Pentair 2HP Superflow - Too Hot to restart after shutting off to backwash etc.

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dish13

Member
May 17, 2022
13
Arkansas
New to this forum here, I apologize if this question has been asked before. I have a Pentair 2HP superflow SF-N1-2A that has been giving me some fits.

After the pump/motor has been running for a bit (either backwashing or filtering), and i choose to switch it off in order to change to either backwash or filter, there is just a buzzing sound and it will eventually stop buzzing and never come on. The motor at this point is extremely hot. I then have to turn off the power at the breaker switch, wait for the motor to cool down (sometimes up to an hour), and then it will switch back on after the unit buzzes for a half second or so (i assume the capacitor is what's buzzing).

I have replaced the capacitor just last week thinking this was the issue but it seems to have the same problem. Also, the motor does not sound "loud" when running but there is a slight periodic "hum" every half second or so as the pump is running. Once the pump turns on, everything seems to be functioning properly.

I have a small slight drip leak near the chlorinator and at the exit from the top of the filter. I have ordered a gasket seal o-ring kit, and new motor bearings - but don't want to disassemble the pump/motor unless that is something i need to do.
 
Welcome to TFP.

Post pics of your pump, labels on the front of your pump, and the motor data plate.

Is that the original motor or had it been replaced?

Some motors are thermostaticlly protected and will shut themselves down when they overheat. The buzzing you hear may be the thermostatic switch.
 
I’m not at home right now, this is what I have on my phone for pics of my pump and setup. The pump is original - this will be the 9th season for the pool (new in 2014).
 

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Yup, your motor is thermally protected.

I would check the voltage into the pump at the pump connections with a multimeter and confirm you have 240V between L1 and L2.; If you lost a leg and only had 120V the motor would run hot.

Post a pic of the CB that controls the motor.

Motor Thermally Protected.jpeg
 
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dish13 said:
I’m not at home right now, this is what I have on my phone for pics of my pump and setup. The pump is original - this will be the 9th season for the pool (new in 2014).
Click to expand...
Thermal switch might make a click when they break and again when they make connection. They are very much like a turn-signal flasher in your car.
If the motor "buzzes" long enough you might hear a slight click and the buzzing stop.
Century motors have always had an issue with the rear bearing cup in the end bell. There can be enough slop that, after expanding because of heat, the armature can move enough to become magnetically stuck to the stator.
You're at the short end of the average life of single-speed pumps, unfortunately.
 
ajw22 said:
Yup, your motor is thermally protected.

I would check the voltage into the pump at the pump connections with a multimeter and confirm you have 240V between L1 and L2.; If you lost a leg and only had 120V the motor would run hot.

Post a pic of the CB that controls the motor.

View attachment 411771
Click to expand...
I have 244 volts at the motor.

This morning the pump will not come on, only buzzing for a bit and then stops buzzing. It waits for a few mins then starts buzzing again.....is my motor shot or do i have any other options here??
 
1poolman1 said:
Thermal switch might make a click when they break and again when they make connection. They are very much like a turn-signal flasher in your car.
If the motor "buzzes" long enough you might hear a slight click and the buzzing stop.
Century motors have always had an issue with the rear bearing cup in the end bell. There can be enough slop that, after expanding because of heat, the armature can move enough to become magnetically stuck to the stator.
You're at the short end of the average life of single-speed pumps, unfortunately.
Click to expand...
Yes, i can hear a slight click. This morning the pump will not come on, only buzzes for a few seconds then stops buzzing. Waits a few mins, buzzing again then off. I have 244 V at the motor.
 
Also, i can turn the shaft by hand easily when the pump is switched to off. Once i switch to "on", while it's buzzing, the shaft turns about a quarter turn and stops, and i can move it with pliers slightly but it never spins. The shaft is immediately hot.
 

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dish13 said:
I had previously purchased bearings, a puller, and a new o-ring seal kit, i'm going to replace the bearings and seals and see what happens. At this point i don't think i have anything to lose.
Click to expand...
If you can spin the motor freely it is probably not the bearings. If you do a bearing replacement, don't reassemble the pump. Just hook the motor to the wiring and try to turn it on. It won't hurt and that is what is done at a motor shop to test. If it runs you can try reassembling the pump and see what happens. Be prepared that the motor may run alone but not under load.
 
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1poolman1 said:
If you can spin the motor freely it is probably not the bearings. If you do a bearing replacement, don't reassemble the pump. Just hook the motor to the wiring and try to turn it on. It won't hurt and that is what is done at a motor shop to test. If it runs you can try reassembling the pump and see what happens. Be prepared that the motor may run alone but not under load.
Click to expand...
Continued drama / questions. So i started with the process of replacing the bearings and separated the motor from the pump. At that time i discovered that there was a rock AND the lock bolt/screw in the impeller. Thinking that surely this was my problem, i reassembled everything and temporarily hooked up my power. Pump ran with no issues (sounded the same as previous), i shut it off after a couple mins and backwashed. Shut it off and re-started it to run for about a minute or so. Shut it off and turned off breaker so that i could put the wires properly back through the conduit elbow....now it is just buzzing again.

Is it just getting too hot somehow? What is causing the shaft not to turn after it gets "warmed up"??
 
dish13 said:
Continued drama / questions. So i started with the process of replacing the bearings and separated the motor from the pump. At that time i discovered that there was a rock AND the lock bolt/screw in the impeller. Thinking that surely this was my problem, i reassembled everything and temporarily hooked up my power. Pump ran with no issues (sounded the same as previous), i shut it off after a couple mins and backwashed. Shut it off and re-started it to run for about a minute or so. Shut it off and turned off breaker so that i could put the wires properly back through the conduit elbow....now it is just buzzing again.

Is it just getting too hot somehow? What is causing the shaft not to turn after it gets "warmed up"??
Click to expand...
Its new motor time.
 
It's me again! I took the old motor completely apart and noticed that something had damaged one of the "fins" of the motor, and i guess caused the whole shaft to bend. The rotor has been rubbing on the stator. I ended up just replacing my motor with the same model - only black from inyopools. First shipment the motor was damaged on the outside and i sent it back. Second one appeared OK, so i proceeded with doing the motor swap and re-seal job. When i got to the step of removing the impeller from the old motor, i noticed that the lock screw/bolt for the impeller had actually snapped off. The old motor would run (with the broken lock screw apparently) if i "babied" it to get it to start, and would continue to run about 8 hours a day while i waited for my new motor to arrive.

My question is this - is this lock screw even necessary for the impeller? You must screw on the impeller onto the shaft, and then the diffuser is screwed on top of that. I don't see much use for the lock screw - especially since it has came off twice now. Any harm in putting my new motor on the pump without the lock screw for the impeller?
 
dish13 said:
It's me again! I took the old motor completely apart and noticed that something had damaged one of the "fins" of the motor, and i guess caused the whole shaft to bend. The rotor has been rubbing on the stator. I ended up just replacing my motor with the same model - only black from inyopools. First shipment the motor was damaged on the outside and i sent it back. Second one appeared OK, so i proceeded with doing the motor swap and re-seal job. When i got to the step of removing the impeller from the old motor, i noticed that the lock screw/bolt for the impeller had actually snapped off. The old motor would run (with the broken lock screw apparently) if i "babied" it to get it to start, and would continue to run about 8 hours a day while i waited for my new motor to arrive.

My question is this - is this lock screw even necessary for the impeller? You must screw on the impeller onto the shaft, and then the diffuser is screwed on top of that. I don't see much use for the lock screw - especially since it has came off twice now. Any harm in putting my new motor on the pump without the lock screw for the impeller?
Click to expand...
That screw is a left-hand thread screw (lefty-tighty, righty-loosey). Without it in place water will be pumped directly into the motor front bearings, bypassing the seal. Yes, it is necessary (and expensive). Given the right conditions, when a pump turns off, especially a single-speed, (but I've seen it with a variable) the pressure in the filter will force water back through the pump and can unscrew the impeller from the shaft. If it moves far enough, the next time the motor starts, if one is lucky, it will thread back on. But most of the time it either strips the impeller threads, destroys the diffuser, or both.
 
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Have never seen one of those screws break unless it was by someone trying to remove it by turning the wrong direction. Many years ago (decades really) I broke one on the first pump I encountered that had one. It was on a older StaRite, but they used brass screws then. I unscrewed the impeller, not knowing it was there and broke it off. All new ones are stainless and I have no idea how it could break under normal use. Have seen many eaten away by bad water chemistry, particularly when a tab feeder was in the system.
Something else is going on, but you can't run the pump without it or the motor will be damaged.
 

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