Why do my pump capacitors keep failing?

Written By Timothy Te

11th January 2021

We’ve recently had a surge (pun intended) of customers asking for replacement capacitors for their pool pumps. We figured that we’ll put up a post outlining the ins and outs of your pool capacitor so you can have a better idea of what they are, why they’re failing, and how to determine if it’s just a capacitor problem or if it’s time for you to get a new pump (or motor).

What does a pool pump capacitor do?

Think of your pool pump capacitor as your pool pump’s battery. It functions the same as a car battery, giving your pump’s motor the required energy to reach the critical velocity (or RPM) before switching over to another power source. And much like car batteries, a busted capacitor won’t allow your pool pump to start. So if your pool pump turns on but won’t “start” then we recommend testing your capacitor before rushing out to buy a new motor or pump to see if it can still be patched up.

Four ways to determine if your pool pump capacitor has failed

Just like we mentioned earlier, you actually don’t need any special tools to check if your pool pump’s capacitor has failed. Listen, smell, think, and look!

  • Listen - If your pump isn’t “starting”, listen to it. If you hear a faint buzzing sound or a quiet hum coming from your pool pump then that’s a 100% sure sign that your capacitor has failed.
  • Smell - Give your pump a close smell. If you smell a burnt electrical smell then you have a busted capacitor.
  • Think - A pool pump capacitor generally has a lifetime rating of around 5,000 starts. While 5,000 sounds like a large number, it can go by very fast. So think about when you got your pump, give it a rough estimate. If you only use your pump once a day, 5,000 start is approximately 10-13 years. If you run your pump twice daily, then maybe 5-6 years. If you have a sand filter, take backwashing into account since a backwash cycle involves multiple start-stop cycles for your pool pump.
  • Look - This is an invasive way of checking your pool pump capacitor since you need to open up your pump to check. But if your pump isn’t humming, there isn’t a burnt electrical smell, and your pump is fairly new then this is the last resort. Once you open it up, look for any deformity in your pool pump capacitor. If your capacitor (or any battery for that matter) is starting to expand like a balloon, then it’s time to replace it.

Checking your pump capacitor for life

If your pump’s capacitor doesn’t smell burnt and looks absolutely normal, then you can use a multimeter to check if it still works. You can check out how to access your pool pump’s capacitor here in our guide on how to change your pool pump’s mechanical seals. Before attempting to remove or test your capacitor, be sure to discharge it by touching the terminals/leads with the metal head of a screwdriver. Don’t worry if it sparks, that’s actually a good sign, that means that your capacitor still holds a charge. Once your capacitor is off, take your multimeter and set it at the lowest ohm setting and touch the leads to the prongs of the capacitor. If the meter doesn’t move or stays at zero, then you have a bad capacitor on your hands.

Why do replacement capacitors fail?

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First off, make sure that the microfarad (uF) rating on your replacement capacitor matches the original exactly. Capacitors usually come in 20, 25, or 30 uF ratings so check, double check, and triple check that you’re ordering the exact rating. The second rating to keep an eye out for is the voltage. If you can’t find a capacitor with the exact same voltage rating, it’s OK to go up (i.e. if you have a 380V capacitor, you can use a 400V or higher capacitor) BUT NEVER choose a capacitor with a LOWER voltage rating.

Another reason why capacitors fail is when your pump runs hot. What does that mean? If your filters are dirty and your pump exerts more effort which in turn spikes the voltage level of your capacitor. Voltage also can spike up when your pool pump surges when you have a suction-side leak where air gets into your pump and causes your impeller to spin above the rated levels. To help preserve your pump capacitor life, check out our troubleshooting guide on how to eliminate pool pump surge here.

And finally, age. Age gets the best of us. If you’ve done everything correctly and your replacement capacitors still keep failing then it might be from other motor problems like the windings going bad or the bearings failing. Once you reach this point, a full motor replacement would be the way to go.

Conclusion

Capacitors are usually the first to go in any pool pump and they’re a quick fix. Simply pop them out and replace them and you should be good to go. The hard part is opening up the pump and getting to the actual part. Mr Pool Man has the most commonly used capacitors for pool pumps available online at excellent prices! No more searching through hundreds of rating combinations, just pick the right microfarad rating and it should be a straight swap with your existing capacitor.

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Now if it’s a motor problem, then Mr Pool Man recommends that you get a new pool pump altogether because one your pump motor has failed, it won’t be long till other components of your pump start failing as well. A new pool pump will give you years of worry-free operation especially with Mr Pool Man’s iron-clad warranties! Why not go all in and get an energy efficient variable speed pump? Pumps like the Water TechniX Pump Switch Variable speed pump will allow you to run your pump longer without running up your electricity bills so you'll avoid running your pump at multiple schedules during the day and extending the life of your capacitors. With an energy efficient pump, you can let it run for extended periods of time without worrying about massive electricity bills. No more complicated scheduling trying to get the best electricity rates!

Do you have any questions about this topic or the featured products? No worries, we're here to help! Drop us a question down below and we'll get back to you ASAP.

Happy swimming :)

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Written By

Timothy Te

Pool Guru at Mr Pool Man

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