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Pool Pump Motor Capacitor

Posted By: roberd

Pool Pump Motor Capacitor - 05/19/21 06:43 PM

Pool cleaner pump motor won't kick on so I assume I need to replace the capacitor. The original capacitor has the numbers of 25 uF +/-6, 370 volts and 50/60 Hz. I have a replacement capacitor for my main pool pump that has the exact same numbers however its farad numbers are 30uF +/-6. Physically the new capacitor will fit into the housing. Is the new capacitor close enough in farad to use in this application?
Posted By: topwater13

Re: Pool Pump Motor Capacitor - 05/19/21 06:46 PM

I have replaced them where the numbers didn't match exactly without issue. Mainly because the local supply only had one offering.
Posted By: roberd

Re: Pool Pump Motor Capacitor - 05/19/21 06:48 PM

That's what I was thinking as well, especially given the fact that they have the +/- range of 6 but it never hurts to ask.
Posted By: Texan Til I Die

Re: Pool Pump Motor Capacitor - 05/19/21 07:09 PM

It just means the replacement capacitor has a little more storage capacity. As long as the output voltage is right, it should be fine.
Posted By: Bullfrog

Re: Pool Pump Motor Capacitor - 05/19/21 07:26 PM

Yep, you can always go up. Try to not ever have to go down on uf’s. And keep the voltage the same.

Also, verify you have power to the motor first, to verify it’s not a breaker issue. Then kill it. 240 hurts
Posted By: Bullfrog

Re: Pool Pump Motor Capacitor - 05/19/21 07:29 PM

I have to ask why a pool cleaner pump is needed when you have a main pump/filter set up?
Posted By: Lazyjack

Re: Pool Pump Motor Capacitor - 05/19/21 07:32 PM

Close enough to try it. If it starts and runs. Motor is probably good. Order correct cap.

MFD rating should the same for max efficiency and motor life. VAC rating must be same or above. Most new run caps are rated for 370 or 440.
Posted By: Bullfrog

Re: Pool Pump Motor Capacitor - 05/19/21 07:39 PM

Motor life is a good point. Changing it does affect things in the long run.

I’ve always been told never replace a motor without a new capacitor.
Posted By: Lazyjack

Re: Pool Pump Motor Capacitor - 05/19/21 07:43 PM

Originally Posted by roberd
That's what I was thinking as well, especially given the fact that they have the +/- range of 6 but it never hurts to ask.


Picking fly specs out of pepper, the +/- is the variance of the cap specs.

25 mfd +/- 6 means that cap might be measure between 19 mfd and 31 mfd with a capacitance meter.
Posted By: Lazyjack

Re: Pool Pump Motor Capacitor - 05/19/21 08:00 PM

Originally Posted by Bullfrog
Motor life is a good point. Changing it does affect things in the long run.

I’ve always been told never replace a motor without a new capacitor.


Yup. In the grand scheme, moving up from a 25 mfd to a 30 probably will not make a difference. But you know I play it safe.
Posted By: roberd

Re: Pool Pump Motor Capacitor - 05/19/21 08:59 PM

Good question. We lucked out and the pool was already installed when we purchased the house. This is our first pool but it seems that the setup works well having the dedicated pump just for the cleaner.
Posted By: Texan Til I Die

Re: Pool Pump Motor Capacitor - 05/20/21 02:34 PM

I just remembered something that I haven't thought about in years. 40 something years ago when I was in college, we had an electronics lab that had all kinds of random components sitting around. We would find a capacitor about the size of a salt shaker, charge it up and play catch with it. It usually didn't take more than 5 or 6 tosses until someone would catch it wrong and get popped. Good times!
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