1. Home
  2. How To Guides
  3. How To Select the Right Capacitor For Your Pool Pump Motor

How To Select the Right Capacitor For Your Pool Pump Motor

WRITTEN BY: 

  4.29 out of 5 stars on 24 ratings
(Click on a star to add your rating)

This guide discusses the two kinds of capacitors that could be used on pool pump motors: start capacitors and run capacitors. It also addresses how to know a capacitor is failing and how to replace it.

Click Here to View All Motor Parts (Capacitors, Bearings, Switches & More) 



Comments

Email

Print

Steps

Things You'll Need

Start Capacitors

Run Capacitors

Step by Step

Top

Step 1

CAPACITOR TYPES -  A pool pump can have two types of capacitors: a Start capacitor and A Run Capacitor. The Start capacitor is switched into the the motor's winding circuits on start up to help the motor turn over and come up to speed. When the motor is close to running speed, the Start capaciotor is switched out of the winding circuits. The Run capacitor is incorporated in the motor circuit to help increase running efficiency. It remains in the circuit as long as the pump motor is running. The start capacitor will generatlly be rated at 50-400 MFD and 125 or 250 VAC. The run capacitor will generally be rated at 15-50 MFD and 370 VAC. The capacitor in the picture is a Start Capacitor rated at 124-149 MFD 125 VAC.

Step 2

MOTORS WITH CAPACITORS - Not all pool pump motors use capacitors.  There are four common types of residential pool pump motors: Split Phase, Capacitor Start, Permanent Split Capacitor and Capacitor Start/ Capacitor Run.
The Split Phase motor is used extensively in spa and jetted tubs, and above ground pools. This design has a start winding and a start switch, but no capacitors.

The Capacitor Start motor is used commonly is in ground pool pumps.The starting torque is higher (150-175% of full load) and starting current lower than the split phase equivalent. The operation is similar to a split phase in that there is a start switch to take the start winding and capacitor out of the circuit once the motor reaches 2/3 to 3/4 of full speed.

The Permanent Split Capacitor motor does not have a start switch and is often referred to as a “switchless” motor. It does use a Run Capacitor that remains in the circuit at all times. The PSC design has significantly less starting torque than the capacitor start design.
The Capacitor Start/ Capacitor Run motor design is used to increase efficiency in run mode. Both Start and Run Capacitors are used. In run mode, PSC and Cap. Start/Cap. Run motors are the same.

Step 3

START CAPACITOR LOCATION - START capacitors are usually hard or glassy looking plastic enclosed can that are typically, though not always, found under the non-drive end canopy of the motor.

Click Here to Find Your Start Capacitor 



Step 4

RUN CAPACITOR LOCATION - RUN capacitors are usually the METAL (aluminum or steel) enclosed can capacitors that are most of the time, but not always, found under the "hump" on top of the motor - also referred to as the capacitor housing or "doghouse". This picture shows the location of the run capacitor under a doghouse.

Click Here to Find Your Run Capacitor

Step 5

START CAPACITOR FAILURE - Usually the effect of a failed START capacitor is a "sluggish startup" or "humming with no startup. When a START capacitor is starting to go bad, you might see some leakage of electrolytic oil,  and when it fails the vent opens and expells the electrolytic oils. A failed start capacitor will have a physical hole in the vent after it has failed.

Step 6

RUN CAPACITOR FAILURE - The effect of a failed RUN capacitor is usually "hi amps" and sometimes "humming with no start" and often times motor won't run in the hi amp condition without tripping thermal protector.  When a RUN capacitor is starting or has gone bad, the end of the capacitor that has the terminals and sometimes the opposite end without terminals bows outward. 
The capacitance reading would be significantly lower than rated if its failed.  There isn't a "vent" typically on RUN capacitors -- they expand/bow outward with a fail safe internal structure so that the bowing out of the terminals breaks the contacts internally in the capacitor in a fail safe mode.

Step 7

REPLACING START CAPACITOR - See our guide on "How To Replace a Pool Pump Capacitor". When you replace a capacitor, never put in a lower rated capacitor. If you can't find your size capacitor, it is acceptable to use the one rated one step higher. If you pump motor is continually burning up capacitors, try using the next one up in size. Capacitors are susceptible topower variations or increases. If you can't control your system power, you may need a capacitor with a little higher rating. Use this link to purchase the Start Capacitor you need.

Step 8

REPLACING RUN CAPACITOR - To replace a Run Capacitor, remove the Capacitor Cover (bump)  by removing the two screws. Then follow the precautions above to disconnect and replace the capacitor. As stated above, when you replace a capacitor, never put in a lower rated capacitor. If you can't find your size capacitor, it is acceptable to use the one rated one step higher. If you pump motor is continually burning up capacitors, try using the next one up in size. Capacitors are susceptible topower variations or increases. If you can't control your system power, you may need a capacitor with a little higher rating. Use this link to purchase the Run Capacitor you need

Click Here to View All Motor Parts (Capacitors, Bearings, Switches & More)

Comments

Top
Add a Comment
(1 to 40 of 450)

 Posted: 8/27/2022 

I have a dual flip 2 speed pump model 72727 and can’t figure out what capacitor my pool needs. I don’t even see a capacitor
 Reply

InyoPools Product Specialist  Posted: 8/30/2022 

Not all pool pump motors are designed with a replaceable capacitor. It is common for above ground pool motors not to have a replaceable capacitor.
 Reply

 Posted: 7/18/2022 

I have a USMotors pump that will not start in high. It will start in low and can be switched to high (in as little as 1 second) and will run fine. It only hums if turn to high from the off position. If will not restart in high after a power outage. The model number is R55cxfcm-0305. What do you recommend checking?
 Reply

InyoPools Product Specialist  Posted: 7/22/2022 

Unfortunately, I do not have a schematic for that motor, but you can check the barrel for the capacitor ratings. Guides to troubleshooting your issue: Pump Runs On Low Speed But Not On High Speed; How To Test A Pool Pump Motor Capacitor
 Reply

 Posted: 6/30/2022 

I have a Hayward super pump. Will a bad capacitor cause the breaker to trip? Everytime I try to turn on the filter pump my breaker trips.
 Reply

InyoPools Product Specialist  Posted: 6/30/2022 

A tripped breaker can be caused by a capacitor but also a bunch of other things. You can start by checking the capacitor, but if it checks out, you will need to test the circuit for continuity or a faulty breaker.
 Reply

 Posted: 6/22/2022 

I have a Sta-Rite pool pump model P6RA6F-206L 1.5HP. What start capacitor and run capacitor do I need to buy for replacement?
 Reply

InyoPools Product Specialist  Posted: 6/27/2022 

What is your motor's label's part, model, or catalog number? A picture of the motor label would be most helpful. P6RA6F-206L is the pump housing model number and does not identify the specific motor.
 Reply

 Posted: 6/27/2022 

The motor model number is #196250
 Reply

InyoPools Product Specialist  Posted: 6/29/2022 

The 196250 pool pump motor uses the RUN CAPACITOR, 30 MFD (5VR0303) (2444)
 Reply

 Posted: 6/19/2022 

Hi, great info on your site. I have a Hayward super pump that has blown the run capacitor leaving capacitor number illegible. The motor is Hanning - elektro werke. From motor plate: Type E7 D2 BS2 -7 - 238. Wired 240v. Can you tell from that what capacitor I need?
 Reply

InyoPools Product Specialist  Posted: 6/27/2022 

What is your motor's label's part, model, or catalog number? A picture of the motor label would be most helpful. Examples of the number we need can be found here: How to Read a Hayward Pool Motor Label
 Reply

 Posted: 6/10/2022 

My Pentair pump for the jets of an in-ground spa routinely blows the circuit breaker after running about half an hour. Is that a run capacitor issue, or something else? Every pool company visiting seems to have no idea. Thx!
 Reply

InyoPools Product Specialist  Posted: 6/10/2022 

Short answer: it could be. There is no way for me to tell you that from afar. You need to troubleshoot the motor/circuit or have an electrician do so if you do not feel comfortable with it. For more information: How To Test A Pool Pump Motor Capacitor or Using the Proper Test Equipment to Troubleshoot Pool Motors
 Reply

 Posted: 5/31/2022 

I think my capacitor went bad in my 1.5 horsepower hayward pump it makes a humming noise and nothing happens both sides of the capacitor aren’t bolting out as I read that that’s a way to tell if it’s bad anyway the capacitor says it’s a 108-130uf 165vac I can’t find one with the same numbers what can I use instead if there is something I can use I’ve only had the pump for 2 years wired at 240v
 Reply

InyoPools Product Specialist  Posted: 6/2/2022 

The correct replacement start capacitor is the 108-130 MFD (BC-108); it's used on motors wired for 115V and 230V.
 Reply

Anonymous  Posted: 4/16/2022 

Champ 115 I need a capacitor which one
 Reply

InyoPools Product Specialist  Posted: 4/18/2022 

The CHAMP115 is the pump housing. What is the part, catalog, or model number of the motor?
 Reply

 Posted: 4/14/2022 

What capacitor do I need for a 2.5 HP Emerson pump, Model: K63MWFGC-5027 which is in my Sundance Optima hot tub? Also, what is the best replacement pump model? Thanks
 Reply

InyoPools Product Specialist  Posted: 4/18/2022 

That appears to be a small-batch motor made specifically forSundance optima. Unfortunately, I could not find any motor part information on it. Your best shot at finding a capacitor is to find the part number on the capacitor. To find the correct replacement pump or a suitable motor replacement, I'd need to know the model number of the pump housing. K63MWFGC-5027 is specific to the motor.
 Reply

 Posted: 4/6/2022 

I have a start capacitor failure - hayward sp2670007x10 can you tell me which capacitor to buy?
 Reply

InyoPools Product Specialist  Posted: 4/6/2022 

That is the model number of the pump housing. We need to know the model number of the specific motor to find the correct capacitor. The motor model number is found on the tag that lists the motor specs like Amps, Volts, Service Factor. Or you can look at the capacitor to find its ratings.
 Reply

 Posted: 2/10/2022 

Hello I need to know which capacitor need to buy, it literally melted and I can see any number. Motor MOD S48AA11A79 1hp
 Reply

InyoPools Product Specialist  Posted: 2/14/2022 

The S48AA11A79 cross-references to a BN25 pool & spa pump motor; it does not have a replaceable capacitor.
 Reply

 Posted: 12/30/2021 

I have a US Motors model K63CXDFN-5152 and believe the start capacitor has failed after just over a year. Can you help with the replacement part number for the start capacitor?
 Reply

InyoPools Product Specialist  Posted: 1/3/2022 

The recommended capacitor for your K63CXDFN-5152 motor is the 161-193 MFD - BC-161 - Start Capacitor
 Reply

 Posted: 12/19/2021 

I have a 1 HP in ground pool pump and need to find a 200-240 uf 250 vac start capacitor. Can’t find a replacement with those numbers. What’s a good replacement?
 Reply

InyoPools Product Specialist  Posted: 1/3/2022 

What is the part number of the capacitor? If that is unavailable, what is the motor's part, catalog, or model number?
 Reply

 Posted: 10/26/2021 

Hi, I'm need to find the correct replacement dual pool pump capacitor and the current model shows the following: 30+10.0 uf +-6% 30CAC/B 50/60Hz
 Reply

InyoPools Product Specialist  Posted: 10/27/2021 

What is the part, model, or catalog number on the motor label?
 Reply

Anonymous  Posted: 10/27/2021 

Appreciate the help, I haven't had to buy a capacitor before so hopefully this is the info you're looking for. This is a Century Pool & Spa Motor: Cat B2977 Serial 24715J2 Type CXCP Part 7-K56AB45A01-05 Total HP = 1.95 Thank you!!
 Reply

InyoPools Product Specialist  Posted: 10/27/2021 

The parts schematic for the B2977 dual speed motor lists the 25 MFD - 628318-307 (2443). But if you want the same type of capacitor you have now, it would be the 30 MFD (5VR0303) (2444). I am not sure if the previous owner changed the capacitor in a previous repair or not.
 Reply

Anonymous  Posted: 10/15/2021 

Hi, I have an XP@ pump with an emerson 3HP motor model 06130453-2 also has 1563 +1795 on the casing. I need a run capacitor but the numbers are smudged off any help would be greatly appreciated thank you.
 Reply

InyoPools Product Specialist  Posted: 10/15/2021 

That model number (06130453-2) is not bringing up much information. That is the number on the motor label or on the capacitor? What is the model number of the pump housing?
 Reply

 Posted: 9/30/2021 

: I have a swimming pool pump with a Magnatek Century 230/115 VAC, Amps: SF 7.9/15.8, 1HP, 3450RPM , part 7-187524-20 with the capacitor missing, may I have a copy of the diagram to know which capacitor is needed?
 Reply

InyoPools Product Specialist  Posted: 10/1/2021 

Can you verify that 7-187524-20 is the part number written on your label? That number doesn't come up anywhere in our database.
 Reply

 Posted: 10/1/2021 

It reads on the label: CAT B376, PART 7 -187524 -20 HP 1.0
 Reply

InyoPools Product Specialist  Posted: 10/1/2021 

Is this motor on a pool or spa pump?
 Reply

Anonymous  Posted: 10/1/2021 

pool filter Pump motor
 Reply

InyoPools Product Specialist  Posted: 10/1/2021 

What is the model number of the pump it is on? Because we only carry schematics for pool & spa 1081 type motors; they are the standard for the industry. Neither of that motor's model numbers cross-references to anything. And when I do a regular google search, nothing pool and spa pop ups.
 Reply