18
Pump Motors
Level 2
A.O.Smith
When running at shut off the energy is convert-
ed to heat. The water in the pump casing can
boil under pressure to the point where a plastic
impeller is melted. Some of the heat goes into
the motor shaft and back to the bearing causing
possible failure.
If a jet pump is used as a centrifugal pump
with the jet assembly removed, the motor may
overload particularly in a flooded suction condi-
tion. Flooded suction means water is available to
the pump without the pump having to create a
suction lift.
Jet pump motors may be either single voltage
(115 or 230 for example) or dual voltage
(115/230). On original equipment, 115 volt 1/3
and 1/2 HP units are common since there is
enough volume to warrant a separate model with
a slightly lower motor cost. Most replacement
motors are dual voltage and factory connected for
high voltage. If 115 volts are applied to a motor
connected for 230 volts, the motor will just hum
and probably not turn. In the reverse condition,
the motor will immediately burn out.
The motor will not run faster or be more effi-
cient on the high voltage, but a smaller wire size
may be used since the amps at 230 volts are one-
half the amps at 115 volts.
A dual voltage motor is sometimes temporarily
run on low voltage at a new home site until the
permanent power supply is available.
