Whisperflow pump problem

[mshumack]

I have a 2HP two-speed Pentair Whisperflow pump (model WFDS-8 #011523) that is acting up. It doesn't start all the time - and it seems to be getting worse. The pump is about two years old. It is contolled by a Pentair IntelliTouch (so it starts automatically - which is why I may not have noticed this problem for a while - although pump has been working/running when I check on pool in the afternoon).

When the pump is powered on, I hear a hum and and thump (or click) then nothing (pump doesn't run). After about a 30 seconds to a minute it will try again (and again hum-thump/click). This seems to continue until it starts or I shut off the power. It acts like it is getting overloaded and tripping an internal safety, then resetting (cooling?) and trying again to restart.

I noticed it this weekend but it could have been going like this for a while.

I turned off the power and put my hand down in the strainer opening and I could turn the impeller with my finger tips. It seemed like it started up on first time after doing this (Now I'm thinking there is a flat/bad spot on the motor winding), but it could just be coincidental.
I also saw a little squirt of water out of the space between the wet-end and the motor flange when it started.

I wondering if I should buy a seal kit and (something else?) and try to fix this myself, or just disassemble and take to a shop. Any idea what could be wrong?
Is there a "soft-start" on this motor that could be going bad?

Thanks

[dhanger]

I can't tell you anything about the electrical issues, but I have a Whisper-flo single speed that was doing the 'squirt' thing, the mounting bolts between the motor and pump had worked loose, I just tightened them and that took care of it. That was months ago, and still working fine.

Dan

[mshumack]

This morning it started up on its own (automation). When I came home it wasn't running. I turned off the power and manually turned the impeller again - when I powered it on it started right up. I bet there is a capacitor (starting aid/device - like on my well pump) that is going bad. Does anyone know more about this? I could not find any parts to service the motor - just the motor itself and parts for the wet end (seals, gaskest, etc.) after an internet search.

lastly, I can separate the motor from the pump and just take that in for repair - but if it is better to take the entire pump to shop, then I wil lhave to cut the PVC piping (inlet and outlet) which will be a hastle when it comes time to reinstall. How is this normally done? Does repair shop need entire pump to test/troubleshoot?

I don't mind taking it to the shop, but I hate not having any filtering on my pool for a couple of days (perhaps a week).

Thanks for reading/replying.

[Poconos]

Before you go pulling it apart check this thread:

http://www.poolforum.com/pf2/showthread.php?t=4800

There really are no dead spots in motors like this so I'm thinking it is the starter switch contacts. The starting capacitors usually fail open or shorted and don't usually fix themselves, but I guess it is possible, but unlikely, for it to go intermittent. I'd start with the contacts. It is something that is easy to try. Would be nice if you could pull the cover to expose the contacts and start cycling power to see if you can get it to not start, then tap the contacts.
Hope it is something simple.
Al

[mas985]

From what I understand, the Whisperflo uses a permanent split capacitor motor which means it doesn't have contacts nor a start capacitor.

However, if the bearings are going bad, it could explain the periodic stalls. One way to check is the next time it doesn't start tap the motor with a two by four and see if it starts.

[Poconos]

Very interesting Mark. Thanks, I learned something. The thing still has a capacitor but is not called 'starting' since it is always in the circuit. From what I read about this configuration is you don't have the high starting torque or high starting current of the switched configuration. Guess that doesn't matter with a pool pump though. I'm wondering if it comes up to speed relatively slowly and thus the pressure spike typically seen on startup is gone? Less stress on the system then.
Al

[mas985]

You are right about the starting torque being low at start. In a centrifugal pump, the required torque is proportional to the square of the RPM of the impeller (HP is proportional to the cube of RPM). So at start it is zero and climbs as the motor spins up so it is a perfectly fine design for a pool pump. So a PSC motor pump will start just as quickly as any other motor, at least what you can notice.

Also, most high efficiency motors are either PSC or CSCR (capacitor start, capacitor run). Both keep a capacitor in the starter winding to minimize the EMF losses and improve efficiency. The CSCR motor has more starting torque which really isn't needed. However, the run capacitor can be tuned in the CSCR for better run efficiency where the PSC motor requires a capacitor for both start and run situations. So the efficiency of the CSCR can theoretically be a little bit better than the PSC although from the CEC published test data, they are not all that much different. Personally, I think the PSC is better design since it eliminates one of the primary failures in a pool pump, the centrifugal switch so it should have better reliability.