2 year old whisperflo pump with problem.

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M

mdhwoods

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Apr 18, 2009
143
Sarasota Florida
My 2 year old 1.5hp 2speed pump has a strange problem. It will start on low but not on high. If I try to start it on high it just hums then pops the thermal protection. Starts fine on low and runs on high just fine as long as it is already running. Suspected start capacitor, swapped it out to no avail. Any thing else I can look at before I spring for a new motor? Is there a start switch in the rear? Stinks that my 2 year old motor might be bad.

Thanks in advance

Mike
 
Can you post a picture of the motor and the motor label? Which capacitor did you replace, was it from the top of the motor, or from the back under the cover? Does the motor have one or two capacitors?
 
Since the pump runs after it's started, I don't think that it's windings or voltage, although it could be. The voltage supplied should be checked.

The start switch or start capacitor seem most likely. If there is no switch, I'm thinking that the "Run" capacitor might have been changed, and that the start capacitor is still bad. The "Run" capacitor is the top bump. The start capacitor (if it has one) would be in the back.

WhisperFlo_web.jpg


It could also be something binding the impeller. If you have a Permanent Split Capacitor design, it only has approximately 40% of the starting torque of a capacitor start design. You should try to turn the impeller to see if it easily turns and to see if it is clogged.
You could always take the motor to a local electric motor repair shop for evaluation. There is usually a small charge, but, for a 2 year old motor, it's probably worthwhile.

http://www.aosmithmotors.com/AOSECatalo ... cator.aspx
 
Thanks for all the input. It is 220 and looks just like that picture. I changed to capacitor under the bump as I thought that was the start. Voltage is fine as it runs on high as long as it is already running on low. Just won't start from high. I'll pull the motor apart this weekend and see if there is any drag in the impeller. I would think is there was it would have a much harder time starting in low. For now I have it coming on earlier so that the solar panels don't put it on high befor pump comes on. I should have more time to pull it apart this weekend. I was also thinking start switch but can't fine definite info that my motor has one.
 
The motor might be a Permanent Split Capacitor (PSC) high-speed and an energy efficient Capacitor Start/Capacitor Run (CSCR) low speed. The Permanent Split Capacitor (PSC) type has less starting torque than a capacitor start type motor.

Most likely, the low speed has a start capacitor and the high speed does not. The low speed would have about 2.5 times more starting torque than the high speed.

This would correspond to what you are seeing if something is impeding the rotation of the shaft/impeller.

Perhaps bad bearings, or debris in the impeller. You should be able to access the shaft from the back by removing the small shaft cover. Try rotating the shaft to see if it turns easily.

If you can post all of the motor label information, we should be able to look up more information about it.
 

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Here is a picture of the back of two motors. The one on the left is a Permanent Split Capacitor (PSC) design and the one on the right is a capacitor start induction run design.
centurion-ao-smith-motors.jpg

http://www.swimming-pool-information.co ... otors.html

On the left, you can see the shaft being accessed and rotated. On the right, the shaft is under the centrifugal switch. The centrifugal switch puts the start capacitor in-line for starting and it disconnects the capacitor once the shaft is rotating.
 
I suspect it is the one on the left as there looks to be a bump on the back and my wiring terminals also look like that if memory serves me right. Caught a cold so probably won't look to much into it tonight though I took a picture of the label. From what I can tell pentair only give a 1year warantee.

pump.jpg
 
As far as I can tell, the high speed is a PSC (Permanent Split Capacitor) switchless design, and the low speed is a capacitor start design that uses a Solid-State Microswitch instead of a centrifugal switch. I think that the low speed uses the same capacitor, but I'm not sure.

Overall, I think that some sort of restriction to the impeller or shaft is most likely.

Are you sure that the pump is only two years old? The date code looks like the motor was manufactured in November of 2005. That would be closer to six years ago. Although, the motor could have sat on the shelf for a while before being used in the pump build, and then the pump could have sat on a shelf somewhere for a while before being sold.
 
Ill pull the back cover off this weekend and see how easy it spins. I can tell you i bought it 2 years ago November. Maybe ill have a case with them if it turns out to be a bad motor. I bought it off amazon.com. It was sold by amazon and not a 3rd party.
 
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