Whisperflo motor replacement and impeller compatibility

[CaptainB157]

Pump motor just died for my Whisperflo pump. Second to die in past 11 years. Had a Marathon 1.5HP, that accommodated the internal reverse threaded screw on the shaft of the motor. When to my pool store and was told that Century Pro 1.65 HP/SF 1.0 would be a suitable replacement. When I went to install the new motor, the shaft has external threading to seat the impeller, but does not have an internal reverse threaded hole to accommodate the Impeller’s screw that is part of Whisperfloo design. I have read that these screws are not necessary to seat the impeller, as most current motors have the external threading on the shaft.

Two concerns: Will my original impeller accommodate the slight increase in HP, or do I need to accommodate by using an impeller rated for 2.0 HP?

second, but not being able to place the screw through the impeller and into the motor shaft, there is now a through-hole that is not sealed. Can’t imagine that is good. Are there other impellers that don’t have a through hole that I should use instead?

 

[mas985]

Welcome to the forum!

You can always put a larger motor on a smaller impeller but not the other way around. But it sounds like the new motor is a 1.65 THP and not a 2 THP so I am not sure what you are asking.

They should have given you a 56Y square frame motor. Not every impeller needs the screw but as far as I know, every Whisperflo impeller has the screw hole. You could probably get away without having the screw but I would see if they have a motor with a screw hole.

Don't forget to change the shaft seal too or you may be replacing the motor again shortly.

 

[JamesW]

Without the screw, water will leak out. You might be able to plug the hole with epoxy. Just don't get epoxy in the impeller threads.

What impeller do you have?

What pump model number do you have?

 

[mas985]

How would water leak out? The seal is on the other side of the impeller.

 

[JamesW]

The hole in the impeller goes directly to the shaft. The impeller screw comes with an oring to seal the hole when the screw is installed.

 

[mas985]

Yes but that does not mean it would leak water all the way outside of the pump.

First, the seal on the other side of the impeller has a shaft grommet that fits tightly around the motor shaft so water should not travel any further than that assuming water could even get to the shaft.

In addition, the screw hole is on the suction side of the pump so if anything, air might travel out of the hole when the pump is running. But even when off, most IG pool pumps are above water level so there is a slight suction on that side of the pump. It might leak air but again, I think the shaft seal should prevent that.

 

[JamesW]

For the WhisperFlo, the seal cup that goes into the seal plate has a hole that allows the shaft to go through without contacting the seal at all. The ceramic part that goes in the impeller also does not touch the shaft.

There is no shaft grommet.

Water going through the screw hole will go onto the shaft and travel through the shaft threads and through the center of the seal without touching the seal.

The screw is at the center of the eye of the impeller, so low pressure that might suck in air, which isn't good.

When the pump is off, water can leak out.

 

[mas985]

When the pump is off, water can leak out.

Only if the screw is below the pool water level. In most IG installations, the pump is well above water level.

Also, I think the impeller brass fitting that the shaft screws into would seal the inside of the fitting so it wouldn't leak.

 

[CaptainB157]

Without the screw, water will leak out. You might be able to plug the hole with epoxy. Just don't get epoxy in the impeller threads.

What impeller do you have?

What pump model number do you have?

Wish I knew. The whisper flow pump label has long worn off and I am the second owner of the house. Same for the impeller size. Has I assume (dangerous, I know) that the impeller was the original, which was for a 1.5 horsepower original motor. The motor that I have (not yet fully) installed is a Century Pro HSQ 165

 

[CaptainB157]

Wow. I really appreciate all your help with this. Seems to me like the easiest ( and when I say easiest, I cringe at the thought that the pool store is gonna try to ding me with a 20 percent restocking fee) is to return the motor and insist on a model that accommodates the reverse threaded screw on the shaft, no? Which leads me to question, if the reverse thread screw is “old technology” That is no longer needed now that most motors have external threading on the shaft, do you all find that there aren’t many morons still available that will accommodate the Whisperfloo screw? OR, do you think it is worthwhile to search for an impeller that doesn’t have the through-hole that the WhisperFlo one does, and will accommodate being thread to the external threads on the Century Pro shaft?

 

[JamesW]

The shaft is threaded either way. The center screw doesn't really hold the impeller on. It's more of an extra precaution so that the impeller won't unscrew if the impeller gets spun backwards by water pressure from the filter when the pump is turned off.

Some pumps use a center set screw and some don't.

The brass female threads screw on to the stainless steel shaft threads but they won't make an airtight or watertight seal. Maybe if you used teflon or thread sealant, the threaded connection would be watertight.

If you told them that the motor was for your WhisperFlo pump, they should have known that it needed the center screw hole. They should replace it for free because it's their mistake.