of Pump and Motor Terminology
Here is some terminology used in context
with motors and pumps that you should be familiar with:
Air gap- The air space between two magnetically
related or electrically related parts. (i.e the
poles of a magnet or the poles of an
Alternating current- An electrical current that alternates, flowing first with
a positive polarity, followed by a negative polarity.
Capacitor- An electrical device consisting of two or more conducting plates
separated from one another by insulating material and used for storing an electrical
Dielectric-The insulating material that separates
and insulates the conducting plates in a capacitor.
Dielectric breakdown- The failure of an insulating material to separate electrical
charges. Breakdown occurs when the insulating material changes and conducts
the electrical charge between plates.
Frequency- In electricity, the number of times alternated
current changes direction during one second. Frequency is measured in hertz.
Hertz- A unit of measurement of frequency. Hertz indicates "cycles per
second" of alternating current.
Horsepower- The conventional unit of measure foi- power, this
indicates the result of force multiplied by distance multiplied by time.
Locked-rotor test- A test of an electric motor in which the
shaft is prevented from turning while power is applied.
NEMA- The National Electrical Manufacturers Association.
No-load test- Operating a motor at full speed with no load to determine rotational
Rotor- The rotating part of an electric rotating machine. In a motor it is
connected to and turns the drive shaft. In an alternator or generator it is
produce electricity by cutting magnetic lines of force.
Service factor- A measure of the reserve margin built into a motor. Motors
rated more than 1.0 SF have more than normal margin and are used where unusual
such as occasional high or low voltage, momentary overloads and so forth are
likely to occur.
Single phase- Having only one alternating current or voltage in a circuit.
Stator- The stationary part of a motor that contains the laminated steel core
with the winding; this is where the rotor revolves.
Torque- A force that produces a rotating or twisting action.
Triac- An electronic switch used in applications such as power switches, light
dimmers and motor controls.
Voltage- Electrical pressure; the force that causes current in an electrical
Watt- A unit of electrical power representing the power developed in a circuit
by a current of one ampere when the voltage drop is one volt.
Wattmeter- An instrument for measuring electrical power.
Capacitor-start motor- An alternating current split-phase
induction motor that has a capacitor connected in series with an auxiliary
winding for starting.
The auxiliary circuit disconnects when the motor is up to speed. This
motor requires an internal starting switch and governor.
Permanent split capacitor motor- A single-phase electric motor that uses
a phase winding in conjunction with the main winding. The phase winding
by a capacitor that stays in the circuit at all times and is rated for
continuous running. The capacitor improves starting and running power factors.
does not require either an internal starting switch or a governor.
A single-phase induction motor that has an auxiliary winding connected
in parallel with
the main winding.
The auxiliary winding's magnetic position is not the same as the main winding,
so it can produce the required rotating magnetic field needed for starting.
This motor requires an internal starting switch and a governor.
Three-phase electric motor- A motor that operates from a three-phase power
source. In three-phase power, three voltages are produced that are 120
apart in time. This motor has no internal starting switch.
Two-capacitor motor- An induction motor that uses one capacitor for starting
and one for running. The starting capacitor is in parallel with the running
capacitor as the motor is starting; at 75 percent of speed, the starting
capacitor is cut out of the circuit. This type of motor is sometimes called
start/capacitor run and requires an internal starting switch and governor.
Pool and spa pumps are classified as centrifugal pumps. Meaning, the centrifugal
force that is created by spinning the water, will force the water downwards
and if there is an opening or a hole, this water will get pushed forward
through the hole.
The pump operates the same way. The impeller in the pump spins, shooting water
out of it. As the water escapes, a vacuum is created that demands more water
to equalize this force. Water is pulled from the pool or spa and sent on its
way through the circulation plumbing. The hole size determines the amount of
water and how fast it can escape.
Pumps used for pools are self-priming. That is, they expel the air inside
upon start-up, creating a vacuum that starts suction. Once water is flowing
through the pump, if you close a valve on the outflow side of the pump, restricting
all flow, maximum possible pressure is created.
Strainer Pot And Basket
Water flows into a chamber, called the strainer pot or hair and lint trap.
This chamber holds a basket that permits water to pass but retains the debris.
some pumps the strainer pot bolts to the volute with a gasket to prevent leaks,
while in yet others it is molded together with
the volute as one piece. In bathtub spas or booster pumps, there is no strainer
pot and basket at all since debris is not a problem.
There is an access provided to clean out the strainer basket, and also have
a cover that are usually made of transparent plastic and can easily be attached
with a nut and a bolt. The strainer cover has an O-ring between the lip of
the strainer pot and itself. This prevents any leakage due to suction. Also
the pot has a small threaded plug that screws into the bottom. This plug is
designed to allow complete drainage of the pot when winterizing the pump.
The volute, is the chamber in which the impeller spins, that forces water
out of the pump and into the plumbing that takes the water to the filter. The
outlet port is usually female threaded for easy plumbing. The movement of the
impeller sucks the water from the pool through the strainer pot. The resulting
vacuum in the pot is compensated for by water filling the void. The rushing
water is contained by the volute which directs it out of the pump. Therefore
the pot can be considered a vacuum chamber and the volute a pressure chamber.
The impeller by itself cannot create a strong vacuum by itself to make the
flow begin. The area immediately around the impeller must be limited
to eliminate air and help start the water flow. A diffuser and/or closed-face
impeller help this process, but in many pump designs, the volute serves this
The impeller is a ribbed disk that spins inside the volute. The disk is called
a shroud and the curved ribs are called vanes. Water entering the center of
the impeller, is forced to the outside edge of the disk by the vanes. As the
water moves to the edge, there is a resulting drop in pressure at the center,
creating a vacuum that is the suction of the pump.
There are two types of impellers, closed-face and semi-open-face. In a closed-face
impeller, the vanes of the impeller are covered in both front and back. Water
flows into the hole in the center and is forced out at the end of each vane
along the edge of the impeller. This type of impeller is very efficient in
moving water and a diffuser is added to the design to slow the speed of the
water before it leaves the volute. This design does not take into considerationthe
debris that might escape the skimmer and strainer basket and into the impellers.
This led to the new design, the semi-open-face design allowing small debris
to pass by actually pulverizing it. Diatomaceous earth is the chief cause of
clogging in the impellers.
Impellers are rated by horsepower to match the motor horsepower that is used.
This, in turn, determines the horsepower rating of the pump or pump and motor
you have. Usually the motor is of higher horse power than the impeller.
Seal Plate and Adapter Bracket
The volute is divided into two sections, the rounded volute and the seal plate.
This allows an access to the impeller. The seal plate is joined to the volute
with a clamp or with bolts. An O-ring between them makes this joint watertight.
The motor is bolted directly onto this type of seal plate. In other designs,
the seal plate is molded together with an adapter bracket that supports the
motor and bolts to the volute, with a paper or rubber gasket between them to
create a watertight joint.
In both cases, the shaft of the motor passes through a hole in the center
of the seal plate and the impeller is attached, threaded onto the shaft. The
bracket allows access to the shaft extender for adjusting the clearance between
the impeller and volute. The pump design of closed face needs no such adjustment,
so the shaft need not be exposed.
Shaft and Shaft Extender
The shaft of the motor is the part that turns the impeller, creating water
flow. The impeller needs to be adjusted in relation to the volute, so a shaft
extender has been created. The extender slides over
the motor shaft and is secured by three allen-head setscrews. The male threaded
end of the shaft extender then fits through the seal plate and the impeller
is screwed into place.
The extender is round with a flat area on two sides to prevent the extender
from spinning when performing maintenance.
The shaft should never be in contact with electric current, so most motor shafts
today are designed with a special internal sleeve
to insulate the electricity
in the motor from the water in the pump.
The seal allows the shaft to turn freely while keeping the water from leaking
out of the pump. If the shaft passed through the large hole of the seal plate
without some kind of sealing, the pump would leak water.
The seal is in two parts. One half of the seal is composed of a rubber gasket
or O-ring. This is fitted around a ceramic ring and fits into a groove in the
back of the impeller. The
other half of the seal is made of a metal bushing and a spring. This fits into
a groove in the seal plate. Since the spring
exerts pressure on both the sides it makes the whole seal water tight there
by preventing the water from leaking out of the pump.
As the shaft turns, these two halves spin against each other but do not burn
up because their materials are heat-resistant and the entire seal is cooled
by the water around it. Therefore, if the pump is allowed to run dry, the seal
is the first component to overheat and fail. Pumps are not designed to run
without water for more than a few minutes while priming.
Motors are rated by horsepower. The most common ratings for pool and spa
motors range from 0.5 to 2.0 horsepower. Some motors are designed to operate
at two speeds. Each speed is dependent upon the need for circulation and heating
or for jet action in a spa. A starting switch is mounted on one end with a
small removable panel for maintenance access.
A thermal overload protector, which is a heat sensitive switch that is like
a circuit breaker, is mounted on the panel. If the internal temperature gets
it shuts off the flow of electricity to the motor to prevent greater damage.
As this protector cools, it automatically restarts the motor. But, if the unit
overheats again, it will continue to cycle on and off until the problem is
solved or the protector burns out.
The capacitor of the motor is located on top of the motor housing in a separate
box or housing. The capacitor has the ability to store an electrical charge,
and when discharged it gives the motor enough of a jolt to start. This way
the capacitor can impart enough energy to start the motor and then run on a
lower amount of electricity.
Without the capacitor, the motor would need to be served by very heavy wiring
and high-amp circuit breakers to carry the starting amps.
The three main types of motors that you find in pool and spa are:
When the start up power requirements are minimal, the motor is usually one-quarter
horse power or less. This does not require any capacitor either.
Capacitor start, induction run (CSI)
This is the most commonly used motor in the pool business. This motor uses
a capacitor and starting windings to start up, then these are shut down and
a running winding takes over.
The capacitor and start-up
windings allow faster, stronger torque to overcome the initial resistance
of the impeller against standing water. When the water is moving and less
power is needed to keep it moving, the system shuts off and the lighter running
winding takes over.
Capacitor start, capacitor run (CSR)
A (CSR) motor is more efficient than a (CSI) motor, but costs more
because of the added parts.
These motors are also called switch-less, because on some designs the run capacitor
start switch unnecessary. These are the most energy efficient motors when they
have heavier wire in the windings to lower the electricity wasted from heat
loss. A good way to compare energy efficiency between two motors is to compare
the gallons pumped to kilowatts used. The higher the resulting number, the
more efficient is the pump and motor. Kilowattage is determined by multiplying
amps by voltage.
Motors are most commonly designed to work on 110 or 220 volts. Higher horsepower
motors might run on three-phase current. So it is best to get the work done
by a certified electrician.
A variety of motors are designed for pool pumps. The motor
must be compatible to the pump design. The motor face could be either a C-frame
or square-flange type.
So, check for the correct fit and compatibility with the pump.
The service factor of a motor is a multiplier number. When this number is
multiplied with the horsepower rating of the motor, you get the real horsepower
at which the motor is designed to operate on a continuous basis. As an example,
a motor rated at 1 hp with a service factor of 1.5 can actually safely run
a 1.5-hp pump (1.0 x 1.5 = 1.5 hp).
Usualy, a diagram showing how to wire the starting switch plate for 110 or
220 volt supply can be found on the outside of the motor. If not, remove
access door in the end bell and it should be printed on a sticker in there.
These stickers frequently come off as the motor gets older, so if no diagram
is available, refer to the manufacturer's guidebook available at your supply
The nameplate also tells you of the maximum load or amperage. It might say "10.0/5.0." This
means the start-up draw is 10.0 amps, and the normal running draw is 5.0 amps.
The nameplate also lists the electrical phasing and cycle frequency in hertz.
Pool and spa motors are designed for continuous duty, meaning they can run
24 hours a day for their entire service life without stopping. The nameplate
shows this by the rating "Continuous Duty." The horsepower, service
factor, rpm, and frame style of the housing are listed. If the motor has a
thermal overload protector, the nameplate will indicate it.
Horsepower And Hydraulics Equals Sizing
To find the correct horsepower of the motor or the pump, that is required
for the job, it is best to consider the needs of the pool and spa, hydraulics
involved and the horsepower of the equipment. This gives you the right
of the unit that needs to be installed.
The study of water flow and the factors affecting that flow is Hydraulics.
It is important to understand because its principles affect plumbing and equipment
sizing choices for there are so many factors involved.
Terms commonly used
Head and Flow rate- Head is the resistance of water flow
through plumbing and equipment expressed in feet. The lower, the better. Flow
is the volume
of water moved in a given period of time.
As the length of the plumbing pipe increases, the resistance will bring down
the flow rate.The additional resistance (head) of that added pipe means that
the pump cannot push the water as fast. This loss of flow, as head increases,
is called head loss. What is actually lost is flow.
The term actually means flow loss caused
you continue to increase the head (resistance) by adding more vertical pipe,
the flow rate will continue to decrease until at last, no water comes out at
Pumps are designated low, medium, high, or ultra-high head. The higher the
head designation, the less strain is placed on the pump and motor components:
Low head-suck well; push poorly; Medium head-suck well; push well; High head-suck
poorly; push well (most common in pools and spas); Ultra-high head-suck poorly;
push well (pool sweeps).
One factor affecting which type a particular pump will
be is its impeller. Thin vents on the face (closed or semi-open) result in
greater push but poor
suck; in other words, poor self-priming capabilities but good circulating
Suction Head is the head created by adding resistance to
the outflow side of the pump. By restricting the intake or requiring the pump
to lift water from a source below it, you also create head.
Each foot on the suction side equals a similar foot on the discharge side,
called discharge head. The
only thing to remember here is that head (resistance) is created on both sides
and must be calculated when determining pump size.
Dynamic and Static Head- The
static head or the head created by the weight of standing water is only
a small portion
of the total head in the system. The rest is created by the friction of water
flowing through the entire system, called dynamic (moving) head. The diameter
of the pipe and the speed of the water determines how much resistance is created
by friction. Further friction is created when water must go through or around
other obstacles, such as through the filter, heater, solar panels, and plumbing
fittings for every plumbing elbow or bend creates head too.
Cavitation refers to the vacuum created when the outflow
capacity of a pump exceeds the suction intake. This happens, when
a pump is oversized
for the suction line or when the distance from the body of water is too far.
The result is bubbling and vibration.
Total Dynamic Head (TDH) is the total of plumbing and equipment head for the
entire system. Vacuum head (suction) plus pressure head (discharge) equals
total dynamic head.
Shut-off head- The amount of head at which the pump can no longer circulate
Calculations: Here are a few general numbers to use in your calculations.
To make it easier to calculate head in your plumbing system,
it is measured for every 100 feet of pipe or the equivalent. Plumbing connections,
fittings, and valves have different amounts of resistance than straight pipe.
So, these must first be converted to the equivalent length of straight pipe.
Unions and straight connectors act like additional lengths of straight pipe.
So, no special calculations are needed. Going around corners is what creates
head. Here are the values for the most common PVC fittings you will use:
1) 1/2-inch x 90-degree elbow = 7.5 feet of straight 1/2-inch pipe
2) 2-inch x 90-degree elbow = 8.6 feet of straight 2-inch pipe
3) 1/2-inch x 45-degree elbow = 2.2 feet of straight 1/2-inch pipe
4) 2-inch x 45-degree elbow = 2.8 feet of straight 2-inch pipe
Filters- The manufacturer will
tell you in the literature that accompanies the product how many feet of head
the unit creates.
You can also measure the amount by placing a pressure gauge on the pipe leading
into the filter and one on the pipe going out. The difference, measured in
pounds per square inch (psi), tells you the feet of head.
Manufacturers recommend cleaning a filter when the operating pressure
builds up to more than 10 psi over clean operating pressure. Heaters create
8 to 15 feet of head. Like filters, the manufacturer will tell you in the literature
that comes with the unit what the head loss is for the
unit at a given flow rate. Also like filters, as scale builds up in the heat
exchanger, more friction is created and therefore more head.
Poolside Hardware- Main drain covers, skimmers, and return
outlets all add head. To know exactly how much, you must refer to each manufacturer's
A general rule of thumb is to add 5 feet of head to allow for the total of
such components in your system.
Pumps- also create head, but the manufacturer's charts
allow for this, so your calculations need not consider it. When you look at
the TDH for the
system on the pump curve, the pump head loss is already figured in the performance
Turnover Rate- The turnover rate of a body of water is how
long it takes to run all the water through the system. It is desirable for
the water to completely
circulate through the filter one to two times per day. Various components offer
more or less resistance at different speeds expressed in gallons per minute.
To calculate the TDH of a system, you must know that
speed. To decide what speed is needed
you must establish a turnover rate.
Let's say you've calculated the volume of water in the pool as 24,000 gallons.
24,000 gal / 6 hrs = 4000 gallons per hour 4000 gph / 60 min = 66.6
Therefore, you need a pump capable of delivering a flow rate of 66.6 gpm under
the TDH of the system.
Methods of calculating TDH: Here are the three methods for calculating TDH.
Method 1: Exact values:
If you have the exact specifications of the pool,
measure all the pipe from the pool, through the equipment, and back to the
pool. Add the equivalent feet of pipe for all the fittings. Add the feet of
head at the desired flow rate for the filter, heater, and any other components
to arrive at the TDH for the system.
Method 2: Estimated values:
1) Suction-side head- Assume 2 feet of head for each 10 feet the equipment
is away from the pool.
2) Discharge-side head- Estimate how many feet of pipe are in the system back
to the pool. Double that estimate to allow for fittings.
3) Using the tables, calculate the feet of head for the total amount of pipe
on the discharge side.
4) Equipment head. Consult manufacturer's tables and charts for the desired
5) Add these three parts together to get the TDH.
Method 3: Measured values:
An easier and more accurate way to estimate all of this, if the existing pump
is operating, is to measure the vacuum on the suction side of the pump and
the pressure on the discharge side. Plumb a vacuum gauge on the pipe entering
the pump. It measures inches of mercury. Every 1 inch of mercury equals 1.13
feet of head. Plumb a pressure gauge on the pipe coming out of the pump. It
measures pounds per square inch (psi). Every 1 psi of pressure equals 2.31
feet of head.
Multiply the gauges out accordingly and the sum of the two gives you the TDH
of the system. This might sound like work, plumbing in two separate gauges,
but it really isn't, and it gives you the most accurate TDH calculation because
it takes into account the dirty filter, the limed-up heater, all the unseen
plumbing. It also allows you to keep an eye on the TDH in the system at any
time and more easily troubleshoot poor performance in the equipment.
The running water not only encounters friction created by pipes and equipment,
but the water itself is creating friction. This friction will strip copper
from pipes and heater components causing all kinds of havoc. Because of this,
most building codes set maximum flow rates of 8 feet per second through copper
pipe and 10 feet per second through PVC. Since heaters
all use copper heat exchangers, use 8 feet per second even if the plumbing
What is feet per second in terms of gallons per minute?
1) 50 gpm in 1 1/2-inch pipe = 7.9 feet per second
2) 50 gpm in 2-inch pipe = 4.8 feet per second
3) 60 gpm in 1 1/2-inch pipe = 9.5 feet per second
4) 60 gpm in 2-inch pipe = 5.7 feet per second
Maintenance And Repair
It is always better to keep the pump and the motor in good condition for
they affect the efficiency of the system. Keep the motor in good working
by keeping it dry and cool. Also, do not allow the bad and worn bearings
to take a toll on the motor. Attend to any leaks as soon as detected
in the pumps as
they will eventually affect the motors. The basic repairs and maintenance
of the pump and motor unit are discussed in the following sections.
When the strainer basket gets clogged with debris and dirt, clean it out.
Even small amounts of hair or debris can clog the fine mesh of the basket and
reduce flow. For this, you have to shut down the system, remove cover bolts
or clamps, clean out hair and filth from the basket, put the basket back, find
a water source to fill the pot so the pump will reprime easily, check the O-ring,
replace the cover, tighten the bolts or clamps, and restart the system. If
the basket or the pot is broken or cracked, the basket will permit large debris
to clog the impeller or the plumbing between the equipment components.
Gaskets and O-Rings
Most problems occur in strainer pots when the pump is operated dry, with
no water to cool it. The strainer basket will eventually melt. The pot cover,
if plastic, will warp. The O-rings will melt.
Replacement of the parts should be done in such cases.
When gaskets leak, the replacement process is the same as removing
the strainer basket. Remove the strainer pot. Clean out the old gasket thoroughly.
Reassemble the new gasket and strainer pot the same way the old one came off.
Tighten the bolts evenly. Sometimes the bolts are
designed to go through the opening in the pot and volute and are tightened
with a nut and lock washer on the other side. Be careful in assembling these
When removing and replacing the strainer pot cover, be sure the O-ring and
the top of the strainer pot are clean, because debris can cause gaps in the
seal. Sometimes, these O-rings become too compressed, dried out, and brittle.
Then it can't seal the cover to the pot. Then replace the O-ring.
Changing A Seal
All pumps have seals to prevent water from leaking out along the motor shaft.
When these wear out due to overheating, they are easy to replace. Make sure
to turn off the electricity to the motor at the breaker before starting.
1) To access this seal for replacement, remove the four bolts that hold the
pump halves together.
2) Grasp the motor and pull it and the bracket away from the volute. Wiggle
it slightly from side to side as you pull back to help break this joint.
3) Take your pliers or a wrench and hold the shaft extender to prevent it from
turning. Unscrew the impeller from the shaft extender using an impeller wrench.
4) Remove the four bolts that hold the bracket on the motor. If needed, use
a hammer to gently tap the bracket away from the motor.
5) Remove both halves of the old seal. Make sure to recognize how each half
is installed so you get the new one back in the same way. One half is in the
and is easily popped out with a flat-blade screwdriver. The other half is in
the seal plate and motor bracket unit.
6) Install the new seal. First, look up your pump in the manufacturer's literature
to determine the model seal required. Failing that,
you can take the old one to a supply house so they can match it up for you.
There are only three commonly used seals in pool and spa work. Clean out the
seal plate and impeller at the old seal. An emery
cloth or a small wire brush and water will suffice.
7) When you break apart a pump, the old gasket usually won't reseal.
Clean all of the old gaskets off of the seal plate and volute. Scrape it clean
if needed with flatblade screwdriver. Now reassemble the pump by
placing a new gasket between the pump halves.
8) Check for leaks by starting the pump and let it run several minutes. A fresh
paper gasket might leak for a few minutes until it becomes wet and swells to
fill all the gaps. But, it should stop leaking after a short time. If your
job does leak, take it apart and go over each step again.
In some pumps where the parts are assembled slightly differently, you follow
the same steps. The clamp is removed to disassemble the pump halves, and then
remove the diffuser to get to the impeller. To remove the impeller, you can
with your hand and twist it off. But, the trick with these units is to stop
the shaft from spinning as you twist off the impeller. There are air vents
in the motor on the end closest to the pump itself. Look in and you will
see the motor shaft. Place a flat-blade screwdriver in one of the air vents
wedge it against the shaft to keep it from turning.
Alternatively, you can remove the end cap and look inside as you twist the
impeller. You will see the back end of the shaft, with the start switch attached.
Since this switch is fragile, you must remove it to access the
slotted screw in the back end of the shaft. Place the screwdriver in this screw
to keep the shaft from turning as you remove the impeller. Instead of a gasket,
some pumps use an O-ring. Clean this and lubricate it with silicone before
Some pumps use a plastic impeller with a housing that holds half the seal
in place. If the pump has run dry and overheated the pot, this housing might
be warped and the seal will not fit tightly. The only solution is to replace
the impeller. This is a common problem with automatic cleaner pumps, which
are not self-priming.
Pump And/Or Motor Removal And Reinstallation
Sometimes it is necessary to remove an entire pump and motor unit to take
do a repair. If the pump is damaged beyond your ability to
repair it, you probably will want to take the entire unit to a motor repair
shop. They can rebuild it as needed, and you can reinstall it.
remove the pump and motor as a unit, the first thing is to turn off the circuit
breaker. Now you will need to cut the plumbing on the suction and
return side of the pump. Leave a few inches on both the sides of the cut
to replumb it by slip couplings.
Whenever installing the plumbing between the pump and filter,
keep bends and turns to a minimum. Also, do not locate the pump close to the
of the filter. When you open the filter for cleaning, water is sure to flood
the motor. Lastly, try to keep motors at least 6 inches off the ground, to
prevent it from flooding during rains.
The electrical connection must be removed before the pump and motor can be
disengaged. Remove the access cover to the switch plate area of the motor.
This is near the hole where the conduit enters the motor. Remove the three
wires inside the motor and unscrew the conduit connector from the motor housing.
conduit and wiring away from the motor and the entire pump and motor should
be free. If there is an additional bonding wire (ground wire), it can be easily
removed by loosening the screw or clamp that holds it in place.Tape off the
ends of the exposed wires, and leave a note on the breaker box, as a warning.
the unit on a solid, vibration-free base. Make sure there is adequate drainage
in the area so that
when it rains or if a pipe breaks the motor won't be drowned. Bolt or strap
down the pump. Plumb in both suction and return lines with as few twists and
bends as possible, to minimize head. A gate valve on both sides is advisable
to isolate the pump
when cleaning other components. A check valve is essential if the unit is well
above water level. Plumb the unit far enough away from the filter that it won't
get soaked when you take the filter apart.
Replacing A Pump Or Motor
any of the components is simply a matter of disassembling the pump to
the component that needs replacement, getting a replacement
part, and reassembling the unit. Of course, if the entire pump and motor is
to be replaced, the re-plumb it in as previously
Sometimes the motor will trip the circuit breaker when you try to start it.
If this happens it is usually because there is something wrong with the motor.
However, it could be a bad breaker, or one that is simply undersized for the
job and has finally worn out. To replace the motor here are the procedure:
1) Break down the unit as described in the section on changing a seal. Remove
the shaft extender by removing the allen-head setscrews and pulling the extender
off the motor shaft. Use your large flat-blade
screwdriver to pry the extender away from the motor body. Sometimes corrosion
will eat away at the setscrews and extender-if it is too tough to remove, replace
2) Before sliding the shaft extender on the new motor, clean the motor shaft
with a fine emery cloth.
a light coat of silicone lube to the shaft. When you put the extender on the
motor shaft, the setscrews go into a groove that runs along the shaft. This
groove allows the screws to grip and not slide around the shaft.
3) Now slide the new extender in place, making sure to line up the setscrews
along the channel, but do not tighten the setscrews. When you have reassembled
seal plate, seal, and impeller, you can adjust the impeller to just barely
clear the seal plate face, and then tighten the setscrews. Be sure the impeller
is screwed tightly onto the shaft extender before making this adjustment. If
it is loose, when the motor starts it will tighten the impeller by turning
it tighter against the extender. Therefore, tightening it against the seal
plate, seizing up the unit.
4) Secure the shaft extender with your pliers or 3/8-inch box wrench and lay
a rag over the impeller. Firmly hand tighten it. Reassemble the remaining pump
parts and/or replumb the entire unit back into place.
5) You can access the electrical connections through the switchplate cover
in the front end bell.
The first and most common motor problem is water, which may be due to several
reasons like rain, filter cleaning, or breaking of a pipe. In all cases,
dry the motor
and give it 24 hours to air dry before starting it up.
Even small amount of moisture can short the motor. Other basic problems beyond
dealt with in the following fashion.
Motor Will not Start
Check the breaker panel and look for any loose connection of the wires to
the motor. Sometimes an electrical supply wire connected to the motor
switch plate becomes dirty. The dirt creates resistance that creates heat which
ultimately melts the wire, breaking the connection. Similarly, if the supply
wire is undersized for the load, it will overheat and melt. Clean dirty switch
plate terminals and reconnect the wiring.
Motor Hums but Will not Start
The impeller may be jammed with debris. Turn off the breaker, and spin the
shaft by hand. If it won't turn freely, open the pump and clear the obstruction.
If it does spin, check the capacitor. Check the capacitor for white residue
or liquid discharge. If either exists, it means a bad capacitor. To replace
the capacitor, remove the cover that holds it
on top of the motor. The two wires
are attached to the capacitor with simple push-on and pull-off bayonet clips.
After installing a new capacitor, the motor may hum and yet fail to run because
of insufficient voltage. Use a multimeter to check the actual voltage.
Loud Noises or Vibrations
This is most often caused by worn out bearings. Take the pump apart and remove
the impeller and water. If the motor still runs loud or vibrates, it
is most likely the bearings. In a few instances, the problem can be caused
by a bent shaft. Unless
the motor is relatively
warranty, you might want to replace the motor.
The Breaker Trips
Disconnect the motor and reset the breaker. Turn the motor switch or time
clock switch back on, and if it trips again, the problem is either a bad
breaker or, bad wiring between the breaker and motor. Be very
careful with this test. Switching the power back on without any appliance connected
means you are now dealing with bare, live wires. Be sure no one is touching
them and that they are not touching the water, each other, or anything else.
If the breaker still does not trip, the motor is bad. This usually means there
is a dead short in the windings
needs to be replaced.
Priming the Pump
Priming is starting the suction that gets water moving through the pump, thus
creating circulation in the pool. Most of the modern pumps are self priming,
but when the water gets drained from the pump, it sometimes needs to be reprimed
before it can get started.
The basic steps to prime the pump in most pools and spas:
1) Check the water level in the pool. The
pump will not prime unless filled to the very top of the skimmer.
2) Check the water path. Priming problems are not related to
the pump, but to some obstruction. Check the main drain and the skimmer throat
for leaves, debris, or other obstructions. With the pump turned off, open the
strainer pot lid and remove the basket and dispose off the leaves and debris.
Last, make sure the pump is primed and all valves are open with
no other restrictions in the plumbing or equipment of the pump.
3) Fill the pump. Always fill the strainer pot with water and replace the lid
tightly. Keep adding water until the pot overflows.
Sometimes the pump is installed above the pool water level so you will never
pipe unless a check valve is
in the line as well. Quickly, just fill what you can and close the lid.
4) Start the motor and open the air relief valve on top of the filter. The
pump is primed when all the air is replaced with water and the normal circulation
begins. It is advisable to wait for couple of minutes for the pump to prime,
but at the same time, make sure that you do not overheat by running a dry pump.
The Blow Bag Method
When basic priming fails, try a drain flush bag, also known as a blow bag.
The drain flush is a canvas or rubber tube that screws onto the end of your
hose. Slip this into the skimmer hole that feeds the pump and turn on the hose.
The water pressure makes the bag expand and seal the skimmer hole. This way,
water from the hose cannot escape and must feed the pump. After running the
a minute or two, turn on the pump. When air and water are visibly returning
to the pool, pull the drain flush bag out quickly, while the pump is running,
so pool water will promptly replace the hose water.
This method is not effective if the skimmer has only one hole in the bottom.
The reason for this is the hole is connected not only to the pump, but also
the main drain. The forced water from your drain flush bag will take the line
and flood through the main drain rather than up to the pump. In the two hole
skimmer, the hole furthest from the pool usually is plumbed directly to the
pump. Your drain flush bag in this hole will give good results.
Filter Filling Method
Another method is filter filling. Open the strainer pot, turn on the motor,
and feed the pot with a garden hose. Open the filter air relief valve until
the filter can is full. When it is full, water will spit out of the air relief
valve. Close the air relief valve, turn off the motor and garden hose, and
quickly close the strainer pot. The, open the air relief valve. The filter
water will flood back into the pump and the pipe that feeds the pump from the
When you think these are full of water, turn the motor back on. The pump should
Detecting Air Leaks
When all other methods fail, then there is the problem with an
air leak. The pump is sucking air from somewhere in the system.
Air leaks are usually in strainer pot lid O-rings, or the pot and/or lid itself
has small cracks. The gasket between the pot and the volute might be dried
out and leaking. Of course, plumbing leading into the pump might be cracked
and leaking air.
If any of these components leak air in, then water will leak out. When
the area around the pump is dry, carefully fill the strainer pot with water
and look for leaks out of the pot, volute, fittings, and pipes. Another way
is to fill and close the pot, then listen for the sizzling sound of air being
sucked in through a crack as the water drains back to the pool.
Many pumps employ threaded T-shaped bolts that secure the lid to the strainer
pot. Sometimes these corrode and snap off.
If part of the broken bolt extends above or below the female part on the pot,
try using pliers, especially Vise-Grips, to grasp the broken section
and twist it out. If this
doesn't work, take your tap and die set or electric drill and tap a smallhole
inside the broken piece. Then use your Phillips-head screwdriver
to grip inside the hole and twist out the broken piece.
Reverse Flow Problems
Reverse flow problem occurs with many pumps.
When the pump is pushing the water, the air may get trapped in the filter due
to either a leak in the system, or due to improper blending of the filter with
the new installation. While the running pump is pushing water against the trapped
bubble in the filter, the power to the pump motor is interrupted. The moment
the power goes off, the pump stops, releasing the bubble of air. This instant
release of air forces the column of water between the pump and filter to reverse
and flow backwards toward the pump, entering the discharge side of the filter.
This reverse flow of water into the discharge side of the pump starts the impeller
turning in the wrong direction. Within a few short seconds the pump impeller
can be turning at high speeds driving the motor in reverse as well.
When power is restored and the motor starts turning in the wrong
direction, the torque of the motor can be great enough to loosen and spin the
impeller from the shaft, stripping the threads.
Reverse flow is a very rare occurrence. As far as we can determine, it
can be overcome simply by using a check valve between the filter and pump.
is the most effective way to prevent it. Several large pump manufacturers have
recognized the same occurrence. To prevent reverse flow from occuring, they
have been securing the impeller to the motor shaft. This, of course, prevents
stripping its threads.
Model And Makes
pumps are variations of two basic concepts. Motors to drive these pumps
are made by several manufacturers. Century,
Franklin, A.O. Smith, General Electric, and others make all the various
styles and horsepower of
motors needed to run modern and older pump equipment. Some of the styles you
will need to specify when replacing are as follows. Remember,
the nameplate on the motor gives you this information, but it is always beneficial
to be familiar with these types.
While looking at the face of the motor, the end with the shaft will have a
definite pattern in the casting that looks like the letter C. The shaft is
This means one of two things. It has male threads on the end of the shaft
to receive the female threads of the impeller. Or, it is keyed, meaning the
shaft has no threads,
but rather a channel that runs the length of the shaft to accept the setscrews.
Look at the end of the motor that has the shaft. This style of motor includes
a flared bracket, square of course, that accepts the seal plate of the Sta-Rite
pump and the corresponding motor. These are only made with threaded shafts
because they work only with the type of pump that uses a threaded impeller.
This is a motor used on indoor spa booster pumps and fits that particular
style. Jacuzzi makes a number of these style of pumps and they all have
This is known as the housing at each end of the motor.
It is made of aluminum or cast iron. The iron
End Bell will rust
while the aluminum
won't. The aluminum more efficiently disperses heat away from the motor, thereby
prolonging its life. Some manufacturers give you a choice within each type
Full-Rated Or Up-Rated
The full-rated motor operates to its listed capacity, either 1 hp, 2 hp, etc.
The up-rated motor has a similar horsepower rating but can function to even
higher standards, if needed. This might
useful if the pool or spa gets full of leaves. For example, by
checking the service factors, you might be able to get a 1/2-hp up-rated motor
that is able to perform as well as a 1-hp full-rated motor.
As the name implies, this motor includes a switch box to wire it for two-speed
operation. For example, spas often use a two-speed motor. The lower speed
for circulating and heating, and the high speed for jet action. Wiring instructions
should be printed on the motor.
The energy efficient
motor is designed to save electricity over a comparable motor
of standard design.
Protective covers are made to fit over motors and are designed to keep direct
sunlight and rain off the motor housing.
The greatest danger to a motor is flooding of the equipment area in heavy rain
or when opening a filter. This will short out the windings
and void any warranty.
Submersible Pumps And Motors
There are essentially two types of submersible pump and motor combinations
that you will encounter.
High-Volume Pump-Out Units
Sometimes you need to drain a pool or spa. Several manufacturers make submersible
pump and motor units with long, waterproof electrical cords.
The suction side is at the bottom of the pump.
The return line is sized to be attached to your vacuum hose. Smaller units
to a garden hose to feed water out of the pump.
Low Volume Pumps and Motors
Fountains and small ponds use a smaller version of submersible pump and motor
unit that contain all of the same components as the larger ones.
Both high- and low-volume types contain the same components as the pumps and
motors and are repaired in much the same ways. Submersibles do
have more crucial and tricky seals and gaskets. However, because leaks in these
mean electricity in the body of water that can be fatal to both the motor and
you, any repair of the pumps should be done by certified electrician !!!
Booster Pumps And Motors For Spas
Pump and motor units that provide only jet action for spas generally are not
equipped with a strainer pot and basket. Otherwise, they are the same as other
units that are used for pools. Some units are designed to perform two
functions, and therefore, run at two speeds. When it runs at high speed (3450
rpm), it is to provide jet action. When it runs at a low speed (1750 rpm),
it is to circulate, filter, and heat the water and would have a strainer pot
To operate efficiently, spa jets require 15 gpm running through each one.
Therefore, if you have a system that delivers 60 gpm, you can install up to
four jets. Also, each jet requires 1/4-hp from its pump and motor, thus four-jet
spa would need at least a 1-hp unit. Keep in mind, this assumes the pump is
doing no other work. If it is pushing water through the filter and heater before
getting back to the jets, or if
is more than 20 feet from the spa, then some power will be lost and you will
need to calculate more than 1/4-hp per jet.