How A Pool Pump Works

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This page provides a short tutorial on the main parts of a pool pump and how a pool pump works. This example describes a Hayward Super II Pump but the pool pump's parts and it's operation are common to most pool pumps.

Things You'll Need

Video

Step by Step

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Step 1

This picture shows the main parts of the pool pump in a pump cut-away. These parts include: the strainer basket cover that provides access to the strainer box to add water and clean out debris; the strainer basket that filters the larger pieces of the debris; the diffuser that direct water to and collects water from the impeller; the impeller that generates water pressure through centrifuge; and the motor that drives the impeller. Also shown are the two ports where water enters into the pool pump from the pool and exits out or the pump to return to the pool.

Step 2

This picture shows the basic flow of water through the pool pump. Water is sucked in through the basket, through the center of the diffuser (yellow) and through the center of the impeller. As the impeller spins, the water is thrown out the outer slots of the impeller where it is collected by the diffuser. The water is then funneled though slots in the diffuser into the high pressure water chamber and then out the exit port to the pool. Two notes: this picture shows a cut-away of the pool pump so that you can see the internal parts of the pump. In a working pump the diffuser would completely enclose the impeller. Also the only moving part in this pool pump is the impeller driven by the motor shaft. It's centrifugal motion is what sucks the water in and pushes the water out under pressure.

Step 3

This picture shows the inner operation of the diffuser with the diffuser partially pulled off. The diffuser funnels water from the strainer pot into the center of the impeller, then collects spun water from the outside edges of the impeller and releases the water through its own slots into the pressured chamber (dark blue arrows).

Click here to view the Hayward Super 2 pump parts. 

Step 4

This picture shows the operation of the impeller. Water enters the center of the impeller. As the impeller is spun by the motor, a series of blades, like a fan, push the water to the outside edges of the impeller where it exits through slots to be collected by the diffuser. It is this centrifugal force that generates the high pressure of the water exiting the pool pump.

Step 5

The pool pump has two chambers: chamber 1, the strainer pot, in the pull side of the pool pump before the impeller; chamber 2 is the push side of the pump after the impeller. There are four seals that keep the water flowing correctly between the chambers.

Step 6

This cut away of the pool pump shows the 4 seals that are part of most pool pumps: the strainer pot gasket, the diffuser gasket, the housing gasket, and the motor shaft seal. Their deterioration is the source of many of the common pool pump problems that plague pool owners.

Step 7

The strainer gasket usually sets in a groove on top of the strainer pot and provides a seal for the strainer pot cover. A poor strainer gasket will allow air to be sucked into the pump and prevent priming. The instructions for replacing a pump lid O-ring are included in the following guide: How To Clean Out the Pump Strainer.

Step 8

The diffuser gasket provides a seal between the strainer pot and the chamber around the diffuser and impeller. This chamber collects the pressurized water that is released through the output port. Without this seal the pressurized water will blow back into the strainer pot and the pool pump will loose pressure. For instructions in how to replace a diffuser gasket go to How To Replace Pool Pump Gaskets.

Step 9

The housing gasket provides the seal between the motor assembly and the pool pump assembly. If this seal is bad, the water will spray out of the pool pump and you will loose pressure and water. For instructions in how to replace a housing gasket go to How To Replace Pool Pump Gaskets.

Step 10

The motor shaft seal prevents water from leaking out of the pressure chamber along the motor shaft into the motor assembly. When this happens you will see water dripping from the bottom of the motor. For instructions in how to replace a motor shaft seal go to How To Replace A Motor Shaft Seal.

Step 11

If you are repairing your pump or pump motor consider purchasing a GO-KIT. Each GO-KIT contains the replacement seals and gaskets you will need to repair your pump. A typical GO-KIT like the one pictured here for a Hayward pump, contains the motor shaft seal (2 parts), the pump housing gasket, the pool pump lid o-ring and the diffuser gasket. Note: These GO-KIT are generally unique to the make and model of the pump. Order the GO-KIT specified for your pump's make and model.

Click here to view GOKITS. 

Comments

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(41 to 80 of 121)

InyoPools Product Specialist  Posted: 2/24/2013 

Pat - Intermittent pump operation can be caused by the wrong or unstable voltage to your pump's motor. If the motor is set up to run on 220V and it is wired for 115V, it will become over heated and temporarily shut down to cool. This will damage the motor over a short period. Use a volt meter to check the voltage into your pump's motor. Also check that the voltage to the motor is stable and does not decrease more than 15% up and down. If it is unstable, contact your power company.
 Reply

 Posted: 2/22/2013 

My pump will shut off for 30 to 45 seconds and then come back on and run fine for 30 minutes or so then shut off again. Its been doing this since it was new. It does'nt seen to hurt anything, what may cause this.
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InyoPools Product Specialist  Posted: 11/25/2012 

Jim - I would pull the motor off of the pump and check that the impeller is still sound. If the impeller is good, check for leaks on the suction side of the pump. See our guide on locating leaks. Otherwise, like you say, you've done well to have this motor for 14 years. It may be time to replace it with a more efficient one.
 Reply

 Posted: 11/25/2012 

My pump motor is operating, but it is not pumping the water. It doesn't make any unusual noise. What is the most likely cause. Could it be that the impeller is has broken loose from the motor shaft? Is it likely that I need a whole new pump. The motor pump assembly is fourteen years old.
 Reply

InyoPools Product Specialist  Posted: 10/28/2012 

Richard - Check for obvious leaks around the filter or any joints you separated to change the sand. Check to see if water is going out your waste line. If it is, you may have a blown spider gasket in the multiport valve.
 Reply

 Posted: 10/28/2012 

after changing the sand in my filter whenever i have the pool on filter the pool is losing water as if the waste outlet may be open? please help
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InyoPools Product Specialist  Posted: 9/16/2012 

Dennis - Take the motor out of the pump and see if you can spin the shaft easily. If not , you may need a new motor. Also check that the impeller is not jammed. Then check your motor's capacitor. It may have failed.
 Reply

InyoPools Product Specialist  Posted: 9/16/2012 

Francis - If you have a cartridge filter, you can bleed the air out by opening up the relief valve at the top until only water comes out. However I doubt that is your problem after running two hours. Sounds like you have an air leak. Check anything that was changed during the pool cleaning like the strainer basket. Is the cover gasket on correctly?
 Reply

 Posted: 9/15/2012 

Pump motor is not running at all. I have power from the breaker box, the breakers have been checked,they're fine the timer is fine and the time clock is fine have power to the pump but motor is not running Bad pump?
 Reply

 Posted: 9/11/2012 

My weekly pool cleaners came this am, turned on the filter, cleaned the pool and then they shut the filter down. My pool filter starts at 10am, now two hours later the jets are spitting out air bubbles and water. The motor window has air in it. Question, how do I get the air out?
 Reply

InyoPools Product Specialist  Posted: 9/4/2012 

wet - You may have a bad capacitor. See our guide on checking and replacing a capacitor.
 Reply

 Posted: 9/2/2012 

All of the sudden my pool pump stops working, (its a Hayward , 3 years old) its emits a buzzing noise and the breaker (cut-off) jumps. It took it apart, a can turn the impeller using the shaft of a screwdriver, i feel some resistance.The impeller is clean of debris. is start the pump, its just buzzes and the breaker jumps again. My motor is shot?
 Reply

InyoPools Product Specialist  Posted: 8/30/2012 

concerned pool owner - I'm not sure what's going on here. You say you hear the water running but nothing's coming out of the returns to the spa or pool. Where is the water going? It has to be going somewhere if you still have good suction. Do you have a major leak and is your pool water level dropping?
 Reply

 Posted: 8/27/2012 

My pool pump was circulating water through the filter and out to the inlets in the pool and fountain in the hot tub. It was running for awhile and realized later that I could hear the motor but no water was cascading out of the hot tub or comming out the inlets. When I check the filter to the [ump it had no debree but the water was super hot. I shut everything off check the valves and tried it agai i could here the water rush again no fountain no inlets when I turned on the sweaper line the sweaper took off however still no fountain nor inlets any suggestions would be appreciated..
 Reply

InyoPools Product Specialist  Posted: 8/13/2012 

pchickey1 – According to the manufacturer, the strainer pot assembly screws into the center of the housing assembly. If it isn’t holding, the threads in either the housing assembly or the strainer assembly may be stripped and either or both pieces may have to be replaced.
 Reply

Anonymous  Posted: 8/13/2012 

I can't get the strainer pot assembly to stay connected to pool pump. It keeps coming off. O-rings appear to be OK.
 Reply

InyoPools Product Specialist  Posted: 7/7/2012 

danny, I would check the impeller to see if it is clogged. If it is ok, you may have slow leak on the suction side of the pump or a partial blockage in one of your lines.
 Reply

InyoPools Product Specialist  Posted: 7/7/2012 

jr32016 - I would pull the motor out of the pump housing and check that the impeller is not broken or worn to the point that is rubbing on the diffuser around it. If the impeller is good and not wobbling on the shaft, it is likely that your motor bearings are going and it may be time for a new motor.
 Reply

InyoPools Product Specialist  Posted: 7/7/2012 

cheappool - I would replace the pump/filter set with a Game SandPro 50 Pool Filter System, model number 4510. Many customers are using this set to upgrade their Intex pools. Game even provides adapters to fit existing Intex piping as well as others.
 Reply

 Posted: 7/6/2012 

my water flow is about half what it use to be. is it possable that my impellar is clogged

 Reply

 Posted: 7/5/2012 

Suddenly my pump start making a loud noise seems to be working fine but with this loud noise is there some lubrication needed? or need to replace something
 Reply

 Posted: 7/3/2012 

I have a cheaper pool....collapsable, blow up top ring and fill pool....(probably less than $300) with a cheaper pump that was included. My pump will work, motor runs, but a very slow flow. Any suggestions?
 Reply

InyoPools Product Specialist  Posted: 6/30/2012 

eddielou - It sounds like you should change your shaft seal as well as the housing gasket. If the shaft seal is bad and is leaking water into the motor, you should not run the motor until it is replaced
 Reply

 Posted: 6/30/2012 

I had some water spraying (it was kind of sputtering as if the water was being thrown out by the fan...paddles that force the water into the filter)???) out where the pump shaft goes into the housing of the pump. After running the pump and filter for about 10 minutes the water stopped spraying/sputtering but appears to be leaking out and dripping down from the same place (where the pump shaft goes into the housing of the pump)Pressure on filter remains good and pressure on return is still good. I'm guessing from what I am reading that the motor shaft seal may need to be replaced? Also, I'm thinking an o-ring/gasket may need to be replaced on the pipe that connects the pump to the filter. Last year there was a slow drip from this area as well. Will it hurt the pump to run it if I can't get it fixed right away?
 Reply

InyoPools Product Specialist  Posted: 6/29/2012 

jlaw - It sounds like you have an air leak in the suction side of your pump. See our response to ChuckChillout's comment.

 Reply

InyoPools Product Specialist  Posted: 6/29/2012 

ChuckChillout - You probably have a leak on the suction side of the pump - going into the pump. It doesn't take much. Check the o-ring on your strainer cover. If you have unions on the section side, make sure the threads are wrapped with several layers of plumbers tape and that the o-ring is set properly. Make sure the threads of the fitting going into the pumps in wrapped with plumbers tape. Check that your pool's water level is above the half way mark on your skimmer opening. It these efforts don't solve your problem, you may have to call a pool professional.
 Reply

 Posted: 6/27/2012 

My pool pump will not pump water. When i checked and cleaned all of the baskets and reprimed my pump. It pumped for a few seconds. The presure went up to about 10..then fell of to nothing and stopped pumping again? Any ideas?

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 Posted: 6/27/2012 

I have a Hayward Super Pump and am having trouble with suction. I called my local pool guy to open the pool so the pump was turned on and filter setting ran from 6/20 to 6/24. The morning of the 25th I go out to perform a backwash and I noticed the pump was getting no pressure. I checked the filter tray and nothing was clogged. I stuck my finger in the suction hole and nothing seemed to be blocking that either. As per suggestion on another blog site I filled the filter tray with water and turned the pump on to eliminate the possibility of it being an impellor issue (noticed the water level go down when pump turned on). Outside of a clog at the skimmer end, any other ideas of where the clog could possibly be located?
 Reply

InyoPools Product Specialist  Posted: 6/23/2012 

LosAltosWay - Almost sounds like you are using an above ground pool pump for an in ground pool. Above ground pool pump are not self priming. If this is not the case, check for leaks in the suction lines and check that your pump's impeller is not broken or clogged with debris.
 Reply

 Posted: 6/22/2012 

Hi, My pool stopped circulating. I am able to force water from the skimmer with a plumber's back-flush kit to the strainer and the pump takes it from there back to the pool and the spa. However, if I don't force the water with the plumber's kit, then no water (not even a weak flow) goes from the skimmer (or the main drain) back to the pump. What do you think may be the problem? Thank you in advance
 Reply

InyoPools Product Specialist  Posted: 6/22/2012 

barbodd - Check your wiring. It sounds like you have 115V coming in and your pump is setup for 220V. When that happens, the pump will overheat and shut off, then restart when it's cooled off.
 Reply

InyoPools Product Specialist  Posted: 6/22/2012 

Dave,
It appears like your pump is a Doughboy which runs the opposite was from most other pumps. In any case it should be designed so that the impeller tightens with the rotation of the motor. I would recommend you go to the Doughboy web site for further information.

 Reply

 Posted: 6/21/2012 

I need help - I opened my pool yesterday and the pump runs fine for about 10- 15 minutes then shuts off - when trying to reset electrical breaker it will not run neither is the pump - can this be a problem with the pump or electrical - please help
 Reply

 Posted: 6/20/2012 

Without going it to too much detail, with the new motor I have the impeller loosened and that is what lead me to believe the motor was turning the wrong way. After further investigation, the new motor spins CCW and the impeller tightens on the shaft CW. This seems like it would be correct, does that make sense to you?

My pump model is Pool Power Pak II and it is 20+ years old. The motor is on a switch since the electronics burnt several years ago and it was not worth repairing. If there is other information that would help you help me, please let me know. You can use email if you like, I added that to my comment information.

 Reply

InyoPools Product Specialist  Posted: 6/20/2012 

Jack - Yes, Doughboy is one of the few exceptions.
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Anonymous  Posted: 6/20/2012 

In regard to motor direction.

Jake - All pumps, with minor exception, run counter clockwise when you are looking at them from the pump end. CCWPE

Is Doughboy one of the exceptions?

 Reply

InyoPools Product Specialist  Posted: 6/16/2012 

Annette - If you water flow to the pump and out the returns is good, it sounds like your only problem with water flow is with you relief valve It may be clogged. As far as your pool not clearing up, we sell a product called Floc to clear suspended particles out of the water. Follow the instruction carefully.
 Reply

 Posted: 6/16/2012 

My pool will not clear up. 18,000 gal pool with DE filter.I don't know the name of the parts so bear with me. There is good flow going from the pool to the pump (you can see and feel the suction at the pool skimmer basket). If I open the pressure relief valve on the filter, water barely dribbles out , whereas before water would shoot out 6 feet. The flow of water going back into the pool is good. AlsoI think that some DE is winding up in the bottom of the pool. Pool chlorine/PH is good. Ive cleaned the filter and checked that there are no holes in the grids and observed no water leakage when i reassembled it. I felt around the impeller and I don't feel any debris. Suggestions?
 Reply

InyoPools Product Specialist  Posted: 6/6/2012 

Jake - All pumps, with minor exception, run counter clockwise when you are looking at them from the pump end. CCWPE
 Reply

 Posted: 6/5/2012 

How can you tell if the pump motor should run clockwise or counter clock wise. IMPELLER - SP2610 C
 Reply