MOTOR . . .
DIFFERENT HORSEPOWER RATING
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Some
Examples from Motor Labels
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The
following chart for square flange motors shows how the same motor can be
given two different ratings. These motors come off the same assembly
line. The only difference is the label that is glued on the motor at
the factory.
| Motor |
Horsepower |
Service
Factor |
Total
Brake Horsepower |
| 3/4
HP Full-Rated |
.75 |
1.5 |
1.13 |
| 1.0
HP Up-Rated |
1.0 |
1.13 |
1.13 |
| These
two motors are the exact same thing |
| 1.0
HP Full-Rated |
1.0 |
1.65 |
1.65 |
| 1.5
HP Up-Rated |
1.5 |
1.1 |
1.65 |
| These
two motors are the exact same thing |
| 1.5
HP Full Rated |
1.5 |
1.5 |
2.25 |
| 2.0
HP Up Rated |
2.0 |
1.13 |
2.25 |
| These
two motors are the exact same thing |
| 2.0
HP Full Rated |
2.0 |
1.3 |
2.6 |
| 2.5
HP Up-Rated |
2.5 |
1.04 |
2.6 |
| These
two motors are the exact same thing |
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An
Example From Pump Curves
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perfectly clear from the motor ratings, take a look at the pump
curves. All the manufacturers pretty much do the same
thing. The 3/4 HP full rated pump comes off of the exact same
assembly line as the 1.0 HP up rated pump. All the parts are
the same. The ONLY difference is the label.
Check out this pump curve from Sta-Rite (we've
added a little color to make it nicer looking.) |
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| Line
A |
P4E6DL (3/4
HP Full Rated Pump) |
| P4EA6EL (1.0
HP Up Rated Pump) |
| Line
B |
P4E6EL (1.0
HP Full Rated Pump) |
| P4EA6FL (1.5
HP Up Rated Pump) |
| Line
C |
P4E6FL (1.5
HP Full Rated Pump) |
| P4EA6GL (2.0
HP Up Rated Pump) |
| Line
D |
P4E6GL (2.0
HP Full Rated Pump) |
| P4EAA6GL
(2.5 HP Up Rated Pump) |
Notice
how the 3/4 HP Full Rated and 1.0 HP Up Rated pumps use the same
flow curve . . . that's because they are exactly the same pump. |
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THE
BOTTOM LINE
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THE
BOTTOM LINE . . . the actual horsepower rating of a pump or motor does
not really tell you much. When
it comes time to replace a motor . . . you MUST consider both
the horsepower and service factor. This is
the only way to insure that you are getting the motor that you
need. Consider also the frame size and type of the motor as
well. Don't forget to get a pump seal and appropriate gaskets as
well. When
you are replacing pump parts such as an impeller or diffuser . . .
make sure you match up the exact part number or you may end up with a
mismatched impeller or diffuser. When
it comes time to replace your pump . . . look at the flow
rating. Pay only mild interest to the HP rating.
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