How To Select the Right Capacitor For Your Pool Pump Motor

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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.

Things You'll Need

Step by Step

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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.

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.

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

Comments

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(1 to 40 of 164)

 Posted: 1/24/2019 

I was hoping I could find the start capacitor part number for a flo-master HP model #:03110766-1 Thank you,
 Reply

InyoPools Product Specialist  Posted: 1/24/2019 

Hello Carl - I was unable to cross reference your model number. What is the MFD/UF and voltage rating of the start capacitor? Those specifications should be on the capacitor.
 Reply

 Posted: 1/20/2019 

Can you locate the right Capacitor from the model and serial # on a Hayward pump ? Or do you have to remove the start capacitor and look for a part #
 Reply

InyoPools Product Specialist  Posted: 1/21/2019 

Hello Kevin - we can find it either way. We would need the model, part, or catalog number from the motor label. The pertinent information on the capacitor barrel is the microfarad (MFD) and the voltage ratings.
 Reply

 Posted: 1/18/2019 

Hi-I have a Century B2748, 2 HP pool motor. Part 7-196263-20, Type CX, FRY56Y, SF1.30, HZ60, RPM 345, Volts 230, AMPS SF11.5. Thanks to your excellent information I have determined the Run Capacitor is bad. What is the correct part number to order?
 Reply

InyoPools Product Specialist  Posted: 1/21/2019 

Hello Mike - a replacement capacitor for your B2748 motor is the BC-124.
 Reply

 Posted: 1/13/2019 

3450 HP 2. S.F.1.1 1.6kw 127/220 v. Inside115-230v 24.0/12.0. 60Hz
 Reply

InyoPools Product Specialist  Posted: 1/14/2019 

Hello Yahay, to find the right capacitor, it would help to have the part, model or catalog number from the motor label. Can you find that info on the same label you found the above information?
 Reply

 Posted: 1/14/2019 

3450 HP 2. SF1.1 1.6kw 127/220 v Inside115-230v 24.0 / 12.0. 60HZ C48M2EC11C3 code/ 001F11T
 Reply

InyoPools Product Specialist  Posted: 1/15/2019 

Unfortunately, we do not have a parts list for your C48M2EC11C3 (Q1152). What is the MFD/UF and voltage rating of your capacitor? This should be printed on the capacitor.
 Reply

 Posted: 1/15/2019 

capacitor This was working on the pump motor but not the original condenser 124-148 UF 110V - 60HZ
 Reply

InyoPools Product Specialist  Posted: 1/16/2019 

If the previous capacitor was working, I'd stick with the same one. The replacement start capacitor would be part number 5270-11.
 Reply

Anonymous  Posted: 12/17/2018 

Pool pump (WFE-4, looks like it crosses to a "Pentair", althoug nameplate sez "PACFAB Moorpark, CA...?)). Need a replacement run capacitor I think. (getting the hum, then click, then nothing; Intermittent, starts and runs more often than not, ~80-90% of time last couple months) Motor nameplate sez "Century Centurion AO Smith, but doesn't list model (Cat... ___ blank?) Ser: BW3-22, Part: 7-177450-03, Type: CX.
 Reply

InyoPools Product Specialist  Posted: 12/18/2018 

The WFE-4 is the model of pump housing. The housing number does provide an idea of the size of your motor but doesn't identify your specific motor or the correct capacitor that fits the motor. As we state in the article, there are a couple of ways to gets the correct info for the capacitor: look on the capacitor for parts numbers or ratings, or find the model number on the motor label.
 Reply

 Posted: 12/15/2018 

I need a motor starting capacitor. It is a E212600. Can you tell me how I can acquire one. Thank you.
 Reply

InyoPools Product Specialist  Posted: 12/18/2018 

Hello Alfredo - the part number E212600 does not cross-reference to any capacitor that I could find. Do you have the ratings from the capacitor case?
 Reply

Anonymous  Posted: 11/30/2018 

Does the Hayward power flo Matrix have a capacitor to the motor?
 Reply

InyoPools Product Specialist  Posted: 11/30/2018 

Thank you for contacting Inyo. What is the catalog or part number on the motor label?
 Reply

 Posted: 11/12/2018 

is there a capacitor for a Hayward SP3400VSP pool pump and where is it locate. I have a drive error - pump has failed to start and the pump will not start.
 Reply

InyoPools Product Specialist  Posted: 11/15/2018 

Hello Dave - Unfortunately, there is not a replaceable capacitor on the Hayward SP3400VSP. In most cases, the motor and drive need to be replaced.
 Reply

 Posted: 10/12/2018 

Hey Ken what rated capacitor do I need for a century centurion 1081 2hp motor for a heyward northstar pump?
 Reply

InyoPools Product Specialist  Posted: 10/16/2018 

Damon - 1081 is the type of motor; pretty much every pool and spa motor is labeled with a 1081. As we say in the article, you can look on the jacket of your current capacitor. Or find the part using the model, part, catalog, or model number from the motor's label.
 Reply

 Posted: 10/1/2018 

Hello Angelo - We'd be glad to assist you. What is the catalog or model number on the motor label?
 Reply

 Posted: 9/29/2018 

I have a Jandy FloPro 1,5hp single speed pump. Does this pump have a start capacitor as well as a run capacitor ? I replaced a defective capacitor which I think is the run capacitor but the pump still won't run. So wondering if there is supposed to be another capacitor ?
 Reply

 Posted: 9/20/2018 

Hello Ken - everything I have found on the Balboa Ultimax 1016026, says that it is a run capacitor only type.
 Reply

 Posted: 9/20/2018 

My pump is also doing the humming noise without starting. Upon inspection, I was only able to locate the run capacitor. After the end cover of the motor was taken off, it appears there is only the coil pack but no additional capacitor. Could you help confirming if the Balboa Part 1016026 Model PUUMC2252582FR indeed has just the one capacitor? Thank you!
 Reply

 Posted: 9/13/2018 

Hello Paul - Your motor only has one capacitor. The replacement run capacitor for your 0-193986-24, also known as model B2854, is part number 5270-08.
 Reply

 Posted: 9/13/2018 

Hi, My pump is humming so I would like to try the capacitor(s) before I replace the motor. The motor can spin by hand. Unfortunately, the East Coast weather is not cooperating with taking the electrical parts of the motor apart to identify the capacitor(s). Would you be able to tell me what capacitor or capacitors it uses so I can have them in hand for when the sun peaks out? Its a Century Centurion attached to a Jandy pump. Part number 0-193986-24. Your website cross-references it to a b2854. It doesn't have the HP on the Century label but a separate Jandy label says 1.50 x 1.10 = 1.65. The Century label says type=CX frame=Y56Y HP= SF= PH=1 HZ=60 RPM=3450 Volts=230/115 Amps= SF 8.0/16.0 Time=CONT Encl=DP Form=KJM Code=J InsulClass=B AMB=50c
 Reply

 Posted: 9/11/2018 

Hello Dan - We were able to identify the capacitors for your 7-187563-02, also known as a B2235 motor. It takes a total of three capacitors. The start capacitor is part number 610807-002. The run capacitors are 628318-309 and 628316-315. The run capacitors are in the same case on the motor.
 Reply

 Posted: 9/5/2018 

Hello Corin - The C48L2N134B1, also known as the UST1152, only uses a start capacitor. The correct replacement capacitor is the 5270-14.
 Reply

 Posted: 9/4/2018 

Hello lleff - The correct start capacitor for model C48K2N143B1 (UST1102) is part number 5270-14.
 Reply

 Posted: 9/3/2018 

Hi, I have this pump. Can you tell me what capacitor it requires? I've read it requires a split capacitor but I am not sure what that means and I want to ensure I put the right one on. A. O. Smith 4 HP, 12 AMP, 230 V, Dual Speed Part Number 7-187563-02, Type CXPM Frame R56Y Thanks Dan
 Reply

 Posted: 9/2/2018 

If the motor hums and after a while starts, does that require to replace the start capacitor or the running capacitor or both? What start and running capacitors are required for a C48L2N134B1 pump?
 Reply

 Posted: 8/31/2018 

Hi. What is the correct start capacitor for a Hayward Super Pump - Model c48k2n143B1? 1hp. 115/230 volts. 15 amps?
 Reply

 Posted: 8/28/2018 

Hello txnplano - The correct run capacitor for the Pentair LA01N booster pump motor is part number 5270-08.
 Reply

 Posted: 8/28/2018 

What is the correct capacitor for a Pentair LA01N booster pump?
 Reply

 Posted: 8/27/2018 

Hello Jason - It is acceptable to replace a capacitor with a higher voltage as long as the MFD rating is the same as the original.
 Reply

 Posted: 8/26/2018 

Hi, is it OK to swap in a 370 volt run capacitor for a 440? i think the 440 is too much, as this size runs hot and burns out, as i've had to replace every year or so. thanks for any advice.
 Reply

 Posted: 8/20/2018 

Hello Tom - the correct start capacitor replacement for the C48L2N133, ST1102 1 HP motor is the 610807-002
 Reply

 Posted: 8/20/2018 

Hello Anita - The important ratings needed when matching a start capacitor is the microfarad (UF or MFD) rating part number shown as 680171-002. Sometimes the 'U' in the UF is lowercase, backward with a squiggly tail. The correct replacement is our part number, 5270-14.
 Reply